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General Discussion => New Physics for Space Technology => Topic started by: KelvinZero on 07/18/2017 12:31 am
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This is a call for reputable, published scientific speculation on what consistant FTL could look like.
One of my frustrations with FTL proponents is that I have never seen serious attempts to explain what they even mean. What result they expect, how the paradoxes are all avoided. There just doesn't seem to be much interest in this. If I had produced some math that seems to imply FTL, it just seems natural to me that the first thing to try is to investigate what the maths says would happen if I attempt to produce one of the various famous paradoxes. That would explain what the maths actually means in the real world.
(I think the closest I have seen to reputable investigation suggests that things like warp drive can indeed avoid paradoxes.. you just can't ever exit them. Paradox averted :-) Has anyone done better? )
UPDATE (from a message further down):
While not published, an interesting paradox-free FTL while trying to preserve as much as possible of relativity is described here (preferred FTL frame):
http://www.physicsguy.com/ftl/html/FTL_part4.html#subsec:specialframe
https://en.wikipedia.org/wiki/Cosmic_microwave_background#CMBR_dipole_anisotropy
Can anyone think of a clear example that FTL with just one message, or failing that, wrt to just one special reference frame (eg the CMB rest frame), will still create a paradox?
UPDATE 2
I think I just had an interesting insight about the "CMB rest frame as special" solution to FTL paradoxes. It gives me more confidence that it really does avoid all paradoxes.
My insight was that "simultaneous" in this context can be defined as all points where the CMB is the same temperature. For example if we had 'Instantaneous' travel, this would mean we were sliding around an isosurface through space-time where the temperature of the CMB (in the CMB rest frame) is exactly 2.725°. If we were using our FTL 13 billion years ago, the universe would be orange and our instantaneous travel would take us to another point of the universe with the exact same shade of orange.
FTL that is less than instantaneous would deliver you to some point in space time where the temperature is a tiny bit lower.. never higher.
Relativistic flight also obeys this rule.
If our FTL obeys this simple rule, I think we can be confident that no combination of FTL and relativistic flight would ever deliver you back to your starting point before you left.
(This in no way argues that such an FTL feature is shoehorned into physics. The topic was simply about whether we could describe FTL without paradox that renders our description undefined.)
UPDATE 3
The thing I wanted to add was, the CMB rest frame choice isn't merely nice. I think it is special because I think it almost rules out any other choice.. if you are going to chose some frame and label it special it pretty much has to be this one.
Why? because you are either choosing the ONLY definition of "instantaneous" where you are travelling between points of the universe that have the same temperature and entropy, and look pretty similar, or you are choosing ANY OTHER one where travel in one specific arbitrary direction takes you to a younger, hotter universe, and the other direction takes you to a colder one, even though the universe does not look hotter or colder in either of those directions. Only one choice of reference frame is nice, all the others are "yuck". Apart from being "yuck", there are probably horrible exploits you could implement if you could slide freely between entire observable universes at different states of entropy. IMO that makes one choice head and shoulders above any other possible one.
UPDATE 4
https://backreaction.blogspot.it/2015/06/does-faster-than-light-travel-lead-to.html (https://backreaction.blogspot.it/2015/06/does-faster-than-light-travel-lead-to.html)
I think [Sabine Hossenfelder's] point could be summarised by saying that the way to solve such paradoxes is to acknowledge the fact that, for macroscopic objects, there exist a sort of "preferred frame" given by the unidirectionality of the arrow of time that is over-imposed on top of fundamentally time-symmetric interactions.
She also posted a link to an article by Nemiroff and Russell where they calculate explicitly when the closed loop starts going back in time.
https://arxiv.org/abs/1505.07489 (https://arxiv.org/abs/1505.07489)
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This topic has unsurprisingly come up here before.
The last discussion I saw on it ended up with this comment:
https://forum.nasaspaceflight.com/index.php?topic=41389.msg1597244#msg1597244
It isn't clear to me if there is a set of consistent rules for where wormholes can or can't exist that would always prevent time travel. The argument Nilof made of "just close the wormhole if a closed timelike curve forms" seems compelling, but I feel like this would create situations where you could get FTL information by methods such as checking whether or not you can open a wormhole in a specific situation.
I would like to see a formal investigation of what conditions you could have on wormholes to guarantee that they don't violate causality.
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There is no resolution as long as Einsteins relativity holds entirely. So we have to modify it.
What is the simplest such modification? Assume that there is an absolute frame of reference for FTL travel.
The most natural such assumption is CMB rest frame. FTL travel will always happen with respect to this frame. The rest of physics can work normally and is unaffected, but any FTL effect will have to happen relative to CMB frame. Your FTL speed will differ depending on which direction with respect to CMB you are going. This cures those temporal paradoxes.
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Im sure I have been on threads discussing this before, I was probably on that one too..
And I think one result was that you can produce a paradox with just a single FTL 'jump'.. If that is true then choosing a single reference frame does not resolve the issue. Maybe someone can confirm that.
The difference from earlier threads is that I wanted to concentrate on published solutions or speculations. Someone must have done this.
(just googled "resolutions to FTL paradoxes", found various "researchgate.net" papers, but I don't know if they are reputable.. I will probably have a go at reading them to at least see what they claim.. not sure I will understand them well enough to even do that.)
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If I had produced some math that seems to imply FTL, it just seems natural to me that the first thing to try is to investigate what the maths says would happen if I attempt to produce one of the various famous paradoxes. That would explain what the maths actually means in the real world.
Well, General Relativity's math already produces paradoxes: closed timelike curves inside Kerr black holes.
They even seem to be physically realizable. Very large (supermassive) rotating black holes exist, and there are no laws of physics preventing a spaceship entering them and flying along a CTC. In a large enough hole the ship built from real, existing matter, not unobtanium, can survive tidal forces.
The ship may never emerge back from black hole, yes, but still, how to explain that while orbiting on that CTC, the ship can return into its own past (previous orbit)???
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Im sure I have been on threads discussing this before, I was probably on that one too.. And I think one result was that you can produce a paradox with just a single FTL 'jump'.. If that is true then choosing a single reference frame does not resolve the issue. Maybe someone can confirm that.
The difference from earlier threads is that I wanted to concentrate on published solutions or speculations. Someone must have done this.
(just googled "resolutions to FTL paradoxes", found various "researchgate.net" papers, but I don't know if they are reputable.. I will probably have a go at reading them to at least see what they claim.. not sure I will understand them well enough to even do that.)
It was published in JBIS, Nov. 2015 issue, (didn't come out until Feb. 2016).
http://www.jbis.org.uk/paper.php?p=2015.68.347 (http://www.jbis.org.uk/paper.php?p=2015.68.347)
There are no paradoxes here. Another paper I put together earlier also resolved several issues with warp drives.
https://www.researchgate.net/publication/251231464_THE_CONTROLLED_REFRACTIVE_INDEX_WARP_DRIVE (https://www.researchgate.net/publication/251231464_THE_CONTROLLED_REFRACTIVE_INDEX_WARP_DRIVE)
Todd
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Well, General Relativity's math already produces paradoxes: closed timelike curves inside Kerr black holes.
I suppose that is true. I know that General relativity has known holes.
But FTL is meant to operate in the real world in the sense that a postman can leap in an FTL ship, fly to alpha centauri, drop of a letter and come back. If that produces a paradox then you haven't actually described what the postman just did. Relativity can have holes in it and still be a great, useful theory. If a proposal for FTL cannot describe FTL, it can't have much value.
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There are no paradoxes here. Another paper I put together earlier also resolved several issues with warp drives.
You can't just say "There are no paradoxes here".
You have to be able to explain how the known paradoxes are avoided. If you have avoided paradoxes, you have to describe how your definition of FTL is constrained from the general form, that most definitely produces paradoxes.
The explanation cannot require complicated math to describe. To prove, sure, but not describe.
A person trying to implement one of these paradoxes will not be diverted by a maths storm. They have to experience something. A force. An alternate history. Annihilation. Something.
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There are no paradoxes here. Another paper I put together earlier also resolved several issues with warp drives.
You can't just say "There are no paradoxes here".
You have to be able to explain how the known paradoxes are avoided. If you have avoided paradoxes, you have to describe how your definition of FTL is constrained from the general form, that most definitely produces paradoxes.
The explanation cannot require complicated math to describe. To prove, sure, but not describe.
A person trying to implement one of these paradoxes will not be diverted by a maths storm. They have to experience something. A force. An alternate history. Annihilation. Something.
Did you read them? There is no paradox because the coordinate speed of light is a variable in the theory. Objects never exceed the speed of light in their own local coordinates. Varying the speed of light changes the scale of rulers (ships) and clocks (atoms).
In "ST Voyager" we see the ship elongate into the distance, then snap away in a bright flash. In this theory, that animation is what it would look like.
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Objects never exceed the speed of light in their own local coordinates.
That is the whole idea of a closed timelike curve, a path that can be traveled moving at lightspeed (or slower) where the thing travelling the path ends up in its own past. It in no way prevents any paradoxes.
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Did you read them? There is no paradox because the coordinate speed of light is a variable in the theory.
Apparently I am having difficulty explaining why that answer is extremely unsatisfactory to me. I will try one more time.
I could not possibly understand a theory that proves something that is beyond generally accepted science. If it is correct, it is very very hard.
What I can understand is the general problem, for example how special relativity plus an instantaneous communicator trivially creates a time-travel paradox.
If your theory has any meaning in the real world, you must be able to explain how it changes the experience of someone attempting to produce one of these simple paradoxes.
If you cannot answer this, lets end this conversation here.
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While not published, an interesting paradox-free FTL while trying to preserve as much as possible of relativity is described here (preferred FTL frame):
http://www.physicsguy.com/ftl/html/FTL_part4.html#subsec:specialframe
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What bothers me is simply; When there is a certain segment of time that passes from the starting time at the origin point and the destination point, in a progression towards entropy, no matter how short the duration, even though a significant distance is traveled, everyone insists that it's a form of time travel.
This puzzles me. If a train from New York to Washington DC only takes a few hours to travel the distance, while walking on foot between the two would take several days or weeks, is the train a form of time traveling device?
By this notion, if a craft, traveling at the velocity of light would take eleven years to go from here to Ross 128, as an example, would using a technique that would allow a craft to make that same trip, in weeks, relative to both the starting point and the destination, STILL be a time machine?
If the same amount of time passes for the craft, the starting point and the destination, I don't see an issue. Optically, the people at the target location would not see the launch from the starting point for eleven years, minus the travel time, while the starting point wouldn't see the craft arrive for eleven years minus the travel time. People on the craft MAY experience a different time rate from the time observed by both the starting point and destination point, but will still have a forwards progression of time.
So long as action precedes causation, I don't see a paradox here.
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By this notion, if a craft, traveling at the velocity of light would take eleven years to go from here to Ross 128, as an example, would using a technique that would allow a craft to make that same trip, in weeks, relative to both the starting point and the destination, STILL be a time machine?
You are entirely ignoring relativity. There are reference frames where The ship will be moving backwards. This is not "apparent" backwards motion, but actual backwards motion after accounting for speed of light delays in sensing. This is what creates the paradox. To illustrate:
Someone in such a frame passing by Ross 128 when at (just estimating) 0.7 c towards Earth could receive a message from the first craft just as they arrive at Ross128, "we ran out of chocolate." The second craft then activates its own equivalent FTL drive. Since it started in a frame where the distance between Earth and Ross 128 is smaller, its trip will be shorter, and since the first ship will be travelling backwards in that frame, the second ship can arrive before the first ship left, and then give them extra chocolate so they don't run out.
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What bothers me is simply; When there is a certain segment of time that passes from the starting time at the origin point and the destination point, in a progression towards entropy, no matter how short the duration, even though a significant distance is traveled, everyone insists that it's a form of time travel.
This puzzles me. If a train from New York to Washington DC only takes a few hours to travel the distance, while walking on foot between the two would take several days or weeks, is the train a form of time traveling device?
By this notion, if a craft, traveling at the velocity of light would take eleven years to go from here to Ross 128, as an example, would using a technique that would allow a craft to make that same trip, in weeks, relative to both the starting point and the destination, STILL be a time machine?
If the same amount of time passes for the craft, the starting point and the destination, I don't see an issue. Optically, the people at the target location would not see the launch from the starting point for eleven years, minus the travel time, while the starting point wouldn't see the craft arrive for eleven years minus the travel time. People on the craft MAY experience a different time rate from the time observed by both the starting point and destination point, but will still have a forwards progression of time.
So long as action precedes causation, I don't see a paradox here.
Well it wouldn't look like time travel to any of those points of view. It would look like time travel to another observer in motion relative to those observers. This is because velocity not only causes length contraction it causes clocks at different points to be out of sync.
Imagine trying to put a 20 foot rocket inside a box only five feet thick. Does not fit right? But say we accelerate the rocket to a velocity such that it is only one foot long. Fly it into the box and simultaneously close the front and back of the box. For a tiny fraction of a second the rocket is fully inside the box and the front and back are closed. Then you must simultaneously open the front and back to let the rocket out.
But now lets imagine what that looks like from the point of view of someone riding on the nose of the rocket. From their point of view it is the box that is length contracted. How do they fit in a box less than a foot thick? From their perspective they don't. From their perspective the front and back of the box is never closed at the same time. They do not see themselves ever enclosed by the box. If you put a clock on the front of the box and the back of the box they will show the same time in one frame but will show different times in another frame.
Now imagine you have a teleporter that can instantaneously transport you from the front of the box to the back of the box and you do this at the exact time that the rocket is fully enclosed. The rocket is fully enclosed and the front and back are still closed when you arrive. no problem right?
But again look at it from the point of view of the person on the rocket. From this point of view the front and back are never closed at the same time. So if they see you teleport from the front when the door is closed to the back when the door is closed then you have teleported from one point in time to another point in time.
Different observers can see events that are simultaneous in one frame as happening in a different order in another. And in relativity this is not an illusion. There is no absolute frame and so there is no absolute order that the events took place in as long as the events are far enough apart in space and close enough in time that a light beam cannot connect the events. As long as you do not violate the speed of light there is no paradox.
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I'm not sure there really is a resolution to the problem short of "many worlds"
This would imply that any conceivable FTL travel is in essence interuniversal.
An interesting idea. Why bother colonizing your galaxy on trips well below light speed if your culture reaches a technological ability to farm and colonize other universes for whatever it needs going back to the earliest period possible/useful and regions using stable wormhole gateways. You won't be altering the future for whatever might have happened in that part of the universe. It simply will never have happened in that reality.
That's not to say this sort of universal past mining might not be without consequences. https://arxiv.org/pdf/1505.05952.pdf
Beyond me, though.
We really should take another look at the WMAP Cold Spot :)
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By this notion, if a craft, traveling at the velocity of light would take eleven years to go from here to Ross 128, as an example, would using a technique that would allow a craft to make that same trip, in weeks, relative to both the starting point and the destination, STILL be a time machine?
You are entirely ignoring relativity. There are reference frames where The ship will be moving backwards. This is not "apparent" backwards motion, but actual backwards motion after accounting for speed of light delays in sensing. This is what creates the paradox. To illustrate:
Someone in such a frame passing by Ross 128 when at (just estimating) 0.7 c towards Earth could receive a message from the first craft just as they arrive at Ross128, "we ran out of chocolate." The second craft then activates its own equivalent FTL drive. Since it started in a frame where the distance between Earth and Ross 128 is smaller, its trip will be shorter, and since the first ship will be travelling backwards in that frame, the second ship can arrive before the first ship left, and then give them extra chocolate so they don't run out.
Please provide a math example of how a ship can "physically" move backwards in time. Or a signal for that matter. These paradoxes arise for the same reason the Twin paradox arises. Ignoring which frame (clock/ruler) actually accelerated to the speed v, and which did not. Special Relativity is the special case where two "identical" inertial reference fames are passing each other at a relative speed, v. It says nothing about the history of how they got that way, or the physical effects of acceleration that "caused" one system's clock to run slower than the other, as in the Twin paradox.
In GR, the coordinate speed of light is a variable, it's not a constant. It's not absolute in any sense, as it is in SR. Two inertial reference frames at different gravitational potentials, with different conformal scaling, are not identical. Lorentz transformation do not apply.
In my model, which is a conformal scaling of the metric due to a relative refractive index, K. It simply changes the scale of local rulers and clocks, which are used to measure space and time in the region affected by the metric potentials. Changes affecting local rulers and clocks does not suddenly allow you to send messages backwards in time. It just changes the rate at which these effected clocks move forward in time. No paradoxes can occur in this case, and it still conforms with GR. It also conforms with SR, but ONLY in the "special case" where the two inertial frames have the same identical potential. SR is not generally true for every conceivable situation! That is why you get paradoxes.
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I'm not sure there really is a resolution to the problem short of "many worlds"
This would imply that any conceivable FTL travel is in essence interuniversal.
An interesting idea. Why bother colonizing your galaxy on trips well below light speed if your culture reaches a technological ability to farm and colonize other universes for whatever it needs going back to the earliest period possible/useful and regions using stable wormhole gateways. You won't be altering the future for whatever might have happened in that part of the universe. It simply will never have happened in that reality.
That's not to say this sort of universal past mining might not be without consequences. https://arxiv.org/pdf/1505.05952.pdf
Beyond me, though.
We really should take another look at the WMAP Cold Spot :)
The "Many Worlds" theory is one of the only ones that I have ever found that resolves the majority of time travel issues.
Essentially, if one were to go backwards in time, one would wind up leaving their original universe and shunt over to one NEARLY identical to one's origin universe, so any actions taken in THIS new universe, would have no effect on your home universe. (ie, the old "Killing one's grandfather before one's father was born" paradox)
Whether or not this would would resolve the "Time Travel vs. FTL" debate is problematic, as we, at present, have no way of testing this out. If, indeed, this FTL travel causes a shunt to another universe, then the FTL trip back would return one to a SECOND universe, virtually identical to the one, one started in.
Of course, this is also assuming that other versions of one's self are likewise shunting between universes. This would avoid all sorts of messy problems with mass variations between universes and the same matter occupying the same space/time, but in two different locations. (This also brings to mind the possibility of quantum interaction with one's self at a distance. Would one become entangles with one's self over a vast distance?)
If this is a case of universe shunting, then one would notice differences from one's home universe after a significant number of "FTL flights", but likely could write off minor differences as memory lapses.
Overall, I tend to think that distance and velocity are only relevant to time in relativistic flight. Moving Space itself, or shunting outside of normal Time/Space, or even some sort of wormhole drive, should not violate "time's arrow" unless the arrival at the destination happens before the departure from the origin point, relative to the reference frame of both the origin and the destination points.
Even some form of spacial fold shouldn't violate "time's arrow", as the actual transition would still take at least Planck Time to actually occur.
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By this notion, if a craft, traveling at the velocity of light would take eleven years to go from here to Ross 128, as an example, would using a technique that would allow a craft to make that same trip, in weeks, relative to both the starting point and the destination, STILL be a time machine?
You are entirely ignoring relativity. There are reference frames where The ship will be moving backwards. This is not "apparent" backwards motion, but actual backwards motion after accounting for speed of light delays in sensing. This is what creates the paradox. To illustrate:
Someone in such a frame passing by Ross 128 when at (just estimating) 0.7 c towards Earth could receive a message from the first craft just as they arrive at Ross128, "we ran out of chocolate." The second craft then activates its own equivalent FTL drive. Since it started in a frame where the distance between Earth and Ross 128 is smaller, its trip will be shorter, and since the first ship will be travelling backwards in that frame, the second ship can arrive before the first ship left, and then give them extra chocolate so they don't run out.
Please provide a math example of how a ship can "physically" move backwards in time.
A ship can't physically move backwards in time for the same reason it can't travel faster than the speed of light.
You ask for the math. The math is the Lorentz transformations. For any hypothetical object travelling FTL, it is trivial to find a reference frame where it travels the path backwards.
Or a signal for that matter. These paradoxes arise for the same reason the Twin paradox arises. Ignoring which frame (clock/ruler) actually accelerated to the speed v, and which did not. Special Relativity is the special case where two "identical" inertial reference fames are passing each other at a relative speed, v. It says nothing about the history of how they got that way, or the physical effects of acceleration that "caused" one system's clock to run slower than the other, as in the Twin paradox.
But they didn't accelerate in the above example except for engaging FTL, which should work the same in either frame. There are only 4 spacetime points that matter. When ship 1 entered and exited FTL and when ship 2 entered and exited FTL. Ship 1 enters FTL where ship 2 exits and vice versa (give or take the width of the ship to avoid a crash). Ship 1 exits FTL before ship 2 enters it, but ship 1 entered FTL after ship 2 exited it.
Only special relativity is needed to describe the above situation, and the explanation of independent of whatever magic generates the FTL.
None of your comments about general relativity apply. Special relativity is a special case of general relativity, so if it is a problem in special relativity, it still is in general relativity.
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By this notion, if a craft, traveling at the velocity of light would take eleven years to go from here to Ross 128, as an example, would using a technique that would allow a craft to make that same trip, in weeks, relative to both the starting point and the destination, STILL be a time machine?
You are entirely ignoring relativity. There are reference frames where The ship will be moving backwards. This is not "apparent" backwards motion, but actual backwards motion after accounting for speed of light delays in sensing. This is what creates the paradox. To illustrate:
Someone in such a frame passing by Ross 128 when at (just estimating) 0.7 c towards Earth could receive a message from the first craft just as they arrive at Ross128, "we ran out of chocolate." The second craft then activates its own equivalent FTL drive. Since it started in a frame where the distance between Earth and Ross 128 is smaller, its trip will be shorter, and since the first ship will be travelling backwards in that frame, the second ship can arrive before the first ship left, and then give them extra chocolate so they don't run out.
Please provide a math example of how a ship can "physically" move backwards in time.
A ship can't physically move backwards in time for the same reason it can't travel faster than the speed of light.
You ask for the math. The math is the Lorentz transformations. For any hypothetical object travelling FTL, it is trivial to find a reference frame where it travels the path backwards.
Or a signal for that matter. These paradoxes arise for the same reason the Twin paradox arises. Ignoring which frame (clock/ruler) actually accelerated to the speed v, and which did not. Special Relativity is the special case where two "identical" inertial reference fames are passing each other at a relative speed, v. It says nothing about the history of how they got that way, or the physical effects of acceleration that "caused" one system's clock to run slower than the other, as in the Twin paradox.
But they didn't accelerate in the above example except for engaging FTL, which should work the same in either frame. There are only 4 spacetime points that matter. When ship 1 entered and exited FTL and when ship 2 entered and exited FTL. Ship 1 enters FTL where ship 2 exits and vice versa (give or take the width of the ship to avoid a crash). Ship 1 exits FTL before ship 2 enters it, but ship 1 entered FTL after ship 2 exited it.
Only special relativity is needed to describe the above situation, and the explanation of independent of whatever magic generates the FTL.
None of your comments about general relativity apply. Special relativity is a special case of general relativity, so if it is a problem in special relativity, it still is in general relativity.
In my Warp Drive paper, the warp field effectively negates the effects of SR by changing the length of the ship and the clocks it contains, so that they match the original rest frame where it started from, at all times. In other words, there is no length contraction or time dilation of the accelerated starship. Therefore, the motion of the ship is not relativistic, it's Newtonian. Lorentz transformations do not apply.
Again, how can changing the rate of my clock, moving faster or slower, suddenly give me the ability to travel backwards in time, or send a message backwards in time? It doesn't, it can't. The paradox is only there because SR is not applicable, yet everyone insists it is.
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In my Warp Drive paper, the warp field effectively negates the effects of SR by changing the length of the ship and the clocks it contains, so that they match the original rest frame where it started from, at all times. In other words, there is no length contraction or time dilation of the accelerated starship. Therefore, the motion of the ship is not relativistic, it's Newtonian. Lorentz transformations do not apply.
Again, how can changing the rate of my clock, moving faster or slower, suddenly give me the ability to travel backwards in time, or send a message backwards in time? It doesn't, it can't. The paradox is only there because SR is not applicable, yet everyone insists it is.
None of what you said changes the scenario I described. When 2 people have a copy of your magic FTL device, what happens when they act out the scenario above?
Remember, GR allows CTCs, just all of the solutions can't be implemented for reasons like needing exotic matter with negative mass. You have not shown that you don't generate CTCs.
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In my Warp Drive paper, the warp field effectively negates the effects of SR by changing the length of the ship and the clocks it contains, so that they match the original rest frame where it started from, at all times. In other words, there is no length contraction or time dilation of the accelerated starship. Therefore, the motion of the ship is not relativistic, it's Newtonian. Lorentz transformations do not apply.
Again, how can changing the rate of my clock, moving faster or slower, suddenly give me the ability to travel backwards in time, or send a message backwards in time? It doesn't, it can't. The paradox is only there because SR is not applicable, yet everyone insists it is.
None of what you said changes the scenario I described. When 2 people have a copy of your magic FTL device, what happens when they act out the scenario above?
Remember, GR allows CTCs, just all of the solutions can't be implemented for reasons like needing exotic matter with negative mass. You have not shown that you don't generate CTCs.
The scenario you put forth has an assumption built into it. That is, in the frame of ship 2 the distance to Earth is shorter AND this makes a difference when the FTL drive is switched on. In my model, when the FTL is switched on, regardless of how fast ship 2 was going relative to the Earth prior to that. After the switch, the length of the ship and the clocks on board are "tuned" to be the same as that on Earth, at all times, regardless of the FTL speed. So the distance to Earth is not what it was before the FTL was turned on. In the case of ship 2, that distance gets longer in the FTL frame. Lorentz transformations go out the window. In other words, there is no FTL frame where the distance to Earth is shorter.
The gamma factor becomes dependent on the refractive index, K.
1/gamma = sqrt((1/K) - K*(v/c)^2) = 1 Where, K is a function of (v) that solves this equation. A ship surrounded by a field where K << 1, can travel at speeds v >> c, and still have dtau/dt = 1. But it still doesn't go backwards in time.
On another note:
Another way to avoid the paradox would be a BSG Jump drive. Regardless of how fast the ship is moving, it can instantaneously jump to another point in space and arrive "at rest" at those coordinates. There would be no way to send the ship back in time, because it didn't take any time to get there.
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The scenario you put forth has an assumption built into it. That is, in the frame of ship 2 the distance to Earth is shorter AND this makes a difference when the FTL drive is switched on. In my model, when the FTL is switched on, regardless of how fast ship 2 was going relative to the Earth prior to that. After the switch, the length of the ship and the clocks on board are "tuned" to be the same as that on Earth, at all times, regardless of the FTL speed. So the distance to Earth is not what it was before the FTL was turned on. In the case of ship 2, that distance gets longer in the FTL frame. Lorentz transformations go out the window. In other words, there is no FTL frame where the distance to Earth is shorter.
The Earth is 11 light years away in the Earth frame, and around 8 light years away in the ship frame when the ship 2 FTL is switched on. It is utterly nonsensical to say that the ship's reference frame instantly changes to have the same inertial motion as Earth when it turns on. There is nothing special about the Earth frame.
All you have done is created a preferred frame for the entire universe which conveniently is the Earth frame. This has no experimental basis in reality, and instead contradicts everything known about relativity and astrodynamics.
Another way to avoid the paradox would be a BSG Jump drive. Regardless of how fast the ship is moving, it can instantaneously jump to another point in space and arrive "at rest" at those coordinates. There would be no way to send the ship back in time, because it didn't take any time to get there.
You apparently have never read the first page of any description of relativity. The very first point is that there is no such things as an arbitrary "at rest." No reference frame is special. For an instantaneous jump drive, the ship would just have to accelerate back in the direction it came sufficiently quickly, before reengaging the drive. It accelerating into a different frame would mean that it is now in a frame where the time it departed from is in the future. If all they want is to send a message back in time, it is even easier, just have someone already moving fast at the destination.
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Im sure I have been on threads discussing this before, I was probably on that one too.. And I think one result was that you can produce a paradox with just a single FTL 'jump'.. If that is true then choosing a single reference frame does not resolve the issue. Maybe someone can confirm that.
The difference from earlier threads is that I wanted to concentrate on published solutions or speculations. Someone must have done this.
(just googled "resolutions to FTL paradoxes", found various "researchgate.net" papers, but I don't know if they are reputable.. I will probably have a go at reading them to at least see what they claim.. not sure I will understand them well enough to even do that.)
It was published in JBIS, Nov. 2015 issue, (didn't come out until Feb. 2016).
http://www.jbis.org.uk/paper.php?p=2015.68.347 (http://www.jbis.org.uk/paper.php?p=2015.68.347)
There are no paradoxes here. Another paper I put together earlier also resolved several issues with warp drives.
https://www.researchgate.net/publication/251231464_THE_CONTROLLED_REFRACTIVE_INDEX_WARP_DRIVE (https://www.researchgate.net/publication/251231464_THE_CONTROLLED_REFRACTIVE_INDEX_WARP_DRIVE)
Todd
That thing reads like the Entabulator video.
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Warptech, lightspeed should be called Causality Speed. That would clear many problems of understanding it.
Watch these two videos which explain with spacetime diagrams why FTL is time travel.
https://youtu.be/1YFrISfN7jo
https://youtu.be/HUMGc8hEkpc
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The scenario you put forth has an assumption built into it. That is, in the frame of ship 2 the distance to Earth is shorter AND this makes a difference when the FTL drive is switched on. In my model, when the FTL is switched on, regardless of how fast ship 2 was going relative to the Earth prior to that. After the switch, the length of the ship and the clocks on board are "tuned" to be the same as that on Earth, at all times, regardless of the FTL speed. So the distance to Earth is not what it was before the FTL was turned on. In the case of ship 2, that distance gets longer in the FTL frame. Lorentz transformations go out the window. In other words, there is no FTL frame where the distance to Earth is shorter.
The Earth is 11 light years away in the Earth frame, and around 8 light years away in the ship frame when the ship 2 FTL is switched on. It is utterly nonsensical to say that the ship's reference frame instantly changes to have the same inertial motion as Earth when it turns on. There is nothing special about the Earth frame.
All you have done is created a preferred frame for the entire universe which conveniently is the Earth frame. This has no experimental basis in reality, and instead contradicts everything known about relativity and astrodynamics.
Another way to avoid the paradox would be a BSG Jump drive. Regardless of how fast the ship is moving, it can instantaneously jump to another point in space and arrive "at rest" at those coordinates. There would be no way to send the ship back in time, because it didn't take any time to get there.
You apparently have never read the first page of any description of relativity. The very first point is that there is no such things as an arbitrary "at rest." No reference frame is special. For an instantaneous jump drive, the ship would just have to accelerate back in the direction it came sufficiently quickly, before reengaging the drive. It accelerating into a different frame would mean that it is now in a frame where the time it departed from is in the future. If all they want is to send a message back in time, it is even easier, just have someone already moving fast at the destination.
You have many preconceived notions and assumptions! Keep an open mind.
The Alcubierre warp drive had the feature that dtau=dt, the proper time aboard the ship matched the same time as the folks back home. That is the "Goal"! It is what my drive was designed to do. Earth is only preferred, because that is where we come from. It could just as easily be tuned to a different home-clock, but what clock you choose is irrelevant. Time is relative to where you call "home".
I never said "at rest" in a preferred frame. What I meant was "at rest with respect to the target coordinates", regardless of what speed the ship was moving relative to those coordinates when the BSG Jump Drive was activated.
Now, if you talk to Marc Millis or some other advocates, then the CMB represents a preferred "rest frame" of the Universe. How do you feel about that? I don't agree with it, but it is what it is. We can detect doppler shift and therefore, motion relative to the CMB.
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As you say the only frame that matters is the frame that the person with the FTL drive is in. Instead of randomly switching from the ship 2 frame to the Earth frame, let ship 2 stay in the ship2 frame and see what happens.
"at rest with respect to the target coordinates" is nonsensical. The "target coordinates" would be an event in space-time. An event does not have a velocity, and can be described in any arbitrary frame with any velocity.
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As you say the only frame that matters is the frame that the person with the FTL drive is in. Instead of randomly switching from the ship 2 frame to the Earth frame, let ship 2 stay in the ship2 frame and see what happens.
"at rest with respect to the target coordinates" is nonsensical. The "target coordinates" would be an event in space-time. An event does not have a velocity, and can be described in any arbitrary frame with any velocity.
You are far too nit-picky! You just like to argue and be right.
If I'm the pilot of ship 2 and I want to be home on time for dinner, I had better have my clock synchronized with my wife's and when I engage my BSG Jump Drive, I want to arrive home, with my ship parked in the garage. Hence, "at rest with respect to the target coordinates" is far from "nonsensical"!
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But how do you synchronize the clocks? Personally I think this discussion shows the paradoxes cannot be resolved.
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As you say the only frame that matters is the frame that the person with the FTL drive is in. Instead of randomly switching from the ship 2 frame to the Earth frame, let ship 2 stay in the ship2 frame and see what happens.
"at rest with respect to the target coordinates" is nonsensical. The "target coordinates" would be an event in space-time. An event does not have a velocity, and can be described in any arbitrary frame with any velocity.
You are far too nit-picky! You just like to argue and be right.
If I'm the pilot of ship 2 and I want to be home on time for dinner, I had better have my clock synchronized with my wife's and when I engage my BSG Jump Drive, I want to arrive home, with my ship parked in the garage. Hence, "at rest with respect to the target coordinates" is far from "nonsensical"!
Are you even reading what you are writing? As Phil Stooke asked, what do you even mean by "synchronized clocks? And don't try to say "its obvious" because it is one of the most basic results of relativity that clocks cannot be synchronized in general. The target coordinates still don't have a velocity.
And why not just leave your clock as is so that you can make it for lunch years ago instead of dinner today? Choosing not to act out a paradox causing situation doesn't change the fact that your device can cause paradoxes.
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But how do you synchronize the clocks? Personally I think this discussion shows the paradoxes cannot be resolved.
"I'm from Earth, I only work in space." ;) It was synchronized before I left the house. Since neither my warp drive nor my jump drive cause time dilation, our clocks remain synchronized until I get home for dinner.
Physicists have been trying to resolve the issue of CTL paradoxes for decades. It's probably not going to be resolved on a usenet group. IMO, Lorentz transformations are the cause of the problem, because when using them, moving reference frames are arbitrary and indistinguishable. These are Math assumptions. Reality, where accelerations are used to change speed, works differently. IMO, changing the rate of my clock does not allow me to send messages backwards in time.
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But how do you synchronize the clocks? Personally I think this discussion shows the paradoxes cannot be resolved.
"I'm from Earth, I only work in space." ;) It was synchronized before I left the house. Since neither my warp drive nor my jump drive cause time dilation, our clocks remain synchronized until I get home for dinner.
Not even relevant. Go read the original scenario I described again. Making up some different scenario doesn't change mine.
IMO, Lorentz transformations are the cause of the problem, because when using them, moving reference frames are arbitrary and indistinguishable. These are Math assumptions.
They are not math assumptions, they are very fundamental and experimentally confirmed principles.
Reality, where accelerations are used to change speed, works differently. IMO, changing the rate of my clock does not allow me to send messages backwards in time.
It isn't the changing clock speeds that cause time travel, it is the FTL device. Accelerations to some extent can be handled in special relativity, at least for simple cases including resolving the "twin paradox" which really is just recognizing there are 3 inertial reference frames involved, not 2.
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Reality, where accelerations are used to change speed, works differently. IMO, changing the rate of my clock does not allow me to send messages backwards in time.
It isn't the changing clock speeds that cause time travel, it is the FTL device. Accelerations to some extent can be handled in special relativity, at least for simple cases including resolving the "twin paradox" which really is just recognizing there are 3 inertial reference frames involved, not 2.
You keep missing the point. My FTL device works by changing the rate of "my clock" and changing the length of "my ship". This what the warp field generated around my ship does. It compensates for time dilation and length contraction and thereby allows it to travel FTL without any affects of length contraction or time dilation typical of SR. Again, altering the space around my ship does not allow me to send the ship or any signals backwards in time. Your imaginary FTL device may allow it, but the one I wrote about in my paper does not. It's not relativistic, it's Newtonian. dtau=dt on this ship, my proper time matches that of my wife at home, all day, regardless of my speed. That's how FTL is done "right". :)
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The Alcubierre warp drive had the feature that dtau=dt, the proper time aboard the ship matched the same time as the folks back home. That is the "Goal"! It is what my drive was designed to do. Earth is only preferred, because that is where we come from. It could just as easily be tuned to a different home-clock, but what clock you choose is irrelevant. Time is relative to where you call "home".
But what if you change what your ship is tuned to? Wouldn't that enable time travel?
Ok, let's say you are out tooling around in your shiny new ship and you meet some aliens in deep space. Let's say you agree to warp to earth and meet up there. Problem, their ship is tuned to their home system which has a very high relative velocity with respect to earth. That causes them to arrive at earth years before you were even born. They accidentally land on your grandfather thus insuring that you were never born to invent your warp drive.
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Reality, where accelerations are used to change speed, works differently. IMO, changing the rate of my clock does not allow me to send messages backwards in time.
It isn't the changing clock speeds that cause time travel, it is the FTL device. Accelerations to some extent can be handled in special relativity, at least for simple cases including resolving the "twin paradox" which really is just recognizing there are 3 inertial reference frames involved, not 2.
You keep missing the point. My FTL device works by changing the rate of "my clock" and changing the length of "my ship". This what the warp field generated around my ship does. It compensates for time dilation and length contraction and thereby allows it to travel FTL without any affects of length contraction or time dilation typical of SR. Again, altering the space around my ship does not allow me to send the ship or any signals backwards in time. Your imaginary FTL device may allow it, but the one I wrote about in my paper does not. It's not relativistic, it's Newtonian. dtau=dt on this ship, my proper time matches that of my wife at home, all day, regardless of my speed. That's how FTL is done "right". :)
You STILL have not addressed what would happen with your device when used in the scenario I had described.
Note: the below example re-defines light-year to be distance light travels in 50 weeks (and 1 year = 50 weeks) to make the math easier.
Let me break it down with numbers. Define that Ship 1 is at rest in the Earth frame at t= 0, x = 0. At this time ship 1 activates its FTL drive, allowing it to arrive at a location in the earth frame of x = 10 light years, at time t = 5 weeks, (apparent speed of roughly 100 c). It will take 10 years before a signal from the ship upon arrival would reach Earth, but this doesn't change the time coordinate I listed in the Earth Frame for the ship's arrival. I do not know or care how much apparent time or distance was experienced by the people on ship 1, only the space-time coordinates of where ship 1 entered and exited FTL.
Now lets take another spaceship travelling away from Earth at 0.7 c. (I think I got towards/away mixed up earlier) as is traditional for simplicity, define t'=0 and x'=0 to be the coordinates in the ship2 frame of ship 1 when it had entered FTL. (Making the origins overlap is just simpler.) Now we calculate the coordinates when ship 1 exits FTL in this frame. These are x' = 13.9 light years, and t' = -483 weeks (-9.66 years).
At this point it should be obvious where the problem is going to be, but lets continue. First we should remember that as far as ship 2 cares, ship 2 is stationary, and both Earth and ship 1 are travelling away from it at 0.7c.
Ship 2 happens to be at the same place as ship 1 when ship 1 exits FTL. Ship 1 send a message to ship2. Ship 2 Then activates its FTL in the direction of Earth. Since Earth is travelling towards the origin of the ship2 frame with speed, 0.7c and will reach the origin when t'=0, the current location of Earth in the ship2 frame is x' = 6.76 light years at t' = -483 weeks, This makes Earth 7.14 light years away from ship 2. Ship 2 can cover this distance in 3.57 weeks using the same type of FTL drive that ship1 has. Lets say it is a bit slower (and account for the Earth moving away from it, and say 4 weeks.) Ship 2 exits FTL in its frame at t'=-479, and x' =6.706 (Earth has moved). In The Earth frame this corresponds to x=0 (it is at Earth) and t= -244 weeks.
Ship 2 can now send the message to that ship 1 sent to Earth nearly 5 years before ship 1 departs Earth to begin with.
You cannot just wish this problem away, and nothing you have said addresses it. Ship 2 has no reason to have "synchronized" anything with Earth, and is just relaying a message before it continues to move away from Earth/allow Earth to move away from it at 0.7 c. Neither the Earth frame nor the ship2 frame is any more valid, so the behavior of any FTL drive must be the same in both. Also note that there is no reference to what the people on either ship experience because it doesn't matter. (When talking about the ship2 frame, I am referring to a pure inertial frame of some observer initially commoving with ship2.)
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You cannot just wish this problem away, and nothing you have said addresses it. Ship 2 has no reason to have "synchronized" anything with Earth, and is just relaying a message before it continues to move away from Earth/allow Earth to move away from it at 0.7 c. Neither the Earth frame nor the ship2 frame is any more valid, so the behavior of any FTL drive must be the same in both. Also note that there is no reference to what the people on either ship experience because it doesn't matter. (When talking about the ship2 frame, I am referring to a pure inertial frame of some observer initially commoving with ship2.)
In the unprimed frame, ship 1 enters FTL at Earth, t=0, x=0, and exits FTL at t=5 weeks and x = 10 light years distance. With my proposed warp drive, the clock on ship 1 always runs at the same rate as the clock on Earth. When the ship exits FTL, Earth AND ship 1 have advanced 5 weeks into the future.
Ship 2 is moving at 0.7c and is at the same location in space-time, where ship 1 exits FTL. This is where the two ships are at the same place "at the same time", so this is where the two coordinate systems (primed and unprimed) are coincident at t=t'=0. Earth has already advanced 5 weeks into the future. So at this point, no matter how fast ship 2 goes, it can never get to Earth before ship 1 left.
edit more..
Ship 1 sends a message to ship 2 saying "we arrived". At this point, ship 2 enters FTL from their frame. In that frame, the trip only takes say t = ~3 weeks and when they exit FTL, they are at Earth and still moving at 0.7c relative to Earth. Ship 2 sends the message "we arrived", and Earth receives it, ~8 weeks after ship 1 left on the Earth calendar.
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Ship 2 is moving at 0.7c and is at the same location in space-time, where ship 1 exits FTL. This is where the two ships are at the same place "at the same time", so this is where the two coordinate systems (primed and unprimed) are coincident at t=t'=0. Earth has already advanced 5 weeks into the future. So at this point, no matter how fast ship 2 goes, it can never get to Earth before ship 1 left.
It is not t=0 in either frame when ship 1 exits FTL. You just effectively introduced 2 new frames without fully defining them, since you also have to redefine where x=0, and then you would find in the new primed frame, ship 1 left more than 9 years in the future from when it arrived. Stick to just the 2 frames, the new ones just differ from the ones I used by straight constants, and if you actually did everything consistently, the net result wouldn't change. According to Ship 2 when ship 1 exits FTL, it is still years before ship 1 had entered FTL, no matter where you choose the origin of this frame.
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Ship 2 is moving at 0.7c and is at the same location in space-time, where ship 1 exits FTL. This is where the two ships are at the same place "at the same time", so this is where the two coordinate systems (primed and unprimed) are coincident at t=t'=0. Earth has already advanced 5 weeks into the future. So at this point, no matter how fast ship 2 goes, it can never get to Earth before ship 1 left.
It is not t=0 in either frame when ship 1 exits FTL. You just effectively introduced 2 new frames without fully defining them, since you also have to redefine where x=0, and then you would find in the new primed frame, ship 1 left more than 9 years in the future from when it arrived. Stick to just the 2 frames, the new ones just differ from the ones I used by straight constants, and if you actually did everything consistently, the net result wouldn't change. According to Ship 2 when ship 1 exits FTL, it is still years before ship 1 had entered FTL, no matter where you choose the origin of this frame.
Correction: Ship 1 entered FTL at t=-5 weeks, and exited FTL at t=0. This EVENT is coincident in both frames. Ship 1 and ship 2 are at the same place, at the same time, t=t'=0. With my FTL warp drive, the clock on ship 1 is the same as the clock on Earth. What you said;
According to Ship 2 when ship 1 exits FTL, it is still years before ship 1 had entered FTL, no matter where you choose the origin of this frame.
is logically and physically impossible. If this is what the Lorentz transformation is telling you, you're doing something wrong.
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Ship 2 is moving at 0.7c and is at the same location in space-time, where ship 1 exits FTL. This is where the two ships are at the same place "at the same time", so this is where the two coordinate systems (primed and unprimed) are coincident at t=t'=0. Earth has already advanced 5 weeks into the future. So at this point, no matter how fast ship 2 goes, it can never get to Earth before ship 1 left.
It is not t=0 in either frame when ship 1 exits FTL. You just effectively introduced 2 new frames without fully defining them, since you also have to redefine where x=0, and then you would find in the new primed frame, ship 1 left more than 9 years in the future from when it arrived. Stick to just the 2 frames, the new ones just differ from the ones I used by straight constants, and if you actually did everything consistently, the net result wouldn't change. According to Ship 2 when ship 1 exits FTL, it is still years before ship 1 had entered FTL, no matter where you choose the origin of this frame.
Correction: Ship 1 entered FTL at t=-5 weeks, and exited FTL at t=0. This EVENT is coincident in both frames. Ship 1 and ship 2 are at the same place, at the same time, t=t'=0. With my FTL warp drive, the clock on ship 1 is the same as the clock on Earth. What you said;
According to Ship 2 when ship 1 exits FTL, it is still years before ship 1 had entered FTL, no matter where you choose the origin of this frame.
is logically and physically impossible. If this is what the Lorentz transformation is telling you, you're doing something wrong.
The only thing logically impossible is FTL. You seem to claim that the difference between the time ship 1 enters FTL and the time ship1 exits FTL is the same in both frames even though time is flowing differently in both frames (earth frame and ship 2 initial frame). That is illogical.
To get from my unprimed frame to yours, just subtract 5 weeks from t and 10 light years from x. To get from my primed frame to yours, add 483 weeks to t' and subtract 13.902 lightyears from x'. As they should, the effect of the results does not depend on the choice of origin.
Since you insist, lets use your 2 coordinate systems. The coordinates of the event "ship 1 enters FTL" in the unprimed frame at x = -500 light-weeks (10 light-years), t = -5 weeks
(c = 1 light-week per week)
t' = 1.4*(-5 - 0.7c*-500/c^2) = 1.4*(-5+0.7*500) = 483
x' = 1.4*(-500-0.7*-5) = -695.1 light-weeks = -13.902 light-years
Unsurprisingly, this result is exactly equivalent to what I calculated before.
The switching of past and future is expected, because FTL entrances and exits occur in a space-like interval, not a time-like one. This causes no logical problems as long as you don't have FTL travel.
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The only thing logically impossible is FTL.
Never say something is impossible because sooner or later, someone or something comes along and proves you wrong.
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The only thing logically impossible is FTL.
Never say something is impossible because sooner or later, someone or something comes along and proves you wrong.
Generally a good point, I don't like the word "impossible."
Note that I was using words to mirror WarpTech's statement. Also, "logically impossible" basically just means illogical. Under a given base assumption, it is clearly possible to determine if something is illogical. Using nothing but the principle of relativity (no preferred reference frame), you can show that FTL is illogical.
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The only thing logically impossible is FTL. You seem to claim that the difference between the time ship 1 enters FTL and the time ship1 exits FTL is the same in both frames even though time is flowing differently in both frames (earth frame and ship 2 initial frame). That is illogical.
To get from my unprimed frame to yours, just subtract 5 weeks from t and 10 light years from x. To get from my primed frame to yours, add 483 weeks to t' and subtract 13.902 lightyears from x'. As they should, the effect of the results does not depend on the choice of origin.
Since you insist, lets use your 2 coordinate systems. The coordinates of the event "ship 1 enters FTL" in the unprimed frame at x = -500 light-weeks (10 light-years), t = -5 weeks
(c = 1 light-week per week)
t' = 1.4*(-5 - 0.7c*-500/c^2) = 1.4*(-5+0.7*500) = 483
x' = 1.4*(-500-0.7*-5) = -695.1 light-weeks = -13.902 light-years
Unsurprisingly, this result is exactly equivalent to what I calculated before.
The switching of past and future is expected, because FTL entrances and exits occur in a space-like interval, not a time-like one. This causes no logical problems as long as you don't have FTL travel.
Idk, but it seems to me that your math is flawed. The proper length of the trip is the length of the path in the "rest frame" of Earth. If the distance from where ship 1 exited FTL and Earth is 500 light weeks (10 light years) in the rest frame. Then, in the frame of ship 2 passing ship 1 where it exits FTL is t=t'=0, the distance to Earth is then shorter, not longer;
L = 10 ly/1.4 = 7.1 ly
If you want to resolve the paradox, you need to make the S and S' systems coincident at the same Event in space-time. The location where ship 1 and ship 2 are at the same place, at the same time is when ship 2 receives the signal from ship 1. This is defined as the origin where the x, t coordinates of ship 1 and ship 2 are the same, where x=x'=t=t'=0. Since t=t'=0, then v*t=v*t'=0.
Now, from this point, the distance to Earth is 7.1 ly in the primed frame. Which is shorter than it is in the unprimed frame. When ship 2 engages FTL toward Earth, it will arrive at Earth in 3.57 weeks, still moving at 0.7c relative to Earth after it exits FTL. The signal will be received by Earth 8.57 weeks AFTER ship 1 left.
There is no reference frame where ship 1 and ship 2 are at the same place, but ship 2 is years in the past of ship 1. Ship 1 moving at FTL did not bring it out of FTL in the past, the FTL warp drive I propose has the clock on the ship 1 ticking at the same rate as the clock back on Earth.
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According to Ship 2 when ship 1 exits FTL, it is still years before ship 1 had entered FTL, no matter where you choose the origin of this frame.
is logically and physically impossible. If this is what the Lorentz transformation is telling you, you're doing something wrong.
It really really seems illogical doesn't it? But that really is how it works. And as long as you allow no speed faster than light then there are no paradoxes and so while it is weird it isn't illogical.
Now you can claim that relativity must be wrong in some way. But first you need to show that you understand what relativity is claiming. From the look of it you don't.
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The only thing logically impossible is FTL. You seem to claim that the difference between the time ship 1 enters FTL and the time ship1 exits FTL is the same in both frames even though time is flowing differently in both frames (earth frame and ship 2 initial frame). That is illogical.
To get from my unprimed frame to yours, just subtract 5 weeks from t and 10 light years from x. To get from my primed frame to yours, add 483 weeks to t' and subtract 13.902 lightyears from x'. As they should, the effect of the results does not depend on the choice of origin.
Since you insist, lets use your 2 coordinate systems. The coordinates of the event "ship 1 enters FTL" in the unprimed frame at x = -500 light-weeks (10 light-years), t = -5 weeks
(c = 1 light-week per week)
t' = 1.4*(-5 - 0.7c*-500/c^2) = 1.4*(-5+0.7*500) = 483
x' = 1.4*(-500-0.7*-5) = -695.1 light-weeks = -13.902 light-years
Unsurprisingly, this result is exactly equivalent to what I calculated before.
The switching of past and future is expected, because FTL entrances and exits occur in a space-like interval, not a time-like one. This causes no logical problems as long as you don't have FTL travel.
Idk, but it seems to me that your math is flawed. The proper length of the trip is the length of the path in the "rest frame" of Earth. If the distance from where ship 1 exited FTL and Earth is 500 light weeks (10 light years) in the rest frame. Then, in the frame of ship 2 passing ship 1 where it exits FTL is t=t'=0, the distance to Earth is then shorter, not longer;
L = 10 ly/1.4 = 7.1 ly
Yes, that is the current distance between ship 2 and Earth in the ship 2 frame, as you will see I had already calculated by a different method. The problem is your baseless assumption that "now" in the ship 2 frame corresponds to shortly after ship 1 left Earth. In the ship 2 frame, Earth is moving away from ship2 at 0.7 c, and will move quite a few light years in the 483 weeks that will pass before ship 1 leaves Earth.
If you want to resolve the paradox, you need to make the S and S' systems coincident at the same Event in space-time. The location where ship 1 and ship 2 are at the same place, at the same time is when ship 2 receives the signal from ship 1. This is defined as the origin where the x, t coordinates of ship 1 and ship 2 are the same, where x=x'=t=t'=0. Since t=t'=0, then v*t=v*t'=0.
I did that, as I showed picking "ship 1 exits FTL" as the origin creates the same result as picking "ship 1 enters FTL." Because as long as it is consistent why should the choice of origin matter?
Now, from this point, the distance to Earth is 7.1 ly in the primed frame. Which is shorter than it is in the unprimed frame. When ship 2 engages FTL toward Earth, it will arrive at Earth in 3.57 weeks, still moving at 0.7c relative to Earth after it exits FTL. The signal will be received by Earth 8.57 weeks AFTER ship 1 left.
The first half of this is correct, and matches what I already said. The second half makes no sense, because t=-5 is the time coordinate of ship 1 leaving earth in the unprimed frame. You never bothered to figure out what the time coordinate is in the unprimed frame (t'=483 weeks as I showed) Adding time coordinates of different reference frames is simply wrong.
There is no reference frame where ship 1 and ship 2 are at the same place, but ship 2 is years in the past of ship 1. Ship 1 moving at FTL did not bring it out of FTL in the past, the FTL warp drive I propose has the clock on the ship 1 ticking at the same rate as the clock back on Earth.
Stop talking about the clock on ship 1, I don't care what it says, it does not matter. According to ship 2, ship 1 exited FTL years before it entered it, and nothing internal to ship 1 changes that.
You say "it seems to me that your math is flawed" but you couldn't actually point to a flaw. I pointed to multiple flaws in your math.
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According to Ship 2 when ship 1 exits FTL, it is still years before ship 1 had entered FTL, no matter where you choose the origin of this frame.
is logically and physically impossible. If this is what the Lorentz transformation is telling you, you're doing something wrong.
It really really seems illogical doesn't it? But that really is how it works. And as long as you allow no speed faster than light then there are no paradoxes and so while it is weird it isn't illogical.
Now you can claim that relativity must be wrong in some way. But first you need to show that you understand what relativity is claiming. From the look of it you don't.
Now I understand why @meberbs was confused about ship 2 moving away vs moving toward the earth. In the frame of ship 2, moving away from Earth, at 0.7c, the event of ship 1 leaving Earth and entering FTL is in the future. When it turns around to deliver the message, the primed space-time axis flip to -0.7c, moving toward the Earth. In this frame, the event of ship 1 leaving Earth is in the past.
One can think of an FTL signal as being identical to an FTL ship. If ship 2 emits an FTL signal or FTL ship 3 back toward Earth, the space-time axes still flips from v to -v. In the frame of the signal and the event of ship 1 leaving Earth is still in the past. Ship 2, nor the signal it sends to Earth can travel backwards in time.
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According to Ship 2 when ship 1 exits FTL, it is still years before ship 1 had entered FTL, no matter where you choose the origin of this frame.
is logically and physically impossible. If this is what the Lorentz transformation is telling you, you're doing something wrong.
It really really seems illogical doesn't it? But that really is how it works. And as long as you allow no speed faster than light then there are no paradoxes and so while it is weird it isn't illogical.
Now you can claim that relativity must be wrong in some way. But first you need to show that you understand what relativity is claiming. From the look of it you don't.
Now I understand why @meberbs was confused about ship 2 moving away vs moving toward the earth. In the frame of ship 2, moving away from Earth, at 0.7c, the event of ship 1 leaving Earth and entering FTL is in the future. When it turns around to deliver the message, the primed space-time axis flip to -0.7c, moving toward the Earth. In this frame, the event of ship 1 leaving Earth is in the past.
One can think of an FTL signal as being identical to an FTL ship. If ship 2 emits an FTL signal or FTL ship 3 back toward Earth, the space-time axes still flips from v to -v. In the frame of the signal and the event of ship 1 leaving Earth is still in the past. Ship 2, nor the signal it sends to Earth can travel backwards in time.
Ship 2 does not accelerate or change direction before engaging its FTL drive. It is sitting in its rest frame, it doesn't even make sense to say it "turned around", since it isn't moving. Don't think about anything other than this initial rest frame or you will confuse yourself, like you have been doing all thread.
In this frame, all it does is activate its FTL drive aimed at a point just over 7 light years to the left. It arrives between 3 and 4 weeks later in this frame. However, in this frame, ship 1 does not leave Earth for over 479 more weeks.
It does not matter that the Earth is moving, except for calculating the exact distance it wants to travel in FTL, the ship isn't planning to stop on Earth.
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The only thing logically impossible is FTL.
Never say something is impossible because sooner or later, someone or something comes along and proves you wrong.
Rather than say "impossible", a better word is perhaps "undefined" or "apparently paradoxical".
In a way, "undefined" is even more damning than "impossible", because people who claim FTL is possible without defining what happens when apparent paradoxes are implimented are making a statement without meaning.
On the other hand, unlike "impossible", We can validly say FTL is undefined, and this statement will not be refuted even if in the future it becomes defined. Our statement will remain true in the context it was given, when FTL did not have this definition.
(edit)
btw, Im thinking that this topic might be better if changed specifically to trying to contrive some paradox preventing rules. Possibly even moved to the entertainment section and expressed as FTL rules for HardSF writers.
When I started the topic here I was hoping for published work about resolving paradoxes. The thread has been somewhat derailed by people who won't even admit there is an issue to discuss.
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The only thing logically impossible is FTL.
Never say something is impossible because sooner or later, someone or something comes along and proves you wrong.
Rather than say "impossible", a better word is perhaps "undefined" or "apparently paradoxical".
In a way, "undefined" is even more damning than "impossible", because people who claim FTL is possible without defining what happens when apparent paradoxes are implimented are making a statement without meaning.
On the other hand, unlike "impossible", We can validly say FTL is undefined, and this statement will not be refuted even if in the future it becomes defined. Our statement will remain true in the context it was given, when FTL did not have this definition.
Or maybe it has been defined by some one, but is buried under mountains of knowledge and we just don't realize it yet. Maybe its already defined, but in a galaxy far far away (just not here). Maybe it just hasn't yet been applied, but then again maybe it could already be applied in a galaxy far far away. Supposing it is, maybe that isn't such a great distance any more? Well at least we know that we, ourselves, don't yet know how to put it into practice if its possible. I'm sure a lot of us here hope to see it openly applied during our lifetimes if its possible. It would be quite depressing if it isn't. Let's hope.
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I think they key to understanding what WarpTech is saying is that locally he his modifying the passage of time and speed of light. Well in a way it is non-locally modifying it. The occupants should be unaware of this change in the speed of light locally.
Normally for a ship moving away as it gains speed, space time contracts for the ship and its time slows down. However for the ship occupants its time does not slow down, its the universes time that speeds up ... well (speeds up and slows down) speeds up because they end up in the future. How does this happen? It's during the contraction phase. For the space in front of the ship to contract and become closer, you must take the forward velocity of the ship and add time, and the further away the more time you add, and everything uniformly contracts. This would signify traveling into the future. So realistically you can go as fast as you want in your own ship. At first you travel mostly through space but at the c limit you begin more traveling through time/space. (more through time).
By locally stretching the ship and modifying the index instead you also appear to contract space outside to someone aboard the ship, but you do this by expanding your ship and locally increasing the speed of light (increasing your ruler w.r.t the universe). To increase the speed of light means increasing the passage of time and decreasing your mass. Having some velocity and decreasing your mass means your velocity increases but now your speed limit also increases. If you balance relativity effects and this index you can keep your index the same as some one else's far away so you both age at the same rate.
Such a method would allow you to achieve the same "apparent" relative velocity w.r.t. the universe as you would via being limited to the speed of light except now you can make the trip there and back, still being alive and having exceeded the light speed limit, and return the same linear age as your relatives when you return.
What it would take to accomplish this however is the big kahuna. I think WarpTech calls it pumping energy into the ZPF? It can probably be thought of as locally inflating the vacuum.
I'm hoping i'm not too far off and that helps clarify the concept.
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Or maybe it has been defined by some one, but is buried under mountains of knowledge and we just don't realize it yet.
That is equivalent to being undefined. The whole point of definitions is that two people can use them to converse, using words, that have agreed definitions.
(I suspect a corollary to the rule "Any internet conversation will eventually descend into semantics" is that eventually the discussion of semantics will have to descend to an attempt to define the word "defined")
It really does not need to be this confusing. What I am looking for is descriptions of what happens when someone tries to implement one of the paradoxes. How are the apparent paradoxes resolved. What. Actually. Happens.
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It really does not need to be this confusing. What I am looking for is descriptions of what happens when someone tries to implement one of the paradoxes. How are the apparent paradoxes resolved. What. Actually. Happens.
In General Relativity, the paradoxes due to assuming FTL travel indicates FTL travel won't work. You can't implement the paradox. If FTL is possible, it's new physics requiring new theories to improve on GR. Without new theories, you can't get past the paradoxes.
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In General Relativity, the paradoxes due to assuming FTL travel indicates FTL travel won't work. You can't implement the paradox. If FTL is possible, it's new physics requiring new theories to improve on GR. Without new theories, you can't get past the paradoxes.
Very possibly, but there might be loopholes. I think (just a layman's guess) one possible loophole could be to move your 'stargate' ends so far apart that the expansion of the universe puts them into otherwise causally disconnected parts of the universe. I think the paradoxes would not be implementable in that case.
There might be less extreme examples.
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In General Relativity, the paradoxes due to assuming FTL travel indicates FTL travel won't work. You can't implement the paradox. If FTL is possible, it's new physics requiring new theories to improve on GR. Without new theories, you can't get past the paradoxes.
Very possibly, but there might be loopholes. I think (just a layman's guess) one possible loophole could be to move your 'stargate' ends so far apart that the expansion of the universe puts them into otherwise causally disconnected parts of the universe. I think the paradoxes would not be implementable in that case.
There might be less extreme examples.
There would also need to be some mechanism that would prevent opening up a second "stargate" in parallel that has some relative velocity to the first. And this mechanism would need to be restricted in its ability to transmit FTL information. It might be possible, but I haven't figured out the right way to put these restrictions down formally. This causality protection mechanism would almost certainly require some new theory.
I have seen serious suggestions that if you created a closed timelike loop using wormholes, some sort of feedback mechanism would cause the wormholes to collapse. Specifically, the wikipedia pageon chonology protection references a book on GR called "Black Holes and Time Warps" which apparently proposes a specific mechanism involving vacuum fluctuations, but this sounds like it would require quantum gravity to truly analyze, which is a theory that doesn't exist yet.
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Such a method would allow you to achieve the same "apparent" relative velocity w.r.t. the universe as you would via being limited to the speed of light except now you can make the trip there and back, still being alive and having exceeded the light speed limit, and return the same linear age as your relatives when you return.
The paradoxes don't care anything for how much time passes on the ship though, it could be 1 second or 100 years, and the paradox would remain a problem. "relative velocity w.r.t. the universe" implies that there is a special frame associated with "the universe" when there isn't.
WarpTech's explanations just ignore or deny the existence of frames where the FTL travel is travel backwards in time, allowing someone in that frame to use their FTL to create a loop. He has demonstrated that he has no idea what he is talking about when it comes to special relativity, and until he understands the problem, there is no way he can address it.
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I think they key to understanding what WarpTech is saying is that locally he his modifying the passage of time and speed of light. Well in a way it is non-locally modifying it. The occupants should be unaware of this change in the speed of light locally.
But that just can't matter. The time dilation, time offset and space contractions aren't some physical effect that is mechanically caused by your motion. It is geometry. You cannot speak of being in your neighbor's house across the road without being across the road. It is nonsense to think that some kind of warp drive will let you visit your neighbor without you being across the road. Warp drive, teleporting or magic poofing just can't matter. It makes no difference.
Similarly relativity pretty much defines traveling faster than light as time travel. If you can do it then you can return home before you left. This isn't a mechanical effect of speed or acceleration that you might find some way to prevent. It is an unavoidable property of the geometry of spacetime. Warp drive, teleporting or magic poofing just can't matter.
To do it you will have to break and disprove relativity and dump that geometry. Well I'm all for that if it can be done but you first have to understand the problem.
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I think they key to understanding what WarpTech is saying is that locally he his modifying the passage of time and speed of light. Well in a way it is non-locally modifying it. The occupants should be unaware of this change in the speed of light locally.
But that just can't matter. The time dilation, time offset and space contractions aren't some physical effect that is mechanically caused by your motion. It is geometry. You cannot speak of being in your neighbor's house across the road without being across the road. It is nonsense to think that some kind of warp drive will let you visit your neighbor without you being across the road. Warp drive, teleporting or magic poofing just can't matter. It makes no difference.
Similarly relativity pretty much defines traveling faster than light as time travel. If you can do it then you can return home before you left. This isn't a mechanical effect of speed or acceleration that you might find some way to prevent. It is an unavoidable property of the geometry of spacetime. Warp drive, teleporting or magic poofing just can't matter.
To do it you will have to break and disprove relativity and dump that geometry. Well I'm all for that if it can be done but you first have to understand the problem.
If your clock ticks at the same rate at home as for you aboard the ship by locally modifying your local index K you don't return home before you left. You return as fast as you can travel, (speed no longer limited by c) and eliminate relativistic effects that limit your velocity. It appears the concept is linked to some of Harrold Puthoff's work. https://www.youtube.com/watch?v=blojNMW-Ias
One of Puthoffs papers: https://scholar.google.com/scholar?cluster=17157422968110203841&hl=en&as_sdt=0,26
I also found it somewhat amusing a ufo abductee claimant wrote equations in their sleep related to Puthoff's equations. http://synchronizeduniverse.com/STAN%20ANALYSIS3.pdf written by By Dr. Claude Swanson .
The whole problem of assuming your moving backwards in time is probably because your not eliminating relativistic effects and still assuming your exceeding c. In such a case you can go back in time but takes more than infinite energy and is impossible. Basically inverting time and space so you go back in time. You cant relativistically exceed c.
The idea of eliminating relativistic effects is that you still have relativity but as you increase your velocity and K would increase, you purposefully modify K such that it remains the same as where you left. Relativity superimposed with lowering K = constant K. Your speed can continue to increase with out an increase in mass or slowing in time but it manipulates the vacuum. Is the vacuum really manipulable in this way?
Regardless of what some think, the vacuum does appear to have associated frames, though the vacuum doesn't always have the same frame locally. Take for instance frame dragging. These define the local C speed limit of counter propagating light waves.
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The whole problem of assuming your moving backwards in time is probably because your not eliminating relativistic effects and still assuming your exceeding c. In such a case you can go back in time but takes more than infinite energy and is impossible. Basically inverting time and space so you go back in time. You cant relativistically exceed c.
It is not turning off relativistic effects for the ship that is required to fix the problem. It is turning off relativistic effects for the entire universe. Since we have observed relativistic effects, this is contradictory.
Your post reads as if you haven't read a single post in this thread from any of the people who understand relativity, including the one you quoted.
Regardless of what some think, the vacuum does appear to have associated frames,
regardless of what you think, this statement is false. This has been proven by experiment. And "frame dragging" is not some kind of exception. It does not mean one frame is special, it means that all frames (which are all equally valid) are bent by a rotating massive object.
You might want to learn what you are talking about before making statements that both prove your ignorance and make it sound like you think all physicists are idiots. (Because that is what I hear when you claim that the very basis of both special and general relativity is wrong.)
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The whole problem of assuming your moving backwards in time is probably because your not eliminating relativistic effects and still assuming your exceeding c. In such a case you can go back in time but takes more than infinite energy and is impossible. Basically inverting time and space so you go back in time. You cant relativistically exceed c.
It is not turning off relativistic effects for the ship that is required to fix the problem. It is turning off relativistic effects for the entire universe. Since we have observed relativistic effects, this is contradictory.
Your post reads as if you haven't read a single post in this thread from any of the people who understand relativity, including the one you quoted.
Regardless of what some think, the vacuum does appear to have associated frames,
regardless of what you think, this statement is false. This has been proven by experiment. And "frame dragging" is not some kind of exception. It does not mean one frame is special, it means that all frames (which are all equally valid) are bent by a rotating massive object.
You might want to learn what you are talking about before making statements that both prove your ignorance and make it sound like you think all physicists are idiots. (Because that is what I hear when you claim that the very basis of both special and general relativity is wrong.)
It's not just the ship that has its time modified. The whole reason the universe aboard the ship appears to contract is because "the universe is contracted by having your relative velocity and the further ahead the more time is added. (the further behind the more time is subtracted)" The universe is now distorted in time. You become a time traveler in the universe. If you assume the rest of the universe contracts because of relativistic effects and you assume you exceed c you travel back in time which is an erroneous assumption.
By modifying your local index you actually stretch your ruler w.r.t. the universe while still Edit: counteracting the contracting the universe. You no longer become a time traveler you become a space traveler. Your home planet is not in your same frame, yet you manipulate your frame to match your originating frame's clock. All other time in the universe passes as if you existed at home.
When you would have a gamma of 2 you might actually travel at twice the speed of light.
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It seems the problem is very similar to the Twins Paradox. See attached image I found online. I added the red and orange arrows to represent ship 1 and ship 2. However, this diagram is for 0.6c not 0.7c as we were discussing.
I added the direction of both ships after they exit FTL. This diagram shows the perspective from both sides.
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In General Relativity, the paradoxes due to assuming FTL travel indicates FTL travel won't work. You can't implement the paradox. If FTL is possible, it's new physics requiring new theories to improve on GR. Without new theories, you can't get past the paradoxes.
Very possibly, but there might be loopholes. I think (just a layman's guess) one possible loophole could be to move your 'stargate' ends so far apart that the expansion of the universe puts them into otherwise causally disconnected parts of the universe. I think the paradoxes would not be implementable in that case.
There might be less extreme examples.
I have seen serious suggestions that if you created a closed timelike loop using wormholes, some sort of feedback mechanism would cause the wormholes to collapse. Specifically, the wikipedia pageon chonology protection references a book on GR called "Black Holes and Time Warps" which apparently proposes a specific mechanism involving vacuum fluctuations, but this sounds like it would require quantum gravity to truly analyze, which is a theory that doesn't exist yet.
haha.. I spent a while looking for the pageon chronology protection. pageon = "page on". Duh. :)
I guess you mean this:
https://en.wikipedia.org/wiki/Chronology_protection_conjecture
For this thread im not to worried about theory that allows FTL. I certainly could not understand it. I was just hoping that proponents of FTL could explain what they even meant by the word, by explaining what their proposals predict you would experience if you tried to implement one of the famous paradoxes.
Im thinking that has proven unprofitable. Im actually considering reposing the question in the entertainment section as "Rules for FTL for HardSF writers". No concern for theory at all, just rules that prevent paradoxes, so a writer could create a consistant universe.
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FWIW, here's physicist Matthew Buckley's (https://twitter.com/physicsmatt) take on explaining why FTL requires giving up relativity or causality http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-time-travel
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Well you could just allow time travel but make it a subjective thing. For example you could travel back in time to meet your own grandfather. But to everyone who saw you leave you would just disappear never to be seen again. To you it would seem you were in a universe exactly like the one you left except you are in the past and your grandfather is still alive. No need to kill him since you are unlikely to be born in this universe anyway. Thus you can create no paradoxes in the universe that you leave but you still have them in the universe that you arrive in.
It would have the same character as the subjective nature of quantum wave collapse. To us out here a cat in a box can be in superposition. But inside the box the cat knows very well if it is alive or dead. As long as we and the cat are thermodynamically separated - and as a practical matter that is impossible - then we and the cat can disagree on its superposition. The cat that is alive is in some sense in a different universe as the cat that is dead and when we open the box we simply appear in a universe consistent with our observations.
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It seems the problem is very similar to the Twins Paradox. See attached image I found online. I added the red and orange arrows to represent ship 1 and ship 2. However, this diagram is for 0.6c not 0.7c as we were discussing.
I added the direction of both ships after they exit FTL. This diagram shows the perspective from both sides.
The #1 issue with that diagram is the obvious lack of symmetry. You can see that the red line travels backwards in time in the "outbound" frame, but the orange line should therefore be moving backwards in time in the Earth frame. As part of this you do not show the ship 2 as having as fast of FTL in its frame as ship 1 does.
You also somehow appear to have ship 2 travelling at light speed or close to it after its FTL leg (in its frame), rather than at rest. To me this mostly is just more evidence you don't know what you are talking about.
I attached a modified version. I included a little bit before each FTL jump as well, since the symmetry is more obvious that way. I also gave the second ship a just slightly faster FTL to show the time travel effect. The less powerful the FTL, the faster the relative velocity ship 2 needs to have to start with to enable full time travel, and you appear to have picked a set of values that would have caused ship 2 to arrive at the same time ship1 left if you had drawn the diagram consistently. (This is an interesting situation in itself, as it means for the whole journey, ship 2 would be flying directly aside ship 1, despite them moving in "opposite" directions.)
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FWIW, here's physicist Matthew Buckley's (https://twitter.com/physicsmatt) take on explaining why FTL requires giving up relativity or causality http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-time-travel
Another possible solution would be to give up free will.
https://en.wikipedia.org/wiki/Novikov_self-consistency_principle
Im not particularly enthused by that solution, but it is interesting to think what it would even look like.
If I was in a universe like that, I would buy a lottery ticket every day and then tell myself, today I am either going to win the lottery or create a paradox. In a universe like that, I guess you win the lottery.
On the other hand I have heard it is more likely to be struck by lightning than to win the lottery, so perhaps this would not be such a great idea. :)
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Another possible solution would be to give up free will.
Yes but as the wiki pointed out it isn't clear how you can justify or even define free will even without time travel. So it isn't clear you are giving up anything. I smell robot.
https://www.youtube.com/watch?v=cAwpBSuX5IM
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Sorry. Don't know the reference. If this is a reference to "Mr Robot", no spoilers please because I intend to watch that some time.
Does anyone know if you can make a single FTL jump and then always decide to implement a paradox? If not, it seems semi plausible to avoid paradoxes by making FTL only operate if no choice afterwards would cause a paradox. For example, If you have sent an observer along your route at relativistic speeds to create a paradox, it disrupts FTL and you don't make the trip. This is a bit like fate limiting free will, but more palatable since it only happens at this one point, and we are all used to having our free will limited at airports.
I realise that on one level that sounds really arbitrary. On the other hand it is not much weirder than the problem of the observer in quantum mechanics collapsing waveforms though the act of observation.
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Sorry. Don't know the reference. If this is a reference to "Mr Robot", no spoilers please because I intend to watch that some time.
Does anyone know if you can make a single FTL jump and then always decide to implement a paradox? If not, it seems semi plausible to avoid paradoxes by making FTL only operate if no choice afterwards would cause a paradox. For example, If you have sent an observer along your route at relativistic speeds to create a paradox, it disrupts FTL and you don't make the trip. This is a bit like fate limiting free will, but more palatable since it only happens at this one point, and we are all used to having our free will limited at airports.
I realise that on one level that sounds really arbitrary. On the other hand it is not much weirder than the problem of the observer in quantum mechanics collapsing waveforms though the act of observation.
Really dude? You don't recognize "The Big Bang Theory"? Your nerd cred just went negative. Watch the video I posted. It stands alone and will spoil nothing.
A single FTL jump will not cause a paradox. It will look like time travel to an observer in another frame of reference but you have a space like distance between you and your past so you can't immediately cause a paradox. To cause a paradox you have to accelerate your ship to some relative velocity to your original frame. Then when you jump home you will arrive before you left. That's where the paradoxes start.
Your suggestion to limit paradoxes sounds like the mechanism used by Dr. Who. Kind of clumsy, arbitrary and contrived and really ultimately making no sense at all.
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A single FTL jump will not cause a paradox. It will look like time travel to an observer in another frame of reference but you have a space like distance between you and your past so you can't immediately cause a paradox. To cause a paradox you have to accelerate your ship to some relative velocity to your original frame. Then when you jump home you will arrive before you left. That's where the paradoxes start.
I thought you could impliment a paradox with a single FTL trip, but I couldn't think of an example. If events A and B are synchronized by a pulse of light emitted exactly halfway between them, it does not seem that any lightspeed signal could get from A to B or vice versa in less time.
Can anyone else confirm whether or not FTL paradoxes always involve multiple FTL usages to implement?
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A single FTL jump will not cause a paradox. It will look like time travel to an observer in another frame of reference but you have a space like distance between you and your past so you can't immediately cause a paradox. To cause a paradox you have to accelerate your ship to some relative velocity to your original frame. Then when you jump home you will arrive before you left. That's where the paradoxes start.
I thought you could impliment a paradox with a single FTL trip, but I couldn't think of an example. If events A and B are synchronized by a pulse of light emitted exactly halfway between them, it does not seem that any lightspeed signal could get from A to B or vice versa in less time.
Can anyone else confirm whether or not FTL paradoxes always involve multiple FTL usages to implement?
Well maybe it can if your warp drive can warp to a point in space time that is local in space but back in time. Such a thing is usually just called a time travel machine. Time travel machines can enable effective FTL travel. Just travel back in time eight years and then go to Alpha Centauri at half the speed of light. You will effectively have gotten there instantly.
And it depends on what you mean by paradox. If you travel faster than light then an observer will see you as being in two different places at once. That seems like a paradox. But usually the word paradox is used to refer to when you interact with your own past.
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Well maybe it can if your warp drive can warp to a point in space time that is local in space but back in time. Such a thing is usually just called a time travel machine. Time travel machines can enable effective FTL travel. Just travel back in time eight years and then go to Alpha Centauri at half the speed of light. You will effectively have gotten there instantly.
And it depends on what you mean by paradox. If you travel faster than light then an observer will see you as being in two different places at once. That seems like a paradox. But usually the word paradox is used to refer to when you interact with your own past.
That is all granted and not really a concern. Neither of us can think of a way to implement a paradox with one FTL 'jump'. Im just waiting to see if anyone else can propose a way.
I think you can definitely do it with multiple instantaneous communications, even if you limit them all to a privileged reference frame. (edit: I should sit down and reconfirm that. No time at the moment)
Here is someone who thinks you can solve FTL paradoxes by restricting it to a special reference frame:
http://www.physicsguy.com/ftl/html/FTL_part4.html
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The #1 issue with that diagram is the obvious lack of symmetry. You can see that the red line travels backwards in time in the "outbound" frame, but the orange line should therefore be moving backwards in time in the Earth frame. As part of this you do not show the ship 2 as having as fast of FTL in its frame as ship 1 does.
You also somehow appear to have ship 2 travelling at light speed or close to it after its FTL leg (in its frame), rather than at rest. To me this mostly is just more evidence you don't know what you are talking about.
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Thanks for the effort. I see my errors and what you mean by symmetry. I've updated the diagrams again to show the "now" line in both frames, and what a trip would look like "at" the speed of light with a warp drive in both frames. You can see that a small increase in the speed of light is not going to cause a paradox. However, there is a forbidden zone between the two "now" lines.
The key to resolving the paradox is; the two clocks are compared when ship 1 exits FTL, whoever has elapsed the most time is correct, and the other is wrong. Using a path integral approach, we want to do the variation of the path to maximize the worldline through space-time. The maximal path is the one that is the correct path.
What causes the paradox is that Special Relative is about the "Special Case" where there is symmetry. That is when the Lorentz transformations are applied. But it's not always symmetrical. Take two observers with clocks, one far from any massive objects and one hovering near the event horizon of the black hole. From the perspective of the distant observer, the clock near the EH is running slow, experiencing gravitational time dilation. The observer near the event horizon does not see the other clock running slow, he sees it running fast! It's not symmetrical. Now, if we consider the possibility that inertial mass and gravitational mass are the same thing, and that time dilation due to gravity and time dilation due to inertia content are caused by the same thing, then these non-symmetrical situations would be the General solution, and the special case would be symmetry.
This may not be as far fetched as you think. Quantum Electrodynamics (QED) shows us that the vacuum has a spectral energy density that is as a function of frequency, f3. As a result, the EM vacuum ZPF does not exert any forces on matter and we cannot measure motion relative to this vacuum. However, this is not a unique spectral energy density! Its value is degenerate. To paraphrase P.W. Milonni; Any spectral energy proportional to f3 will work. Conclusion, the EM vacuum can have many different spectral energy densities, depending on the distribution of matter and energy in the vicinity. The rate at which matter interacts with this field causes "damping" of the wave functions. Gravity is the gradient in this damping factor. The local gravitational field sets a local baseline for the relative damping factor, and motion relative to it increases the damping rate and results in time dilation using the same means for both gravity and motion. Unfortunately, we (mis)interpret this as geometry.
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The key to resolving the paradox is; the two clocks are compared when ship 1 exits FTL, whoever has elapsed the most time is correct, and the other is wrong.
What do you not understand about the fact that the Earth frame and the ship 2 initial frame are both correct? Nothing about the ship 1 or Earth frame should cause ship 2 to be unable to FTL in its own frame as fast as ship 1 could in its own frame.
What causes the paradox is that Special Relative is about the "Special Case" where there is symmetry.
It isn't a special case where there is symmetry, it is the only case. If you find an exception to this, you would literally have to rewrite all of modern physics.
That is when the Lorentz transformations are applied. But it's not always symmetrical. Take two observers with clocks, one far from any massive objects and one hovering near the event horizon of the black hole.
There are no general relativistic effects relevant in this situation, even if there were\ it wouldn't prevent the paradox, and discussing general relativity is pointless when you don't understand special relativity.
I am also going to ignore your comments on QED, since it isn't even a tangent, a tangent would imply that it at some point touched on relevance.
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The key to resolving the paradox is; the two clocks are compared when ship 1 exits FTL, whoever has elapsed the most time is correct, and the other is wrong.
What do you not understand about the fact that the Earth frame and the ship 2 initial frame are both correct? Nothing about the ship 1 or Earth frame should cause ship 2 to be unable to FTL in its own frame as fast as ship 1 could in its own frame.
Are you sure that this is a realistic expectation? If we confine this to our own galaxy, then none of the stars that we've observed within our galaxy have speeds anywhere near 0.6c. Even if there were a planet orbiting a black hole, the last stable orbit is only v = 0.5c and any planet at 0.6c orbit would spiral into the event horizon. So I do not believe that such a situation can arise without Ship 2 having accelerated to >0.6c from a relative speed << c, relative to Earth.
What causes the paradox is that Special Relative is about the "Special Case" where there is symmetry.
It isn't a special case where there is symmetry, it is the only case. If you find an exception to this, you would literally have to rewrite all of modern physics.
I just gave you the basis of such a model. Starting from the BH at the center of the milky way, there is a "baseline" for the rate at which time passes in our galaxy, our solar system, our planet. The "local" baseline is our preferred frame and motion relative to it causes increased damping of the quantum oscillators, leading to time dilation and length contraction such that all observers measure the same value of "c", independent of their relative velocity. It doesn't rewrite ANY physics, it only re-interprets what we know based on QED, instead of the classical, fictitious geometry of empty space. You only need to consider it with an open mind.
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Are you sure that this is a realistic expectation? If we confine this to our own galaxy, then none of the stars that we've observed within our galaxy have speeds anywhere near 0.6c. Even if there were a planet orbiting a black hole, the last stable orbit is only v = 0.5c and any planet at 0.6c orbit would spiral into the event horizon. So I do not believe that such a situation can arise without Ship 2 having accelerated to >0.6c from a relative speed << c, relative to Earth.
High mass ratio photon rockets powered by matter-antimatter reactions should be able to reach such high velocities, and the relativistic velocity needed to produce a paradox also depends on the speed of your FTL, and it could be quite low. You are trying to solve this by saying "just don't do the thing that causes a paradox." This is just a non-answer.
I just gave you the basis of such a model. Starting from the BH at the center of the milky way, there is a "baseline" for the rate at which time passes in our galaxy, our solar system, our planet. The "local" baseline is our preferred frame and motion relative to it causes increased damping of the quantum oscillators, leading to time dilation and length contraction such that all observers measure the same value of "c", independent of their relative velocity. It doesn't rewrite ANY physics, it only re-interprets what we know based on QED, instead of the classical, fictitious geometry of empty space. You only need to consider it with an open mind.
You are the one who needs to open up your mind and go learn the basics of special relativity. If you pick one frame to be special, then the speed of light would not be constant between frames. You listed multiple different frames, none of which are "the one special frame", which is obvious from you having listed multiple of them. If you did actually pick a special frame, you would have to rewrite a lot of physics, and you would have a lot of experimental results that you would find impossible to explain.
Please don't talk about a theory of quantum gravity when you don't even get special relativity, it makes you sound both arrogant and ignorant.
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Are you sure that this is a realistic expectation? If we confine this to our own galaxy, then none of the stars that we've observed within our galaxy have speeds anywhere near 0.6c. Even if there were a planet orbiting a black hole, the last stable orbit is only v = 0.5c and any planet at 0.6c orbit would spiral into the event horizon. So I do not believe that such a situation can arise without Ship 2 having accelerated to >0.6c from a relative speed << c, relative to Earth.
High mass ratio photon rockets powered by matter-antimatter reactions should be able to reach such high velocities, and the relativistic velocity needed to produce a paradox also depends on the speed of your FTL, and it could be quite low. You are trying to solve this by saying "just don't do the thing that causes a paradox." This is just a non-answer.
That's not even symmetrical! If a rocket of any kind were "accelerated" to reach such a speed, you must realize that the Earth was not accelerated! One accelerated, physical work was done to it, it's energy content changed. The other did not. That's my point! What you call symmetrical is not symmetrical. You need symmetry to have a paradox. If ship 2 is a rocket that left Earth and accelerated, then Earth has the proper time, and the ship's clock is "really" slower than the Earth clock. The Earth clock is never slower than the Ship 2 clock, regardless what they think they observe. It's not symmetrical and even with FTL, they can't come back before they left.
I just gave you the basis of such a model. Starting from the BH at the center of the milky way, there is a "baseline" for the rate at which time passes in our galaxy, our solar system, our planet. The "local" baseline is our preferred frame and motion relative to it causes increased damping of the quantum oscillators, leading to time dilation and length contraction such that all observers measure the same value of "c", independent of their relative velocity. It doesn't rewrite ANY physics, it only re-interprets what we know based on QED, instead of the classical, fictitious geometry of empty space. You only need to consider it with an open mind.
You are the one who needs to open up your mind and go learn the basics of special relativity. If you pick one frame to be special, then the speed of light would not be constant between frames. You listed multiple different frames, none of which are "the one special frame", which is obvious from you having listed multiple of them. If you did actually pick a special frame, you would have to rewrite a lot of physics, and you would have a lot of experimental results that you would find impossible to explain.
Please don't talk about a theory of quantum gravity when you don't even get special relativity, it makes you sound both arrogant and ignorant.
There is no "one special frame". They are all relative. Our "local" frame is our preferred frame, because it sets the rate at which time passes on Earth. That's all I'm saying. This is perfectly consistent with the tenants of SR. It would not require re-writting any physics. It's just a different interpretation of what we know. You sound like a child when I tell you it doesn't affect physics and you insist that it does. You don't know that, you haven't done the work to claim it does, I have and it doesn't. Read my paper on QG, and try to understand it and you will see that there is no difference between gravitational time dilation and SR time dilation. The mechanism which makes this possible is the same in both phenomenon. "Geometry" is just one interpretation of it, but that's all it is; an interpretation. There are others...
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That's not even symmetrical! If a rocket of any kind were "accelerated" to reach such a speed, you must realize that the Earth was not accelerated! One accelerated, physical work was done to it, it's energy content changed. The other did not. That's my point! What you call symmetrical is not symmetrical.
After the rocket has finished accelerating, there is no way anyone on the rocket, on the Earth, or in any other inertial reference frame would be able to tell that it hadn't always been moving at that speed. The acceleration could have been to ship 1 instead, or half way to both. It doesn't matter.
And don't bring up the so-called "twin paradox." That is a case where people who arrive at a paradox fail to account for the effect of the acceleration on the time experienced by the twin who is accelerating. In this case, the paradox does not care if the people on the ship their trip as lasting 1 million years, or 1 second. All that matters is that a drive exists that can move between 2 space-like separated points.
There is no "one special frame". They are all relative.
Exactly.
Our "local" frame is our preferred frame, because it sets the rate at which time passes on Earth.
Special frame and preferred frame mean exactly the same thing in this context. There is no preferred frame.
You state one of the basic principles of relativity and contradict it in the next sentence. You don't understand why FTL is time travel even after being shown diagrams that demonstrate it clearly, when every competent physicist on the planet understands this. It would be a waste of time to read anything you write about actually complicated topics like general relativity or quantum mechanics.
there is no difference between gravitational time dilation and SR time dilation.
General relativity is just the full version of special relativity, of course time dilation is the same thing in both. You treating this statement like it is some kind of revelation or thinking that it changes anything I have already said is just further evidence that you don't understand the relevant topics.
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That's not even symmetrical! If a rocket of any kind were "accelerated" to reach such a speed, you must realize that the Earth was not accelerated! One accelerated, physical work was done to it, it's energy content changed. The other did not. That's my point! What you call symmetrical is not symmetrical.
After the rocket has finished accelerating, there is no way anyone on the rocket, on the Earth, or in any other inertial reference frame would be able to tell that it hadn't always been moving at that speed. The acceleration could have been to ship 1 instead, or half way to both. It doesn't matter.
And don't bring up the so-called "twin paradox." That is a case where people who arrive at a paradox fail to account for the effect of the acceleration on the time experienced by the twin who is accelerating. In this case, the paradox does not care if the people on the ship their trip as lasting 1 million years, or 1 second. All that matters is that a drive exists that can move between 2 space-like separated points.
There is no "one special frame". They are all relative.
Exactly.
Our "local" frame is our preferred frame, because it sets the rate at which time passes on Earth.
Special frame and preferred frame mean exactly the same thing in this context. There is no preferred frame.
You state one of the basic principles of relativity and contradict it in the next sentence. You don't understand why FTL is time travel even after being shown diagrams that demonstrate it clearly, when every competent physicist on the planet understands this. It would be a waste of time to read anything you write about actually complicated topics like general relativity or quantum mechanics.
there is no difference between gravitational time dilation and SR time dilation.
General relativity is just the full version of special relativity, of course time dilation is the same thing in both. You treating this statement like it is some kind of revelation or thinking that it changes anything I have already said is just further evidence that you don't understand the relevant topics.
I won't refer to them all but there are better ways than to throw insults. If the conversion could continue without the need to justify oneself, by insulting others, it would be of benefit to the forum. Thanks.
Because the topic of frames of space was brought up. One such detector might be a Sagnac Interferometer.
The rotation thus measured is an absolute rotation, that is, the platform's rotation with respect to an inertial reference frame.
It seems to be an absolute detector of space not rotating. If we build one in rotating space (https://en.wikipedia.org/wiki/Lense%E2%80%93Thirring_precession) (around earth maybe), and the speed of light is faster one way around than the other the Sagnac Interferometer would need to rotate at the same rate as space to not detect rotation - thus rotating with space. (Not very likely this has been done yet, but there seems to be no reason for it not to be.)
Satellites ring. An idea to verify the GR corrections to the Sagnac effect
is to make use of a ring of orbiting satellites (such as those belonging to the
GPS or to the future European Galileo system). A stationary ring configuration
of satellites can be the way to force the light beams to run in a closed circuit
around the Earth, both in co-rotating and counter-rotating direction. The time
difference in the propagation times should reproduce the effect expressed by formula
(42)-(47), once the much bigger classical Sagnac effect has been subtracted
out. Of course here too the technical details need to be thoroughly worked out.
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That's not even symmetrical! If a rocket of any kind were "accelerated" to reach such a speed, you must realize that the Earth was not accelerated! One accelerated, physical work was done to it, it's energy content changed. The other did not. That's my point! What you call symmetrical is not symmetrical.
After the rocket has finished accelerating, there is no way anyone on the rocket, on the Earth, or in any other inertial reference frame would be able to tell that it hadn't always been moving at that speed. The acceleration could have been to ship 1 instead, or half way to both. It doesn't matter.
And don't bring up the so-called "twin paradox." That is a case where people who arrive at a paradox fail to account for the effect of the acceleration on the time experienced by the twin who is accelerating. In this case, the paradox does not care if the people on the ship their trip as lasting 1 million years, or 1 second. All that matters is that a drive exists that can move between 2 space-like separated points.
Apparently we have different assumptions (realistic vs false) regarding the setup of this problem. Which is why you insist there is a paradox. You are wrong in that I do see why there is a paradox AND how to resolve it. You see only a symmetrical problem, which is like it or not, "identical" to the Twin paradox. What I'm saying that the interpretation you have is wrong. The past does not exist for anyone to travel backwards in time. Causality only requires that there be a finite coordinate speed of light, GR says that the coordinate speed of light is not constant, it's a variable around massive objects. The speed of light in high orbit is "faster" than it is on the surface of the Earth. No causality is broken by this, yet relative to a light signal in vacuum on Earth, the same signal in space far from matter travels a little faster.
In formulating this problem, Ship 1 and Ship 2 are "identical" and both originate from Earth. In accelerating Ship 2 to 0.6c, it's relative mass/energy has increased to 125% of that of Ship 1, it's clock has slowed down and it's length has contracted. Nothing changed on Ship 1, it's still in the hanger on Earth. This is not a symmetrical problem. Ship 2 is now heavier than Ship 1 because WORK was done to Ship 2 to accelerate it, that was not done to Ship 1. One clock is slowed, the other is not!
You would not say that Ship 2 can accelerate at the same rate as Ship 1, if Ship 2 were down in a gravity well, equivalent to a gravitational potential of;
2GM/r = (0.6c)2
It would not, because the two ships are in different physical-vacuum environments.
there is no difference between gravitational time dilation and SR time dilation.
General relativity is just the full version of special relativity, of course time dilation is the same thing in both. You treating this statement like it is some kind of revelation or thinking that it changes anything I have already said is just further evidence that you don't understand the relevant topics.
It specifically contradicts your belief that there is symmetry in this problem, because in GR, if Ship 2 is in a gravity well and it's clock runs slow, it does not look up at Ship 1 and see it's clock there running slow. It runs fast. Which is identical to the temporal relationship between Ship 1 and Ship 2 when Ship 2 was accelerated to 0.6c.
The space-time diagrams that I provided last night shows the trip of Ship 1 and Ship 2, at the speed "c". If these paths are slightly faster than c, Ship 2 may get to Earth at year 7 on Earth's clock instead of year 8 but, it does not cause a paradox. The paradox only occurs when you "assume" the problem is symmetrical in both frames, when in reality, it is not.
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That's not even symmetrical! If a rocket of any kind were "accelerated" to reach such a speed, you must realize that the Earth was not accelerated! One accelerated, physical work was done to it, it's energy content changed. The other did not. That's my point! What you call symmetrical is not symmetrical.
After the rocket has finished accelerating, there is no way anyone on the rocket, on the Earth, or in any other inertial reference frame would be able to tell that it hadn't always been moving at that speed. The acceleration could have been to ship 1 instead, or half way to both. It doesn't matter.
And don't bring up the so-called "twin paradox." That is a case where people who arrive at a paradox fail to account for the effect of the acceleration on the time experienced by the twin who is accelerating. In this case, the paradox does not care if the people on the ship their trip as lasting 1 million years, or 1 second. All that matters is that a drive exists that can move between 2 space-like separated points.
There is no "one special frame". They are all relative.
Exactly.
Our "local" frame is our preferred frame, because it sets the rate at which time passes on Earth.
Special frame and preferred frame mean exactly the same thing in this context. There is no preferred frame.
You state one of the basic principles of relativity and contradict it in the next sentence. You don't understand why FTL is time travel even after being shown diagrams that demonstrate it clearly, when every competent physicist on the planet understands this. It would be a waste of time to read anything you write about actually complicated topics like general relativity or quantum mechanics.
there is no difference between gravitational time dilation and SR time dilation.
General relativity is just the full version of special relativity, of course time dilation is the same thing in both. You treating this statement like it is some kind of revelation or thinking that it changes anything I have already said is just further evidence that you don't understand the relevant topics.
I won't refer to them all but there are better ways than to throw insults. If the conversion could continue without the need to justify oneself, by insulting others, it would be of benefit to the forum. Thanks.
The parts of my post you highlighted are not insults, to the contrary, they are simply statements of fact.
Would a statement that "every person in the world who isn't blind or colorblind agrees the typical color of the sky is blue" be an insult?
The other statement you highlighted was simply pointing out that if someone thinks that a basic concept in a field is an interesting new statement in that field, they probably aren't actually that familiar with the field.
If you think there was some kind of insult there, you report it to the mods, but all I did was state facts.
Also, I have no idea why you bring up the concept of rotating reference frames, that is just an irrelevant complication. As for inertial reference frames, we have Michelson-Morley type experiments that show they are all equivalent.
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That's not even symmetrical! If a rocket of any kind were "accelerated" to reach such a speed, you must realize that the Earth was not accelerated! One accelerated, physical work was done to it, it's energy content changed. The other did not. That's my point! What you call symmetrical is not symmetrical.
After the rocket has finished accelerating, there is no way anyone on the rocket, on the Earth, or in any other inertial reference frame would be able to tell that it hadn't always been moving at that speed. The acceleration could have been to ship 1 instead, or half way to both. It doesn't matter.
And don't bring up the so-called "twin paradox." That is a case where people who arrive at a paradox fail to account for the effect of the acceleration on the time experienced by the twin who is accelerating. In this case, the paradox does not care if the people on the ship their trip as lasting 1 million years, or 1 second. All that matters is that a drive exists that can move between 2 space-like separated points.
Apparently we have different assumptions (realistic vs false) regarding the setup of this problem. Which is why you insist there is a paradox. You are wrong in that I do see why there is a paradox AND how to resolve it. You see only a symmetrical problem, which is like it or not, "identical" to the Twin paradox. What I'm saying that the interpretation you have is wrong. The past does not exist for anyone to travel backwards in time. Causality only requires that there be a finite coordinate speed of light, GR says that the coordinate speed of light is not constant, it's a variable around massive objects. The speed of light in high orbit is "faster" than it is on the surface of the Earth. No causality is broken by this, yet relative to a light signal in vacuum on Earth, the same signal in space far from matter travels a little faster.
"which is like it or not, "identical" to the Twin paradox."
This statement disproves your claim that you see why there is a paradox.
The twin paradox is not a paradox, it is people misusing special relativity, and not recognizing that there are 3 relevant inertial frames that need to be considered. This situation only involves 2 relevant inertial frames, and really is a paradox if you allow FTL travel.
In formulating this problem, Ship 1 and Ship 2 are "identical" and both originate from Earth.
Both originating from Earth is both optional and irrelevant.
In accelerating Ship 2 to 0.6c, it's relative mass/energy has increased to 125% of that of Ship 1, it's clock has slowed down and it's length has contracted. Nothing changed on Ship 1, it's still in the hanger on Earth. This is not a symmetrical problem.
In ship 2's frame, everything you said about ship 2 is true about ship 1, except the hangar on Earth part. If they started in deep space with no nearby reference points, and the crews of each ship were unconscious during the acceleration, no measurement they could do onboard the ship, or by observing the other ship could tell them which one had accelerated. (They could look at far away stars and see the redshift of course, but those were all moving at different velocities to start with as well, and in no way affect the problem. )
I already said this, but I will keep repeating it until you read it, because you did not actually addres this statement:
After the rocket has finished accelerating, there is no way anyone on the rocket, on the Earth, or in any other inertial reference frame would be able to tell that it hadn't always been moving at that speed. The acceleration could have been to ship 1 instead, or half way to both. It doesn't matter.
there is no difference between gravitational time dilation and SR time dilation.
General relativity is just the full version of special relativity, of course time dilation is the same thing in both. You treating this statement like it is some kind of revelation or thinking that it changes anything I have already said is just further evidence that you don't understand the relevant topics.
It specifically contradicts your belief that there is symmetry in this problem, because in GR, if Ship 2 is in a gravity well and it's clock runs slow, it does not look up at Ship 1 and see it's clock there running slow. It runs fast. Which is identical to the temporal relationship between Ship 1 and Ship 2 when Ship 2 was accelerated to 0.6c.
Except there is no gravity well in this problem. In this problem as stated, ship 2 does see ship 1's clock running slow. As I said before go setup this problem by sending both ships off in opposite directions at c/3 (to get 0.6 relative). They are all equivalent, and once the acceleration is done, there is no way to tell it ever happened.
The space-time diagrams that I provided last night shows the trip of Ship 1 and Ship 2, at the speed "c". If these paths are slightly faster than c, Ship 2 may get to Earth at year 7 on Earth's clock instead of year 8 but, it does not cause a paradox. The paradox only occurs when you "assume" the problem is symmetrical in both frames, when in reality, it is not.
Your so called "solutions" are just to not act out the problem. You have suggested adding a gravity well when there is none. You have also just turned down the effectiveness of the FTL drives to almost nothing, without having the ships actually have enough relative velocity for the given amount of FTL to illustrate the paradox.
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FWIW, here's physicist Matthew Buckley's (https://twitter.com/physicsmatt) take on explaining why FTL requires giving up relativity or causality http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-time-travel
Hey hop, meberbs, and everyone here with decent respect for relativity.
I have known for a long time how to demonstrate the FTL paradox using an instantaneous communicator and multiple FTL messages using different frames, but someone convinced me recently that you could create a paradox with just one FTL message. (It might well be one of you two).
Failing that, I was sure at least that we couldn't solve the problem just by limiting all FTL travel WRT to a single reference frame.
Im less sure now. I have looked through all the examples and they all seem to use FTL in two reference frames to cause the paradox.
Here is someone who thinks you can solve FTL paradoxes by restricting it to a special reference frame:
http://www.physicsguy.com/ftl/html/FTL_part4.html
And going back to hop's link, I notice the physicist says: "So you see the problem: if we could just say that there was only one frame of reference where we needed to set up cause and effect, then we could have FTL without worrying about causality. However, there is no special frame of reference, there cannot be one if relativity is to be true." .. It is almost like he is saying yes, you could solve it by limiting FTL to a special reference frame, if you could choose one. Also, his paradox example, like mine, talks of using two FTL messages relative to different frames.
Can anyone think of a clear example that FTL with just one message, or failing that, wrt to just one special reference frame (eg the CMB rest frame), will still create a paradox?
Im not worried about how or why such a phenomenon could exist, just if it can be described without a paradox.
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Also, I have no idea why you bring up the concept of rotating reference frames, that is just an irrelevant complication. As for inertial reference frames, we have Michelson-Morley type experiments that show they are all equivalent.
That's right a rotating reference frame that rotates at a very specific velocity. And an event horizon's reference frame appears to move at the speed of light.
Some of the paradox is discussed here: http://www.theculture.org/rich/sharpblue/archives/000089.html . As the observer accelerates their space and time lines converge on the light cone.
(http://www.theculture.org/rich/sharpblue/images/lorentz.png)
Their space now passes through time. Near the speed of light length contraction occurs because further back in space more time is subtracted from the velocity away. What is behind the ship represents the past. What is ahead of the ship represents the future. The space ahead of the ship is length contracted because time is added to the relative velocity the further away an object is. Space now represents the past and the future. You can not travel into the past because if you turn around to travel to the past, the past becomes the future via your velocity and time.
Notice how their ansible is pointed to the past behind the ship. This is key.
(http://www.theculture.org/rich/sharpblue/images/secondtransmission.png)
The next ansible is pointed to the future, of the ship at near c.
I have my doubts that by having an ansible, and accelerating one can point it to an object in ones past/future and communicate with the past/future. I suspect if such a thing exists, it would only communicate with the immediate present where they presently exist. If this is the case, their communication line into the past/future is erroneous.
(http://www.theculture.org/rich/sharpblue/images/causalityviolation.png)
Take a quantum entanglement that seems to be instantaneous. Now send one of the charges away at near light speed. When its wave form collapses the signal should instantaneously go into the past (which I doubt). Wait, how do you entangle two charges and have them not exist in the same light cone...
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Can anyone think of a clear example that FTL with just one message, or failing that, wrt to just one special reference frame (eg the CMB rest frame), will still create a paradox?
Im not worried about how or why such a phenomenon could exist, just if it can be described without a paradox.
As for the number of messages needed, I believe it is always 2, when you are talking about FTL between 2 spacelike separated points in spacetime.
If you take some x distance away on a spacetime diagram, and draw a line straight down, you pass though multiple regions:
-in the forward light cone, everything is normal. (relativity at least allows long journeys to feel shorter to those on the ship)
-in the spacelike region, you start creating paradoxes if you have an equivalent device moving at some relative velocity to the first device, with the required relative velocity decreasing as you approach your time axis.
-When you get below the time axis, it is easy to see that such travel would allow paradoxes without a second device moving with relative velocity.
-You keep needing a second FTL transmission to cause a paradox until you et into your past light cone, where you can start causing a paradox with a conventional signal.
As for a consistent way to implement FTL, I have not done the math to fully work this out yet, but here are my thoughts:
I believe it is correct that it can be done by picking one reference frame to be the ultimate arbiter of "forward in time" for the entire universe. Every experiment we have done says that this is not out universe, but restricting it so that no FTL drive can move backwards in time in the preferred frame should prevent paradoxes. This also contradicts the most basic principle in relativity, so I am not sure exactly what else would have to change in physics, probably things like the speed of light would only truly be constant in one frame (or maybe the concept of aether would need to be brought back), also relativistic effects if they still exist at all would probably have to be tied to velocity in the special frame. If you are just writing interstellar hard sci-fi, picking a preferred frame for FTL should be good enough. (If you are going to pick a special frame, the center of the galaxy is the closest object you could tie it to that would seem believable, really it should just be some arbitrary frame that even our galaxy has some velocity relative to.)
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Take a quantum entanglement that seems to be instantaneous. Now send one of the charges away at near light speed. When its wave form collapses the signal should instantaneously go into the past (which I doubt). Wait, how do you entangle two charges and have them not exist in the same light cone...
They will exist within the same light cone as the entanglement event, but if they have been moved apart from each other, their current light cone will no longer include each other.
To picture this, imagine a light cone far down in the last picture in your post to represent the light cone of the entanglement event.
Also the problem with using quantum for this is the no-communication theorem. The measurement of the entangled particle will just look like random noise to someone on either side until they get sent a classical, slower than light message from the person on the other end.
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What is it with you clever people feeling you have to throw in the occasion insult?
It's amazing to see, but running a site with a forum this size, you really can say it's "mainly" the cleverer the member, the more likely they are to act like they are on some sort of throne of intelligence and us mere fools need to peer review our responses before daring to bother the King. ;D
Stop it. This forum has rules for everyone, regardless of how many degrees you may have.
Now where's my warp speed?
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That's not even symmetrical! If a rocket of any kind were "accelerated" to reach such a speed, you must realize that the Earth was not accelerated! One accelerated, physical work was done to it, it's energy content changed. The other did not. That's my point! What you call symmetrical is not symmetrical.
After the rocket has finished accelerating, there is no way anyone on the rocket, on the Earth, or in any other inertial reference frame would be able to tell that it hadn't always been moving at that speed. The acceleration could have been to ship 1 instead, or half way to both. It doesn't matter.
And don't bring up the so-called "twin paradox." That is a case where people who arrive at a paradox fail to account for the effect of the acceleration on the time experienced by the twin who is accelerating. In this case, the paradox does not care if the people on the ship their trip as lasting 1 million years, or 1 second. All that matters is that a drive exists that can move between 2 space-like separated points.
Apparently we have different assumptions (realistic vs false) regarding the setup of this problem. Which is why you insist there is a paradox. You are wrong in that I do see why there is a paradox AND how to resolve it. You see only a symmetrical problem, which is like it or not, "identical" to the Twin paradox. What I'm saying that the interpretation you have is wrong. The past does not exist for anyone to travel backwards in time. Causality only requires that there be a finite coordinate speed of light, GR says that the coordinate speed of light is not constant, it's a variable around massive objects. The speed of light in high orbit is "faster" than it is on the surface of the Earth. No causality is broken by this, yet relative to a light signal in vacuum on Earth, the same signal in space far from matter travels a little faster.
"which is like it or not, "identical" to the Twin paradox."
This statement disproves your claim that you see why there is a paradox.
The twin paradox is not a paradox, it is people misusing special relativity, and not recognizing that there are 3 relevant inertial frames that need to be considered. This situation only involves 2 relevant inertial frames, and really is a paradox if you allow FTL travel.
No, it involves 3 relevant frames as soon as Ship 2 heads back toward Earth to cause the paradox. The paradox occurs for the same reason, "misusing special relativity, and not recognizing that there are 3 relevant inertial frames..." You're only considering 2 frames, and assuming the situation is symmetrical. That is the same thing as the twin paradox. The twin paradox teaches us that the problem is NOT symmetrical, that one clock is running slow and the other is not, and what they "see" out the window is an optical illusion. Which is verified when the traveling twin returns home to find his twin older than he is.
In formulating this problem, Ship 1 and Ship 2 are "identical" and both originate from Earth.
Both originating from Earth is both optional and irrelevant.
In accelerating Ship 2 to 0.6c, it's relative mass/energy has increased to 125% of that of Ship 1, it's clock has slowed down and it's length has contracted. Nothing changed on Ship 1, it's still in the hanger on Earth. This is not a symmetrical problem.
In ship 2's frame, everything you said about ship 2 is true about ship 1, except the hangar on Earth part. If they started in deep space with no nearby reference points, and the crews of each ship were unconscious during the acceleration, no measurement they could do onboard the ship, or by observing the other ship could tell them which one had accelerated. (They could look at far away stars and see the redshift of course, but those were all moving at different velocities to start with as well, and in no way affect the problem. )
I already said this, but I will keep repeating it until you read it, because you did not actually addres this statement:
After the rocket has finished accelerating, there is no way anyone on the rocket, on the Earth, or in any other inertial reference frame would be able to tell that it hadn't always been moving at that speed. The acceleration could have been to ship 1 instead, or half way to both. It doesn't matter.
It does matter if you want to resolve the paradox. It doesn't matter if you want to continue believing that there is a paradox and time-travel is feasible. True, there is no way to tell while the two ships are moving away from each other, but if Ship 2 returns to Earth, FTL or otherwise, it requires that 3rd inertial reference frame. It still finds the clock on Earth has elapsed more time than theirs and their perception of symmetry was WRONG. The vacuum around the Earth is our baseline. Motion relative to this background causes time dilation and length contraction, relative to Earth. The center of the galaxy is another baseline. Choose your baseline to be anywhere you like, but once you do, you must keep the same baseline when discussing the motion of Ship 1 and Ship 2. You can't assume it is symmetrical, that's the same as changing the baseline you started with. (resetting your zero to be something else)
there is no difference between gravitational time dilation and SR time dilation.
General relativity is just the full version of special relativity, of course time dilation is the same thing in both. You treating this statement like it is some kind of revelation or thinking that it changes anything I have already said is just further evidence that you don't understand the relevant topics.
It specifically contradicts your belief that there is symmetry in this problem, because in GR, if Ship 2 is in a gravity well and it's clock runs slow, it does not look up at Ship 1 and see it's clock there running slow. It runs fast. Which is identical to the temporal relationship between Ship 1 and Ship 2 when Ship 2 was accelerated to 0.6c.
Except there is no gravity well in this problem. In this problem as stated, ship 2 does see ship 1's clock running slow. As I said before go setup this problem by sending both ships off in opposite directions at c/3 (to get 0.6 relative). They are all equivalent, and once the acceleration is done, there is no way to tell it ever happened.
The space-time diagrams that I provided last night shows the trip of Ship 1 and Ship 2, at the speed "c". If these paths are slightly faster than c, Ship 2 may get to Earth at year 7 on Earth's clock instead of year 8 but, it does not cause a paradox. The paradox only occurs when you "assume" the problem is symmetrical in both frames, when in reality, it is not.
Your so called "solutions" are just to not act out the problem. You have suggested adding a gravity well when there is none. You have also just turned down the effectiveness of the FTL drives to almost nothing, without having the ships actually have enough relative velocity for the given amount of FTL to illustrate the paradox.
Not true. If Ship 2 returns instantaneously to Earth, it would get there in year 5, not year 4 in Earth's frame. The ship's clock is slow, Earth's clock is not, the situation is not symmetrical.
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No, it involves 3 relevant frames as soon as Ship 2 heads back toward Earth to cause the paradox.
What is the third frame? What velocity is it moving at relative to any other given frame?
The paradox does not care what length of time is experienced by ship 2, only that in its initial frame, which is no more or less special than the frame ship 1 started in, it travels at a sufficient FTL velocity.
I am running out of ways to state that there is nothing special about the ship 1 initial frame or the ship 2 initial frame. You have repeatedly ignored my suggestion to consider the problem from the perspective of both ships having initially been accelerated from a central point.
Another question you either missed or ignored is: What is different about ship 2's frame? What experiment can they run that tells them that they have been accelerated at some point in the past? Why would their FTL drive run much slower than ship 1's?
Not true. If Ship 2 returns instantaneously to Earth, it would get there in year 5, not year 4 in Earth's frame. The ship's clock is slow, Earth's clock is not, the situation is not symmetrical.
You are defining the Earth's frame as the only correct reference frame in the universe, this is simply contradictory to all of relativity.
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No, it involves 3 relevant frames as soon as Ship 2 heads back toward Earth to cause the paradox.
What is the third frame? What velocity is it moving at relative to any other given frame?
The 3rd frame is the frame in which Ship 2 is now moving "toward" the Earth, not away from it. The velocity can be anything. It can be instantaneous travel taking 0 time, the Earth's clock will still have elapsed more time than Ship 2, which "was" accelerated to 0.6c moving away from Earth.
The paradox does not care what length of time is experienced by ship 2, only that in its initial frame, which is no more or less special than the frame ship 1 started in, it travels at a sufficient FTL velocity.
I am running out of ways to state that there is nothing special about the ship 1 initial frame or the ship 2 initial frame. You have repeatedly ignored my suggestion to consider the problem from the perspective of both ships having initially been accelerated from a central point.
Another question you either missed or ignored is: What is different about ship 2's frame? What experiment can they run that tells them that they have been accelerated at some point in the past? Why would their FTL drive run much slower than ship 1's?
I didn't ignore it. I said that Ship 2 started on Earth and was accelerated to 0.6c moving away from Earth. This "work" that was done to Ship 2 puts it in a higher-energy relative to Earth, in which it's clock runs show. That is what is different about ship 2's frame.
What experiment can they run? I said, they can return to Earth and find that the twin left behind has aged more. That proves the situation is not symmetrical. It can't be done remotely, they have to bring the two clocks back together to ompare them "accurately".
Why would their FTL drive be slower than ship 1's? Because ship 2 was accelerated and has a higher relative mass/energy content than ship 1. Therefore, it takes more Work to accelerate it back toward the Earth, than it does for Ship 1 to leave Earth.
Not true. If Ship 2 returns instantaneously to Earth, it would get there in year 5, not year 4 in Earth's frame. The ship's clock is slow, Earth's clock is not, the situation is not symmetrical.
You are defining the Earth's frame as the only correct reference frame in the universe, this is simply contradictory to all of relativity.
No, that's your assumption. I'm explaining that if you start from rest within our galaxy, you are not moving very fast relative to Earth, v << c to begin with. If you start from rest near "Sagittarius A", that would be your correct reference frame. If you start at rest on Proxima Centauri, then that is your correct reference frame. It's all relative, but they are not all the same! Basically what I'm saying is that you can have inertial reference frames, with different vacuum spectral energy densities, different scaling of rulers, clocks, matter and energy. All inertial frames are NOT created equally.
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If Ship 2 returns instantaneously to Earth
That word, instantaneous...that's tricky. By instantaneous, I think you mean simultaneously in 2 different places. However, what is simultaneous in one reference frame will not in general be simultaneous in other reference frames. So, when you say instantaneously, you're already choosing a specific reference frame, and that isn't how special relativity works because it says that all inertial reference frames are equally valid. What's instantaneous in one reference frame (say Earth's) happens in a different order in different reference frames. In one, your space ship shows up at Earth before it left, and in another, it shows up after it left. So, you only need a single FTL teleportation event to cause a paradox, that is, arriving before you left (and physically existing twice in the same time line in a valid reference frame).
https://en.wikipedia.org/wiki/Relativity_of_simultaneity (https://en.wikipedia.org/wiki/Relativity_of_simultaneity)
The Wikipedia page on the Twin Paradox goes into a lot of detail about the symmetry and asymmetry of the traveling twins, and might help one understand the subtleties of the problem. In summary, the system IS symmetric at all times except when the spaceship either accelerates or decelerates or otherwise changes reference frames, but that's what makes the difference when the spaceship returns. When the spaceship is just coasting along at 0.7c, time is going slower on the spaceship compared to Earth AND ALSO time is going slower on Earth compared to the spaceship. Yeah, physics is cool like that.
https://en.wikipedia.org/wiki/Twin_paradox (https://en.wikipedia.org/wiki/Twin_paradox)
It seems to me the easiest way around FTL paradoxes is to say that Einstein was wrong and special relativity is incomplete (see E.E. Doc Smith and many others since) in whatever way is most convenient for the plot. Another option is to live with special relativity and note that the limit of the speed of light doesn't actually limit how far you can hypothetically travel in a year of your local time. A space ship's "effective speed" through the Galaxy is only limited by energy and the Gs you can pull, since at relativistic speeds distance is compressed. See Forever War or similar works. Just be prepared to outlive your twin.
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No, it involves 3 relevant frames as soon as Ship 2 heads back toward Earth to cause the paradox.
What is the third frame? What velocity is it moving at relative to any other given frame?
The 3rd frame is the frame in which Ship 2 is now moving "toward" the Earth, not away from it. The velocity can be anything. It can be instantaneous travel taking 0 time, the Earth's clock will still have elapsed more time than Ship 2, which "was" accelerated to 0.6c moving away from Earth.
Lets assume it is instantaneous for simplicity. What frame is it instantaneous in though? The only sensible answer is the ship 2 frame, but in this frame ship 1 hasn't left yet, so it produces the paradox.
Also, despite your claim to the contrary, you still are ignoring considering the problem from any case other than "ship 2 was accelerated." All of the cases have the same result of time travel.
The paradox does not care what length of time is experienced by ship 2, only that in its initial frame, which is no more or less special than the frame ship 1 started in, it travels at a sufficient FTL velocity.
I am running out of ways to state that there is nothing special about the ship 1 initial frame or the ship 2 initial frame. You have repeatedly ignored my suggestion to consider the problem from the perspective of both ships having initially been accelerated from a central point.
Another question you either missed or ignored is: What is different about ship 2's frame? What experiment can they run that tells them that they have been accelerated at some point in the past? Why would their FTL drive run much slower than ship 1's?
I didn't ignore it. I said that Ship 2 started on Earth and was accelerated to 0.6c moving away from Earth. This "work" that was done to Ship 2 puts it in a higher-energy relative to Earth, in which it's clock runs show. That is what is different about ship 2's frame.
Ship 2 is at rest in the ship 2 frame, and ship 1 has the higher energy, and nothing is special about Earth.
What experiment can they run? I said, they can return to Earth and find that the twin left behind has aged more. That proves the situation is not symmetrical. It can't be done remotely, they have to bring the two clocks back together to ompare them "accurately".
All that experiment would tell them is that after they woke up, they accelerated towards Earth.
Ship 1 could run the same experiment and accelerate the same amount to "catch up" to ship 2 and they would find that ship 1 had had the slow clock.
Why would their FTL drive be slower than ship 1's? Because ship 2 was accelerated and has a higher relative mass/energy content than ship 1. Therefore, it takes more Work to accelerate it back toward the Earth, than it does for Ship 1 to leave Earth.
No it would take the same amount of work.
No, that's your assumption. I'm explaining that if you start from rest within our galaxy, you are not moving very fast relative to Earth, v << c to begin with. If you start from rest near "Sagittarius A", that would be your correct reference frame. If you start at rest on Proxima Centauri, then that is your correct reference frame. It's all relative, but they are not all the same! Basically what I'm saying is that you can have inertial reference frames, with different vacuum spectral energy densities, different scaling of rulers, clocks, matter and energy. All inertial frames are NOT created equally.
Except the very principle of relativity is that ALL frames are created equally. You cannot claim that Earth and Sagittarius A are both correct and then say that not all are equal.
You have put no restriction on how fast your FTL can go, explicitly referencing instantaneous travel. Even the slightest difference in speed will lead to a paradox as you approach instantaneous travel. Try it with the Earth orbital speed (30 km/s) and effectively instantaneous travel between here and some point, say 10 light years away.
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No, it involves 3 relevant frames as soon as Ship 2 heads back toward Earth to cause the paradox.
What is the third frame? What velocity is it moving at relative to any other given frame?
The 3rd frame is the frame in which Ship 2 is now moving "toward" the Earth, not away from it. The velocity can be anything. It can be instantaneous travel taking 0 time, the Earth's clock will still have elapsed more time than Ship 2, which "was" accelerated to 0.6c moving away from Earth.
Lets assume it is instantaneous for simplicity. What frame is it instantaneous in though? The only sensible answer is the ship 2 frame, but in this frame ship 1 hasn't left yet, so it produces the paradox.
Also, despite your claim to the contrary, you still are ignoring considering the problem from any case other than "ship 2 was accelerated." All of the cases have the same result of time travel.
The paradox does not care what length of time is experienced by ship 2, only that in its initial frame, which is no more or less special than the frame ship 1 started in, it travels at a sufficient FTL velocity.
I am running out of ways to state that there is nothing special about the ship 1 initial frame or the ship 2 initial frame. You have repeatedly ignored my suggestion to consider the problem from the perspective of both ships having initially been accelerated from a central point.
Another question you either missed or ignored is: What is different about ship 2's frame? What experiment can they run that tells them that they have been accelerated at some point in the past? Why would their FTL drive run much slower than ship 1's?
I didn't ignore it. I said that Ship 2 started on Earth and was accelerated to 0.6c moving away from Earth. This "work" that was done to Ship 2 puts it in a higher-energy relative to Earth, in which it's clock runs show. That is what is different about ship 2's frame.
Ship 2 is at rest in the ship 2 frame, and ship 1 has the higher energy, and nothing is special about Earth.
What experiment can they run? I said, they can return to Earth and find that the twin left behind has aged more. That proves the situation is not symmetrical. It can't be done remotely, they have to bring the two clocks back together to ompare them "accurately".
All that experiment would tell them is that after they woke up, they accelerated towards Earth.
Ship 1 could run the same experiment and accelerate the same amount to "catch up" to ship 2 and they would find that ship 1 had had the slow clock.
Why would their FTL drive be slower than ship 1's? Because ship 2 was accelerated and has a higher relative mass/energy content than ship 1. Therefore, it takes more Work to accelerate it back toward the Earth, than it does for Ship 1 to leave Earth.
No it would take the same amount of work.
No, that's your assumption. I'm explaining that if you start from rest within our galaxy, you are not moving very fast relative to Earth, v << c to begin with. If you start from rest near "Sagittarius A", that would be your correct reference frame. If you start at rest on Proxima Centauri, then that is your correct reference frame. It's all relative, but they are not all the same! Basically what I'm saying is that you can have inertial reference frames, with different vacuum spectral energy densities, different scaling of rulers, clocks, matter and energy. All inertial frames are NOT created equally.
Except the very principle of relativity is that ALL frames are created equally. You cannot claim that Earth and Sagittarius A are both correct and then say that not all are equal.
You have put no restriction on how fast your FTL can go, explicitly referencing instantaneous travel. Even the slightest difference in speed will lead to a paradox as you approach instantaneous travel. Try it with the Earth orbital speed (30 km/s) and effectively instantaneous travel between here and some point, say 10 light years away.
In the problem formulated my way and not all the other ways you're trying to drag us into; the clock on Ship 2 runs slow. The clock on Earth/Ship 1 does not. (Again, assuming my FTL warp drive in my JBIS paper where, when FTL is engaged, the rate of the clock on the ship does not change rate relative to it's rate before FTL was engaged.)
At the time Ship 1 reaches Ship 2, what I mean by "instantaneous" is, that if the FTL trip took 0 time for Ship 1, it would leave Earth at Year 5 and arrive at Ship 2's location, when Ship 2's clock is at Year 4. Likewise, when Ship 2 sees Ship 1 arrive, they instantaneously travel back to Earth. The clock on Earth is at Year 5, the clock on Ship 2 is still Year 4. Neither Ship 1 nor Ship 2 took any time to travel the 3 light years between them, but the clocks do not agree. There is no paradox, we can't go any faster than "instantaneous", and we can never go backwards in time in either frame.
IMO, this model makes perfect sense, there are no paradoxes and it is consistent with General Relativity. Symmetry is not required, it's the "special" case, and because of its specialness, SR leads to paradoxes. The principle that all inertial frames are equal is an "assumption" of the the theory of SR. It is what makes SR Special, but it's not realistic.
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KelvinZero,
Clearly what you need is a way to visualize spacetime geometry so that you can answer these questions for yourself.
Let's start with Newtonian space and the Galilean transform. Imagine a vast frozen lake and ice skaters on it. The skate blades can bite into the ice allowing the skaters to push against it and change their direction of travel. But imagine the ice was infinitely hard and had zero friction. The only way the skaters can change directions is to collide with each other and push off each other. Energy and momentum is conserved and velocity only exists relative to some point of view. It's like the ice is an illusion. Now imagine that in three dimensions with space.
For the geometry of relativity I like Brian Green's idea of a loaf of bread and now slices. Let's reduce space dimensions to two again and use the third dimension for time. That way we can imagine the present as a slice of bread. Let's make it raisin bread so that events can be marked with raisins. There are many slices of bread that contain past events and many slices of bread containing future events. This loaf of bread is a model of spacetime containing all the events that happen in the entire universe past, present and future. The now slice is the slice of all events that are happening now. These are all the events that you could visit if you could travel instantaneously. All the others are in the past and out of reach or in the future and you will have to wait till they happen in the now.
Now relativity does a strange thing to the now slice. Motion causes a rotation of the space-time axis.If we are traveling with respect to each other then our now slices are tilted with respect to each other. My now slice contains events both in your future and in your past. That means that with instantaneous travel I could visit both your future and your past. I could then deliver a message from your future to your past thus causing a paradox.
Now can a single instantaneous message or trip cause a paradox? No because the only points available for you to go to are the points in your now slice. In order to time travel you have to accelerate to some velocity with respect to that now slice. Then your now slice has a tilt with respect to the original now slice. This will allow you to travel to your own past. Paradox.
Can you prevent time travel by limiting your FTL to with respect to a single frame of reference? Well yes but that's like having a time traveling machine in the room and just deciding not to use it. It will not for example prevent aliens from using time travel to screw with our past. FTL travel makes time travel possible under relativity. Choosing not to use it does not change anything. Paradoxes are but a decision away.
Can we avoid paradoxes if the physics of the universe established a universal frame of reference? Well yes but then it makes no sense to worry about what relativity has to say about it since relativity is wrong. Also just about all of modern physics would be horribly wrong. Could you do it while reproducing all the correct predictions of our current wrong physics? Maybe but it would be horribly complex and very very difficult to do. I wouldn't even know where to begin.
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KelvinZero,
Clearly what you need is a way to visualize spacetime geometry so that you can answer these questions for yourself.
...
Now can a single instantaneous message or trip cause a paradox? No because the only points available for you to go to are the points in your now slice. In order to time travel you have to accelerate to some velocity with respect to that now slice. Then your now slice has a tilt with respect to the original now slice. This will allow you to travel to your own past. Paradox.
Can you prevent time travel by limiting your FTL to with respect to a single frame of reference? Well yes but that's like having a time traveling machine in the room and just deciding not to use it. It will not for example prevent aliens from using time travel to screw with our past. FTL travel makes time travel possible under relativity. Choosing not to use it does not change anything. Paradoxes are but a decision away.
Can we avoid paradoxes if the physics of the universe established a universal frame of reference? Well yes but then it makes no sense to worry about what relativity has to say about it since relativity is wrong. Also just about all of modern physics would be horribly wrong. Could you do it while reproducing all the correct predictions of our current wrong physics? Maybe but it would be horribly complex and very very difficult to do. I wouldn't even know where to begin.
Hi ppnl,
I have the basic understanding that allows me to demonstrate these paradoxes using two 'instantaneous' messages using different frames. Normally I use a synchronizing pulse sent out from exactly halfway between to points to define 'instantaneous' and then I explore what that looks like in different frames of reference, using "the speed of light is the same for all observers".
Someone had convinced me recently that you could cause a paradox with a single ftl message. After all, a spaceship a mere kilometer long rushing past you at near the speed of light could have its front end a thousand years lagged in time compared to it's back end. When I recently tried to draw it out on paper, although yes, I was clearly sending messages back in time, it seemed impossible to exploit this by a lightspeed message between the two end points. The same geometry that says the front of the ship is lagged in time also explains why any message would take more than a thousand years to catch up to it.
I think we are on about the same page there.
I think I misexplained myself when I said "Im not worried about how or why such a phenomenon could exist, just if it can be described without a paradox."
I don't mean "I am ok with any hypothetical universe, so long as it is self consistent". It absolutely must not contradict what we already observe about the real world, ie relativity.
Given that, Im prepared to entertain all sorts of arbitrary rules to prevent paradoxes, such as impenetrable walls suddenly appearing, preventing relativistic travel in a defined region/period. Postulating a wall is not the same as pretending relativity is no longer a thing.
It just has to be describable in this universe without having paradoxes that mean you haven't really described anything.
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Can we avoid paradoxes if the physics of the universe established a universal frame of reference? Well yes but then it makes no sense to worry about what relativity has to say about it since relativity is wrong. Also just about all of modern physics would be horribly wrong. Could you do it while reproducing all the correct predictions of our current wrong physics? Maybe but it would be horribly complex and very very difficult to do. I wouldn't even know where to begin.
Rather than attempting to match everything I would be curious if there is some minimal set of experiments to throw out that would again allow a consistent description that isn't overly complex. This might not be reasonable to do either, since so many parts of physics are intertwined (Electrodynamics is inherently relativistic for example).
I don't mean "I am ok with any hypothetical universe, so long as it is self consistent". It absolutely must not contradict what we already observe about the real world, ie relativity.
Given that, Im prepared to entertain all sorts of arbitrary rules to prevent paradoxes, such as impenetrable walls suddenly appearing, preventing relativistic travel in a defined region/period. Postulating a wall is not the same as pretending relativity is no longer a thing.
It just has to be describable in this universe without having paradoxes that mean you haven't really described anything.
I have some had some ideas on where to start with that (how far apart do you keep your wormholes, what relative velocity, etc.), but it will take some time before I can flesh it out, and it may get incredibly complex for more than 2 wormholes, so I might not be able to do it in general.
Note: I say wormholes for FTL, because for any given FTL travel, I think it can be treated as a wormhole between 2 events in space-time for the purpose of determining causality.
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In the problem formulated my way and not all the other ways you're trying to drag us into;
You are the one who "changed" the problem by insisting that ship 2 start at Earth and accelerate before the problem begins. (There is actually no difference to the problem either way, but by starting ship 2 at Earth you are hand-waving that Earth is the preferred reference frame for the universe, which you then deny before repeating that the Earth frame is special.)
the clock on Ship 2 runs slow. The clock on Earth/Ship 1 does not. (Again, assuming my FTL warp drive in my JBIS paper where, when FTL is engaged, the rate of the clock on the ship does not change rate relative to it's rate before FTL was engaged.)
I will try repeating this again:
The paradox does not care how much time passes for the people on the ship.
All that matters are how events transpire in the initial frame of ship 1 and the initial frame of ship 2. If you need to, just imagine someone co-travelling with these ships who is left behind by an FTL jump.
All statements related to the amount of time passing on the ship during FTL are irrelevant.
If you mention the amount of time passing on the ship during FTL again, other than to acknowledge these statements, I will just repeat this, because if you do not get this, you haven't understood anything I have said.
At the time Ship 1 reaches Ship 2, what I mean by "instantaneous" is, that if the FTL trip took 0 time for Ship 1, it would leave Earth at Year 5 and arrive at Ship 2's location, when Ship 2's clock is at Year 4. Likewise, when Ship 2 sees Ship 1 arrive, they instantaneously travel back to Earth. The clock on Earth is at Year 5, the clock on Ship 2 is still Year 4. Neither Ship 1 nor Ship 2 took any time to travel the 3 light years between them, but the clocks do not agree. There is no paradox, we can't go any faster than "instantaneous", and we can never go backwards in time in either frame.
You are defining instantaneous differently for the 2 ships. In the ship 2 frame, the Earth clock is at Year 3.2, when the ship 2 is at Year 4.
IMO, this model makes perfect sense, there are no paradoxes and it is consistent with General Relativity. Symmetry is not required, it's the "special" case, and because of it's specialness, SR leads to paradoxes. The principle that all inertial frames are equal is an "assumption" of the the theory of SR. It is what makes SR Special, but it's not realistic.
General relativity introduces more ways to get paradoxes, and reduces to special relativity in the relevant cases we are discussing (The GR paradoxes are all currently excluded from implementation by things like event horizons and the need for exotic (negative mass) matter). The assumption that all inertial reference frames are equal is also part of general relativity. It is a very realistic assumption because it has been experimentally observed to be true.
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As for a consistent way to implement FTL, I have not done the math to fully work this out yet, but here are my thoughts:
I believe it is correct that it can be done by picking one reference frame to be the ultimate arbiter of "forward in time" for the entire universe. Every experiment we have done says that this is not out universe, but restricting it so that no FTL drive can move backwards in time in the preferred frame should prevent paradoxes. This also contradicts the most basic principle in relativity, so I am not sure exactly what else would have to change in physics, probably things like the speed of light would only truly be constant in one frame (or maybe the concept of aether would need to be brought back), also relativistic effects if they still exist at all would probably have to be tied to velocity in the special frame. If you are just writing interstellar hard sci-fi, picking a preferred frame for FTL should be good enough. (If you are going to pick a special frame, the center of the galaxy is the closest object you could tie it to that would seem believable, really it should just be some arbitrary frame that even our galaxy has some velocity relative to.)
If we can demonstrate that it requires messing with the speed of light universally, then we have killed it. We will have to keep thinking about that.
Though in science fiction, that could be one solution:
SCIENTIST: I have just created AI!
AI: Urp.
AI: FTL is possible.
SCIENTIST: No it is n...
AI: Hehehe.
SCIENTIST: Did you just consume the solar system, build a matrioshka brain, and then emulate me in some sort of.. of video game??
AI: No.
AI: Would I lie to you? :)
Rather than the center of the galaxy, how about the CMB reference frame?
https://en.wikipedia.org/wiki/Cosmic_microwave_background#CMBR_dipole_anisotropy
"From the CMB data it is seen that the Local Group (the galaxy group that includes the Milky Way galaxy) appears to be moving at 627±22 km/s relative to the reference frame of the CMB (also called the CMB rest frame, or the frame of reference in which there is no motion through the CMB)"
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At the time Ship 1 reaches Ship 2, what I mean by "instantaneous" is, that if the FTL trip took 0 time for Ship 1, it would leave Earth at Year 5 and arrive at Ship 2's location, when Ship 2's clock is at Year 4. Likewise, when Ship 2 sees Ship 1 arrive, they instantaneously travel back to Earth. The clock on Earth is at Year 5, the clock on Ship 2 is still Year 4. Neither Ship 1 nor Ship 2 took any time to travel the 3 light years between them, but the clocks do not agree. There is no paradox, we can't go any faster than "instantaneous", and we can never go backwards in time in either frame.
You are defining instantaneous differently for the 2 ships.
Yes, that is correct, because the situation is not symmetrical.
In the ship 2 frame, the Earth clock is at Year 3.2, when the ship 2 is at Year 4.
... and that observation is incorrect, it is an illusion.
Can we agree that the symmetry is the cause of the paradox please?
I put forward that the paradox cannot happen, because the symmetrical scenario which results in a paradox is not physically possible within the confines of our galaxy, or local cluster.
I repeat...
IMO, this model makes perfect sense, there are no paradoxes and it is consistent with General Relativity. Symmetry is not required, it's the "special" case, and because of it's specialness, SR leads to paradoxes. The principle that all inertial frames are equal is an "assumption" of the the theory of SR. It is what makes SR Special, but it's not realistic.
General relativity introduces more ways to get paradoxes, and reduces to special relativity in the relevant cases we are discussing (The GR paradoxes are all currently excluded from implementation by things like event horizons and the need for exotic (negative mass) matter). The assumption that all inertial reference frames are equal is also part of general relativity. It is a very realistic assumption because it has been experimentally observed to be true.
GR is perfectly consistent with inertial reference frames having different rates of time passage. By insisting on having symmetry, what you are saying is that when Ship 2 accelerates away from earth, (not FTL) to 0.6c, it's clock rate is unaffected. It is still the same as it was on Earth. As such, you expect the situation to be symmetrical and therefore you end up with a paradox. I'm saying, the clock on the ship really is slower than the clock on Earth, not vis-versa. It is not symmetrical, and it can't be symmetrical within our galaxy.
Anyone: Please give a "realistic" example of how Ship 2 came to be moving at 0.6c relative to the Earth where, it did not previously accelerate to that speed. Given that there have been no observations of stars or planets in our galaxy that are moving more than a little over 100 km/s. Nowhere near 0.6c, and there are no worlds orbiting stars or BH's at 0.6c either. The fastest stable orbit around a BH is .5c and it oscillates relative to Earth. So the situation in which Ship 2 has always been moving 0.6c relative to the Earth is unrealistic (if not impossible). Therefore, the symmetry required to cause a paradox, does not exist.
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At the time Ship 1 reaches Ship 2, what I mean by "instantaneous" is, that if the FTL trip took 0 time for Ship 1, it would leave Earth at Year 5 and arrive at Ship 2's location, when Ship 2's clock is at Year 4. Likewise, when Ship 2 sees Ship 1 arrive, they instantaneously travel back to Earth. The clock on Earth is at Year 5, the clock on Ship 2 is still Year 4. Neither Ship 1 nor Ship 2 took any time to travel the 3 light years between them, but the clocks do not agree. There is no paradox, we can't go any faster than "instantaneous", and we can never go backwards in time in either frame.
You are defining instantaneous differently for the 2 ships.
Yes, that is correct, because the situation is not symmetrical.
In the ship 2 frame, the Earth clock is at Year 3.2, when the ship 2 is at Year 4.
... and that observation is incorrect, it is an illusion.
Can we agree that the symmetry is the cause of the paradox please?
I put forward that the paradox cannot happen, because the symmetrical scenario which results in a paradox is not physically possible within the confines of our galaxy, or local cluster.
I repeat...
IMO, this model makes perfect sense, there are no paradoxes and it is consistent with General Relativity. Symmetry is not required, it's the "special" case, and because of it's specialness, SR leads to paradoxes. The principle that all inertial frames are equal is an "assumption" of the the theory of SR. It is what makes SR Special, but it's not realistic.
General relativity introduces more ways to get paradoxes, and reduces to special relativity in the relevant cases we are discussing (The GR paradoxes are all currently excluded from implementation by things like event horizons and the need for exotic (negative mass) matter). The assumption that all inertial reference frames are equal is also part of general relativity. It is a very realistic assumption because it has been experimentally observed to be true.
GR is perfectly consistent with inertial reference frames having different rates of time passage. By insisting on having symmetry, what you are saying is that when Ship 2 accelerates away from earth, (not FTL) to 0.6c, it's clock rate is unaffected. It is still the same as it was on Earth. As such, you expect the situation to be symmetrical and therefore you end up with a paradox. I'm saying, the clock on the ship really is slower than the clock on Earth, not vis-versa. It is not symmetrical, and it can't be symmetrical within our galaxy.
Anyone: Please give a "realistic" example of how Ship 2 came to be moving at 0.6c relative to the Earth where, it did not previously accelerate to that speed. Given that there have been no observations of stars or planets in our galaxy that are moving more than a little over 100 km/s. Nowhere near 0.6c, and there are no worlds orbiting stars or BH's at 0.6c either. The fastest stable orbit around a BH is .5c and it oscillates relative to Earth. So the situation in which Ship 2 has always been moving 0.6c relative to the Earth is unrealistic (if not impossible). Therefore, the symmetry required to cause a paradox, does not exist.
About the twin paradox and time moving slow along with length contraction via acceleration (velocity + time travel) velocity coming with acceleration.
When I was in class they had this old macintosh program where you could switch between two relative frames. The earth and a space ship. It had multiple clocks running so you could see synchronous/non-synch clocks. The earth frame saw the ship as length contracted and de-synched its clocks. This would be due to time travel. The tip of the space ship has time subtracted from it with its forward velocity while the back of the ship has less time subtracted from it. Essentially the earth observer sees the ship as traveling into the past which makes sense because the ship person will have less time pass.
So time in this case did slow for the ship but during acceleration is when the length contraction magic happens which allows time travel via the rotation of the time space axis on a light cone. The length contraction only happens to the ship and not the universe so the time travel is limited to the ship.
In the ship frame, if I remember correctly, both effects happened as well. Time slowed down for the universe but during acceleration, length contraction was induced by your change in velocity. Time being added more the further away means that regardless of the universe time slowing down your forward progression (through time travel - length contraction) advances you more rapidly through the universes future than the effects of slowed time. I think the reason the clock still passes more slowly for the space outside the ship is because of the constancy of the speed of light. The same reason for the slow clock for those observing the contracted ship from earth.
It seems to describe their immediate local frame. Locally this keeps the speed of light constant but non-locally light from the short objects frame does seem to have light moving slowly compared to our space. Us not directly observing their slow light. Maybe we only see the translation between frames via slowed osculation in the light, or red-shifting via slowed time + moving away or towards effects.
As space outside contracts time must slow for the speed of light to remain c or dx/dt in the two frames.
This time travel (length contraction) via acceleration being limited to forward velocity limits us to traveling into the future and somewhat clarifies the twin paradox.
The math for the gradient in time over space for a moving observer is in this video at 2:43 https://www.youtube.com/watch?v=0iJZ_QGMLD0
Edited: dt=gamma(ti-v*dx/c^2) they forgot c^2 at the end of the equation in the video.
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At the time Ship 1 reaches Ship 2, what I mean by "instantaneous" is, that if the FTL trip took 0 time for Ship 1, it would leave Earth at Year 5 and arrive at Ship 2's location, when Ship 2's clock is at Year 4. Likewise, when Ship 2 sees Ship 1 arrive, they instantaneously travel back to Earth. The clock on Earth is at Year 5, the clock on Ship 2 is still Year 4. Neither Ship 1 nor Ship 2 took any time to travel the 3 light years between them, but the clocks do not agree. There is no paradox, we can't go any faster than "instantaneous", and we can never go backwards in time in either frame.
You are defining instantaneous differently for the 2 ships.
Yes, that is correct, because the situation is not symmetrical.
In the ship 2 frame, the Earth clock is at Year 3.2, when the ship 2 is at Year 4.
... and that observation is incorrect, it is an illusion.
No, it is not an illusion.
Can we agree that the symmetry is the cause of the paradox please?
Depends, we first would have to agree on the meaning of the word "symmetry."
You keep acting as if a spacecraft travelling at 0.7 c from some distant galaxy that has a high relative velocity to Earth would be fundamentally different from a spaceship that accelerated from Earth to the same speed. You however cannot name a single thing that is physically different between them (hint: there is no difference).
When you stop trying to simultaneously claim "no reference frame is special" and "some reference frames are special" this conversation might start getting somewhere.
I put forward that the paradox cannot happen, because the symmetrical scenario which results in a paradox is not physically possible within the confines of our galaxy, or local cluster.
Go back a couple posts where I asked you to do the math on (nearly) instantaneous travel, and frames separated by Earth's orbital velocity of 30km/s assuming a 10 light year jump.
GR is perfectly consistent with inertial reference frames having different rates of time passage. By insisting on having symmetry, what you are saying is that when Ship 2 accelerates away from earth, (not FTL) to 0.6c, it's clock rate is unaffected.
Where in the world did you get that contradictory idea?
Insisting on symmetry, meaning "all reference frames are equivalent" and therefore "the speed of light is the same in all reference frames" requires that Ship 2's clock rate runs slow as it approaches c. It also means that in the ship 2 inertial frame, it is ship 1's clock that runs slow.
Anyone: Please give a "realistic" example of how Ship 2 came to be moving at 0.6c relative to the Earth where, it did not previously accelerate to that speed.
Again, what is the difference whether it had undergone acceleration in the past? How can you tell that ship 2 didn't come from atoms that had been ejected from a distant galaxy? What is the magical "rest frame" that it originated from? What do you mean by the word always?
The whole point of these questions is for you to recognize the absurdity of your claim that as I said earlier in this post:
You keep acting as if a spacecraft travelling at 0.7 c from some distant galaxy that has a high relative velocity to Earth would be fundamentally different from a spaceship that accelerated from Earth to the same speed.
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At the time Ship 1 reaches Ship 2, what I mean by "instantaneous" is, that if the FTL trip took 0 time for Ship 1, it would leave Earth at Year 5 and arrive at Ship 2's location, when Ship 2's clock is at Year 4. Likewise, when Ship 2 sees Ship 1 arrive, they instantaneously travel back to Earth. The clock on Earth is at Year 5, the clock on Ship 2 is still Year 4. Neither Ship 1 nor Ship 2 took any time to travel the 3 light years between them, but the clocks do not agree. There is no paradox, we can't go any faster than "instantaneous", and we can never go backwards in time in either frame.
You are defining instantaneous differently for the 2 ships.
Yes, that is correct, because the situation is not symmetrical.
In the ship 2 frame, the Earth clock is at Year 3.2, when the ship 2 is at Year 4.
... and that observation is incorrect, it is an illusion.
No, it is not an illusion.
:o Okay then, back to the Twin Paradox. The twin on Earth calculates his brother traveling at 0.6c will age 8 years, the traveling twin calculates that his brother at home will age 6.4 years. One is right, the other is wrong. It's not symmetrical, their calculations are not even the same. The one who gets it wrong sees an illusion, because when he gets home he finds that his brother aged 10 years, not 6.4 years. "His" clock rate was slow, his brother's on Earth was not. Again, the rates are not physically symmetrical, so what he measures based on his slow clock is wrong.
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:o Okay then, back to the Twin Paradox. The twin on Earth calculates his brother traveling at 0.6c will age 8 years, the traveling twin calculates that his brother at home will age 6.4 years. One is right, the other is wrong. It's not symmetrical, their calculations are not even the same. The one who gets it wrong sees an illusion, because when he gets home he finds that his brother aged 10 years, not 6.4 years. "His" clock rate was slow, his brother's on Earth was not. Again, the rates are not physically symmetrical, so what he measures based on his slow clock is wrong.
An observer in the earth frame sees the traveler's clock as slow both outbound and inbound.
An observer in the outbound frame sees the Earth clock as slow the whole time, the outbound traveler's clock as normal speed, but slowing down greatly after turning around, to the net effect of being slower on average.
An observer in the inbound frame sees the Earth clock as slow, the outbound clock as really slow, and the inbound clock as normal.
Everyone agrees that the travelling twin experienced less time passing, and no one gets it wrong. The only "asymmetry" is that one twin accelerated half way through and the other didn't. The effects the travelling twin experienced as they accelerated to turn around include a lot of everyone else's clocks changing speed, or even "rewinding" to match his new frame. The lesson is to stick to inertial frames when doing the calculations. Some of your mistakes that are leading you to claim "no paradox" in time travel causing situations seem to be related to you not understanding this lesson.
Now can you get to the rest of my post where I pointed out some of the ways you directly are contradicting yourself?
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:o Okay then, back to the Twin Paradox. The twin on Earth calculates his brother traveling at 0.6c will age 8 years, the traveling twin calculates that his brother at home will age 6.4 years. One is right, the other is wrong. It's not symmetrical, their calculations are not even the same. The one who gets it wrong sees an illusion, because when he gets home he finds that his brother aged 10 years, not 6.4 years. "His" clock rate was slow, his brother's on Earth was not. Again, the rates are not physically symmetrical, so what he measures based on his slow clock is wrong.
An observer in the earth frame sees the traveler's clock as slow both outbound and inbound.
An observer in the outbound frame sees the Earth clock as slow the whole time, the outbound traveler's clock as normal speed, but slowing down greatly after turning around, to the net effect of being slower on average.
An observer in the inbound frame sees the Earth clock as slow, the outbound clock as really slow, and the inbound clock as normal.
Everyone agrees that the travelling twin experienced less time passing, and no one gets it wrong. The only "asymmetry" is that one twin accelerated half way through and the other didn't. The effects the travelling twin experienced as they accelerated to turn around include a lot of everyone else's clocks changing speed, or even "rewinding" to match his new frame. The lesson is to stick to inertial frames when doing the calculations. Some of your mistakes that are leading you to claim "no paradox" in time travel causing situations seem to be related to you not understanding this lesson.
Now can you get to the rest of my post where I pointed out some of the ways you directly are contradicting yourself?
I'm not trying to sound arrogant or be argumentative, but from my perspective you are the one who is making unrealistic assumptions and contradicting yourself. So let's please try to avoid statements like that. I'll get to the rest of your email, once we agree on what the Twin Paradox actually teaches us. You keep missing the point and I'm just going to have to get better at explaining it, until you get it. This is actually something that should be in my paper, so I appreciate this discussion immensely. Coming to a consensus here will prevent errors there.
In your above statements, you are perfectly fine with the asymmetry where, the twin who travels has to accelerate to turn around and head back toward earth. But you ignore the acceleration that started the trip in the first place, as did the video that Dustin posted.
What I am trying to convey is, when the Twin (ship 2) left Earth, it accelerated to 0.6c using a Non-FTL drive. This acceleration phase resolves the paradox as follows;
1. During this first acceleration phase, Earth "seems" to lose 1.8 years as ship 2 accelerates to 0.6c away from Earth. But the Earth didn't go back in time, "his" space axis rotated CCW because he's moving away from it.
2. When the twin slows down to begin his turn back toward Earth his space axis rotates CW, momentarily re-aligns with the Earth frame, and the 1.8 years that was lost is restored. His axis at year 4 on his clock is simultaneously re-aligned with year 5 on the Earth clock. An FTL jump (instantaneous for him) will take him back to Earth at year 5, not year 3.2.
[edit: Regardless of what type of drive it is, sub-light or FTL, in order to go back to Earth, his space axis must swing back CW, through this re-alingment, until the twin/ship 2 is moving toward Earth at whatever speed and never goes backward in time.]
3. He continues to accelerates back toward Earth and Earth quickly ages another 1.8 years until reaching -0.6c.
4. He then decelerates when he arrives back home and his axis re-aligns with the Earth's frame, where his clock is at year 8 and the Earth clock is at year 10.
The FTL paradox such that ship 2 could go backwards along its space axis to Earth at year 3.2 rather than year 5, is like saying when the Twin returns to Earth, his brother only aged 6.4 years and not 10 years. It's the wrong answer.
By ignoring the first acceleration phase and assuming that the two frames are interchangeable, it leads to a paradox. By including all 3 acceleration phases, the paradox is resolved.
A distant galaxy moving away from us at 0.6c since the big bang is different. I would assume that the Milky way and that distant galaxy were both created and accelerated equally at the same time, by the same force (i.e, the Big Bang). Whereas, ship 2 and the Earth were not both accelerated at the same time by the same force. Only the ship was accelerated. That's the asymmetry. IMO, there is no way to have a symmetrical situation within our galaxy. There is ALWAYS an initial acceleration phase and ignoring it will fool you into seeing a paradox where there is none.
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:o Okay then, back to the Twin Paradox. The twin on Earth calculates his brother traveling at 0.6c will age 8 years, the traveling twin calculates that his brother at home will age 6.4 years. One is right, the other is wrong. It's not symmetrical, their calculations are not even the same. The one who gets it wrong sees an illusion, because when he gets home he finds that his brother aged 10 years, not 6.4 years. "His" clock rate was slow, his brother's on Earth was not. Again, the rates are not physically symmetrical, so what he measures based on his slow clock is wrong.
An observer in the earth frame sees the traveler's clock as slow both outbound and inbound.
An observer in the outbound frame sees the Earth clock as slow the whole time, the outbound traveler's clock as normal speed, but slowing down greatly after turning around, to the net effect of being slower on average.
An observer in the inbound frame sees the Earth clock as slow, the outbound clock as really slow, and the inbound clock as normal.
Everyone agrees that the travelling twin experienced less time passing, and no one gets it wrong. The only "asymmetry" is that one twin accelerated half way through and the other didn't. The effects the travelling twin experienced as they accelerated to turn around include a lot of everyone else's clocks changing speed, or even "rewinding" to match his new frame. The lesson is to stick to inertial frames when doing the calculations. Some of your mistakes that are leading you to claim "no paradox" in time travel causing situations seem to be related to you not understanding this lesson.
Now can you get to the rest of my post where I pointed out some of the ways you directly are contradicting yourself?
I'm not trying to sound arrogant or be argumentative, but from my perspective you are the one who is making unrealistic assumptions and contradicting yourself. So let's please try to avoid statements like that. I'll get to the rest of your email, once we agree on what the Twin Paradox actually teaches us. You keep missing the point and I'm just going to have to get better at explaining it, until you get it. This is actually something that should be in my paper, so I appreciate this discussion immensely. Coming to a consensus here will prevent errors there.
In your above statements, you are perfectly fine with the asymmetry where, the twin who travels has to accelerate to turn around and head back toward earth. But you ignore the acceleration that started the trip in the first place, as did the video that Dustin posted.
What I am trying to convey is, when the Twin (ship 2) left Earth, it accelerated to 0.6c using a Non-FTL drive. This acceleration phase resolves the paradox as follows;
1. During this first acceleration phase, Earth "seems" to lose 1.8 years as ship 2 accelerates to 0.6c away from Earth. But the Earth didn't go back in time, "his" space axis rotated CCW because he's moving away from it.
2. When the twin slows down to begin his turn back toward Earth his space axis rotates CW, momentarily re-aligns with the Earth frame, and the 1.8 years that was lost is restored. His axis at year 4 on his clock is simultaneously re-aligned with year 5 on the Earth clock. An FTL jump (instantaneous for him) will take him back to Earth at year 5, not year 3.2.
[edit: Regardless of what type of drive it is, sub-light or FTL, in order to go back to Earth, his space axis must swing back CW, through this re-alingment, until the twin/ship 2 is moving toward Earth at whatever speed and never goes backward in time.]
3. He continues to accelerates back toward Earth and Earth quickly ages another 1.8 years until reaching -0.6c.
4. He then decelerates when he arrives back home and his axis re-aligns with the Earth's frame, where his clock is at year 8 and the Earth clock is at year 10.
The FTL paradox such that ship 2 could go backwards along its space axis to Earth at year 3.2 rather than year 5, is like saying when the Twin returns to Earth, his brother only aged 6.4 years and not 10 years. It's the wrong answer.
By ignoring the first acceleration phase and assuming that the two frames are interchangeable, it leads to a paradox. By including all 3 acceleration phases, the paradox is resolved.
A distant galaxy moving away from us at 0.6c since the big bang is different. I would assume that the Milky way and that distant galaxy were both created and accelerated equally at the same time, by the same force (i.e, the Big Bang). Whereas, ship 2 and the Earth were not both accelerated at the same time by the same force. Only the ship was accelerated. That's the asymmetry. IMO, there is no way to have a symmetrical situation within our galaxy. There is ALWAYS an initial acceleration phase and ignoring it will fool you into seeing a paradox where there is none.
Your right they do start off with the ship at full speed at 1:57. That or its an instantaneous or violent acceleration seemingly instantly tilting the space axis so the ship is distorted in time. From the ship perspective space is distorted in time (future in front). (This FTL - I'm reminded of the Portal game and droping through 2 portals while being accelerated by gravity = impossible). With the space axis always tilted up in the direction the ship travels, without FTL and its odd seeming momentum violation, the ship's only alternative it to travel into the future. Behind the ship is the past. Technically if the ships FTL distance is not limited it could jump as far into the past as it wants which is absurd. If distance is an obstacle for the FTL all the ship has to do is approach the c limit and eventually all the past is still reachable by jumping backwards.
Here is a paradox. A ship is falling into a black hole. Just before hitting the event horizon they jump into the past but preserving their velocity. They fall again and keep jumping back till they themselves become a black hole. :o
Regardless - if FTL exists it probably doesn't exist in the sense of instant teleportation, which causes energy violations even in a classical sense.
As for the FTL signal, is that the same sense as a portal? Are we talking a photon that gets teleported across a distance? If so the same energy violation could be an issue. A satellite could FTL/portal an incoming signal away. The signal undergoes gravitational acceleration and gets sent out again to repeat its acceleration.
vast distances a problem? Put it in an extreme vacuum chamber and only do lots of short portal jumps.
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I'm not trying to sound arrogant or be argumentative, but from my perspective you are the one who is making unrealistic assumptions and contradicting yourself. So let's please try to avoid statements like that. I'll get to the rest of your email, once we agree on what the Twin Paradox actually teaches us. You keep missing the point and I'm just going to have to get better at explaining it, until you get it. This is actually something that should be in my paper, so I appreciate this discussion immensely. Coming to a consensus here will prevent errors there.
In your above statements, you are perfectly fine with the asymmetry where, the twin who travels has to accelerate to turn around and head back toward earth. But you ignore the acceleration that started the trip in the first place, as did the video that Dustin posted.
What I am trying to convey is, when the Twin (ship 2) left Earth, it accelerated to 0.6c using a Non-FTL drive. This acceleration phase resolves the paradox as follows;
...
Your right they do start off with the ship at full speed at 1:57. That or its an instantaneous or violent acceleration seemingly instantly tilting the space axis so the ship is distorted in time. From the ship perspective space is distorted in time (future in front). (This FTL - I'm reminded of the Portal game and droping through 2 portals while being accelerated by gravity = impossible). With the space axis always tilted up in the direction the ship travels, without FTL and its odd seeming momentum violation, the ship's only alternative it to travel into the future. Behind the ship is the past. Technically if the ships FTL distance is not limited it could jump as far into the past as it wants which is absurd. If distance is an obstacle for the FTL all the ship has to do is approach the c limit and eventually all the past is still reachable by jumping backwards.
Here is a paradox. A ship is falling into a black hole. Just before hitting the event horizon they jump into the past but preserving their velocity. They fall again and keep jumping back till they themselves become a black hole. :o
Regardless - if FTL exists it probably doesn't exist in the sense of instant teleportation, which causes energy violations even in a classical sense.
As for the FTL signal, is that the same sense as a portal? Are we talking a photon that gets teleported across a distance? If so the same energy violation could be an issue. A satellite could FTL/portal an incoming signal away. The signal undergoes gravitational acceleration and gets sent out again to repeat its acceleration.
vast distances a problem? Put it in an extreme vacuum chamber and only do lots of short portal jumps.
Correct, instantaneous teleportation would require infinite energy, even in my JBIS warp drive paper. It doesn't propose any way to send a signal FTL. I think it would probably require some sort of probe that would travel FTL to communicate, but who knows what will happen once the principles are understood.
IMO, the past no longer exists because it would violate conservation of energy. The same for the multiverse. The energy that makes up this moment "now" carries forward to the next moment, and on into the future, energy is conserved. If the past were still there, then every moment in time would have to be replicating that much energy, down to intervals the size of the Planck scale to appear "continuous". Where is all that energy coming from? Why would we allow our most important law of physics to be violated on a large scale? I'm sorry, but IMO, time travel into the past is never going to happen.
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Just in case that you think I am being arrogant here, please remember that my confidence in my position does not come from my assessment of my own intelligence, but from the fact that my position is shared by literally every physicist I have ever seen describe relativity, and every paper or textbook in the field that I have ever read.
I'll get to the rest of your email, once we agree on what the Twin Paradox actually teaches us.
I don't think we will ever be able to get there unless you resolve at least the most blatant of contradictory statements you have made. You have within the same paragraph both claimed that there are all inertial reference frames are equivalent, and that some inertial reference frames are special. Pick one.
At least we "agree" on one thing:
You keep missing the point and I'm just going to have to get better at explaining it, until you get it. This is actually something that should be in my paper, so I appreciate this discussion immensely. Coming to a consensus here will prevent errors there.
This is something I would say to you. Explaining special relativity to you greatly helps me get better at explaining relativity.
In your above statements, you are perfectly fine with the asymmetry where, the twin who travels has to accelerate to turn around and head back toward earth. But you ignore the acceleration that started the trip in the first place, as did the video that Dustin posted.
Here is the trick with that one. The initial/final acceleration takes place when both twins are in the same location, so the travelling twin doesn't see the other twin's clock fast-forward or rewind during the (implicitly assumed) brief acceleration. If the other twin was the one that accelerated at the start and end, or if the they had both accelerated some amount, nothing would change about the results.
As a result, your explanation where the initial/final acceleration matters is simply inconsistent. For one thing just after the acceleration completed they could send messages to each other with fairly short delays and see that 1.8 years hadn't passed for the non-accelerated twin. Second, the 1.8 years that you claim happen during the initial acceleration require that he travel 5 years before turning around. If he decides to turn around sooner or later, your explanation breaks down.
A distant galaxy moving away from us at 0.6c since the big bang is different. I would assume that the Milky way and that distant galaxy were both created and accelerated equally at the same time, by the same force (i.e, the Big Bang). Whereas, ship 2 and the Earth were not both accelerated at the same time by the same force.
But what is different? Given 2 objects, one that came from that other galaxy and one that came from ours, and accelerated to match speed how could you tell which was which?
IMO, there is no way to have a symmetrical situation within our galaxy.
Rather than opinion, why don't you do math and work out the example I suggested using only Earth orbital velocity.
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IMO, the past no longer exists because it would violate conservation of energy. The same for the multiverse. The energy that makes up this moment "now" carries forward to the next moment, and on into the future, energy is conserved. If the past were still there, then every moment in time would have to be replicating that much energy, down to intervals the size of the Planck scale to appear "continuous". Where is all that energy coming from? Why would we allow our most important law of physics to be violated on a large scale? I'm sorry, but IMO, time travel into the past is never going to happen.
That's one the reasons why people say FTL travel is impossible. Under General Relativity FTL equals time travel.
If FTL travel is possible, we don't have the math or understanding of the universe to figure it out. Maybe after unifying GR and Quantum Theory.
The issue with the twin paradox is that we're trying to describe it under Special Relativity and that does not include accelerating frames of reference. It's above my pay grade, but I bet if we did the math under GR there would not be a problem since we can include the acceleration of the spaceship.
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In general, is this a debate over whether Alcubierre warp bubbles or wormholes could ever exist, or whether literal FTT travel through space cannot exist? Thanks.
Also, regarding the twin paradox, if two ships discover each other at some relative velocity, and each is ignorant of the history of the other and themselves, can it be established how they age relative to each other with no external references. It there enough information? Thanks.
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Just in case that you think I am being arrogant here, please remember that my confidence in my position does not come from my assessment of my own intelligence, but from the fact that my position is shared by literally every physicist I have ever seen describe relativity, and every paper or textbook in the field that I have ever read.
I know this. I've been trying to teach people this alternative for a long time. Eventually, some people do get it, but others just want to argue. If we work together, we can make it so that FTL is possible and the paradoxes are not. That's my goal. Is it yours?
I'll get to the rest of your email, once we agree on what the Twin Paradox actually teaches us.
I don't think we will ever be able to get there unless you resolve at least the most blatant of contradictory statements you have made. You have within the same paragraph both claimed that there are all inertial reference frames are equivalent, and that some inertial reference frames are special. Pick one.
I am trying to avoid a full blown lecture on QED and the Polarizable Vacuum theory of General Relativity. The simplest way to explain it is with Math. So;
ds2 = K*dx2 - (1/K)*c2dt2
Where, K = g11 = -1/g00 for simplicity.
If K = 1, this is a Minkowski (flat) space-time. We can draw a space-time diagram, where c=1, and the speed of light is represented by a light-cone with a 45-deg slope.
What happens when K is not 1?
When K > 1, the light-cone gets narrower and c < 1.
When K < 1, the light-cone gets wider and c > 1.
You can prove this by setting ds = 0, and solving for the coordinate speed of light;
dx/dt = c/K
As long as K is a "constant", then it is an inertial reference frame. A "scaled" version of space-time. The scaling must be done correctly using dimensional analysis,(M,L,T) but it is fairly easy. Simply replace the dimensional values as follows. The value where K=1 will be signified with a subscript, "0".
Mass M = M0*K3/2
Length L = L0/√K
Time T = T0*√K
In doing so, we have an infinite number of inertial reference frames, each defined by a different refractive index, K. When we are immersed in this reference frame, rulers and clocks are always normalized so that the local value of c = 1. The relative value of K can only be measured by a distant observer. Typically, we take the distant observer to be far from all matter and we define this "special" case as K=1, and then any gravitational fields have values of K > 1. Any FTL field will have a value of K < 1.
K doesn't have to be a constant, it can be a variable of the coordinates, such as the Schwarzschild metric. It is ALWAYS composed of the metric coefficients from GR and represents the gravitational field. The variable refractive index is the result of a variable Damping Factor which acts on the quantum harmonic oscillators that compose matter. So where K > 1, i.e, in a gravity well, the damping factor is larger. Far from matter, we expect the damping factor to go to zero, where K = 1 is defined for the distant observer.
Motion relative to the local baseline gravitational field also increases the damping factor, so gravitational time dilation and length contraction, and the effects of motion through the field, are both caused by increased damping. In that regard, motion relative to the "local baseline gravitational field" and the renormalization of K=1 locally, is what gives us Special Relativity. But non-locally, inertial reference frames with different values of K have different scaling. It is a Conformal theory of gravity.
In your above statements, you are perfectly fine with the asymmetry where, the twin who travels has to accelerate to turn around and head back toward earth. But you ignore the acceleration that started the trip in the first place, as did the video that Dustin posted.
Here is the trick with that one. The initial/final acceleration takes place when both twins are in the same location, so the travelling twin doesn't see the other twin's clock fast-forward or rewind during the (implicitly assumed) brief acceleration. If the other twin was the one that accelerated at the start and end, or if the they had both accelerated some amount, nothing would change about the results.
As a result, your explanation where the initial/final acceleration matters is simply inconsistent. For one thing just after the acceleration completed they could send messages to each other with fairly short delays and see that 1.8 years hadn't passed for the non-accelerated twin. Second, the 1.8 years that you claim happen during the initial acceleration require that he travel 5 years before turning around. If he decides to turn around sooner or later, your explanation breaks down.
You got me on that one. I didn't think through my wording very well, but I understood that the 1.8 years was referring to when he was 4-years down the road. My point was, when he is moving "away" his space-axis rotates CCW, and when he's moving toward Earth, his space-axis is rotated CW, and it is always "his space-axis" that is rotating, not the Earth's, and we should acknowledge that his axis rotates at every acceleration phase, including the first one where he leaves Earth. Even with FTL, there is no way I can think of to approach something and have the axis tilted as if moving away from it.
A distant galaxy moving away from us at 0.6c since the big bang is different. I would assume that the Milky way and that distant galaxy were both created and accelerated equally at the same time, by the same force (i.e, the Big Bang). Whereas, ship 2 and the Earth were not both accelerated at the same time by the same force.
But what is different? Given 2 objects, one that came from that other galaxy and one that came from ours, and accelerated to match speed how could you tell which was which?
The relative baseline is different, but I gave this some more thought and you're right in that it doesn't matter. My conjecture was that the big bang was identical to launching 2 ships from Earth in opposite directions, but launching 1 ship was different. Launching 2 ships does create a symmetrical situation. However, the Earth's clock rate is still faster than either ship. If both ships were at +/- 0.6c relative to Earth, and both ships FTL jump back to Earth after 4 years, the clock on Earth will be at 5 years, and both ships would be at 4 years. If the one ship jumped to the other, both ships would be at 4 years, because they have the same relative change in damping, relative to the field around the Earth they were launched from.
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In general, is this a debate over whether Alcubierre warp bubbles or wormholes could ever exist, or whether literal FTT travel through space cannot exist? Thanks.
Any of the above. They all would allow for time travel, unless there was some explicit mechanism that would prevent any of the causality breaking scenarios, such as one wormhole disrupting the possibility of creating a parallel wormhole that has some relative velocity. As I understand it, the OP for this thread was basically asking for what mechanisms could do this.
Also, regarding the twin paradox, if two ships discover each other at some relative velocity, and each is ignorant of the history of the other and themselves, can it be established how they age relative to each other with no external references. It there enough information? Thanks.
Yes, but they would both see the other as aging slower. This is because of the relativity of simultaneity, "now" is reference frame dependent. To get them to agree on their relative age, you have to have them meet back up, so there is an "event" that they are both present for, so they have to agree on each other's current age when they pass by each other. If they met back up, the relative age would depend on which turned around to meet up with the other.
I would be curious as to WarpTech's answer to this, as he seems to think objects somehow store the history of the accelerations they have undergone and that their dynamic behavior is somehow different as a result.
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In general, is this a debate over whether Alcubierre warp bubbles or wormholes could ever exist, or whether literal FTT travel through space cannot exist? Thanks.
Also, regarding the twin paradox, if two ships discover each other at some relative velocity, and each is ignorant of the history of the other and themselves, can it be established how they age relative to each other with no external references. It there enough information? Thanks.
The debate is whether FTL requires time travel. I say, FTL is possible, time travel is not and there are no paradoxes when we understand GR and SR in the correct context. However, this context is not in the text books so I'm fighting an uphill battle to teach people how to re-interpret what they think they already know.
To answer your question, they would need to be in communication, and preferably have a local interaction so that they can synchronize a pair of clocks, in the same place at the same time. Then go merrily on their way.
Edit: I agree with @meberbs, they would need to meet back up a 2nd time to compare clocks.
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In general, is this a debate over whether Alcubierre warp bubbles or wormholes could ever exist, or whether literal FTT travel through space cannot exist? Thanks.
Any of the above. They all would allow for time travel, unless there was some explicit mechanism that would prevent any of the causality breaking scenarios, such as one wormhole disrupting the possibility of creating a parallel wormhole that has some relative velocity. As I understand it, the OP for this thread was basically asking for what mechanisms could do this.
Also, regarding the twin paradox, if two ships discover each other at some relative velocity, and each is ignorant of the history of the other and themselves, can it be established how they age relative to each other with no external references. It there enough information? Thanks.
Yes, but they would both see the other as aging slower. This is because of the relativity of simultaneity, "now" is reference frame dependent. To get them to agree on their relative age, you have to have them meet back up, so there is an "event" that they are both present for, so they have to agree on each other's current age when they pass by each other. If they met back up, the relative age would depend on which turned around to meet up with the other.
I would be curious as to WarpTech's answer to this, as he seems to think objects somehow store the history of the accelerations they have undergone and that their dynamic behavior is somehow different as a result.
Thanks. I'm absorbing your answer....I may have to dig out my copy of Wheeler and Taylor.
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In general, is this a debate over whether Alcubierre warp bubbles or wormholes could ever exist, or whether literal FTT travel through space cannot exist? Thanks.
Also, regarding the twin paradox, if two ships discover each other at some relative velocity, and each is ignorant of the history of the other and themselves, can it be established how they age relative to each other with no external references. It there enough information? Thanks.
The debate is whether FTL requires time travel. I say, FTL is possible, time travel is not and there are no paradoxes when we understand GR and SR in the correct context. However, this context is not in the text books so I'm fighting an uphill battle to teach people how to re-interpret what they think they already know.
To answer your question, they would need to be in communication, and preferably have a local interaction so that they can synchronize a pair of clocks, in the same place at the same time. Then go merrily on their way.
Edit: I agree with @meberbs, they would need to meet back up a 2nd time to compare clocks.
Thanks!
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In general, is this a debate over whether Alcubierre warp bubbles or wormholes could ever exist, or whether literal FTT travel through space cannot exist? Thanks.
Hi Bob012345,
When I started this thread, the goal was to find a definition of FTL that avoids paradox. It is not about the theory of any particular method or whether it actually exists, just if you can describe what you are claiming it would allow you to do.
Another way of looking at it could be "Guilt-free FTL rules for HardSF writers". You don't need to explain the machine. It Glows. It makes noises. Things spin. But you do have to explain the characters. Who can understand a universe full of characters living in a universe where you could create a paradox with a few simple steps, and no one does it, and no one talks about it?
I started this thread thinking we could demonstrate a paradox with a single FTL flight. At the moment we have a claim that you can avoid all paradoxes by limiting FTL to a special frame, such as the CMB rest frame. I don't think anyone has been able to directly discredit that yet.. though we don't necessarily like it :-)
Im sort of waiting for some wizzes at relativity to come along and pull the rug out from under that one with a specific example that shows it still produces paradoxes. That is where we are at the moment.
One really weird thing about a universe like that, is that travelling in one particular direction you would be travelling into the past, just not far enough to get back in time to cause paradox. So I guess your friend could jump a lightyear to the left and you could see them immediately jump out of their ship and start waving to you, because all this happened a year ago over there, and the light has been travelling towards you all that time!
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So you're trying to find rules obeying relativity to do something that relativity absolutely prohibits?
Sounds a bit like atheists trying to justify themselves through theology.
Seems the more honest thing to do is to acknowledge that relativity totally prohibits FTL and either throw relativity out completely (atheist) or throw FTL out completely (church lady).
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At the moment we have a claim that you can avoid all paradoxes by limiting FTL to a special frame, such as the CMB rest frame. I don't think anyone has been able to directly discredit that yet.. though we don't necessarily like it :-)
Im sort of waiting for some wizzes at relativity to come along and pull the rug out from under that one with a specific example that shows it still produces paradoxes. That is where we are at the moment.
Having suggested the existence of a special frame to begin with, I feel I should clarify. If there is such a thing as a special frame that you limit FTL to, the entire theory of relativity collapses, because this directly contradicts its most fundamental assumption. I have no idea what, if anything, you could replace it with unless you want to ignore untold numbers of experimental results.
So you're trying to find rules obeying relativity to do something that relativity absolutely prohibits?
Which is why the best solution I could come up with is to break the one fundamental assumption underlying relativity.
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Having suggested the existence of a special frame to begin with, I feel I should clarify. If there is such a thing as a special frame that you limit FTL to, the entire theory of relativity collapses, because this directly contradicts its most fundamental assumption. I have no idea what, if anything, you could replace it with unless you want to ignore untold numbers of experimental results.
So you're trying to find rules obeying relativity to do something that relativity absolutely prohibits?
Which is why the best solution I could come up with is to break the one fundamental assumption underlying relativity.
Im not sure I am understanding you. We are probably saying the same thing and just wording it differently. To be clear, you are not talking about changing the universe in a way that invalidates current experiments, correct? All those experiments have to still deliver the same outcomes.
Breaking the assumption is fine, If I know what you mean. Relativity can be perfect like a sphere without being a statement that there is no such thing as a cube, or that you won't suddenly come across a cube embedded in your sphere.
This is why Im only concerned with paradoxes, or solutions that require current experiments to suddenly deliver different outcomes, and Im still not convinced there is not still a nasty paradox hidden in there somewhere. Im still expecting someone to pull the rug out from under this with an example that shows it is just as nonsensical as general FTL.
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At the moment we have a claim that you can avoid all paradoxes by limiting FTL to a special frame, such as the CMB rest frame. I don't think anyone has been able to directly discredit that yet.. though we don't necessarily like it :-)
Im sort of waiting for some wizzes at relativity to come along and pull the rug out from under that one with a specific example that shows it still produces paradoxes. That is where we are at the moment.
Having suggested the existence of a special frame to begin with, I feel I should clarify. If there is such a thing as a special frame that you limit FTL to, the entire theory of relativity collapses, because this directly contradicts its most fundamental assumption. I have no idea what, if anything, you could replace it with unless you want to ignore untold numbers of experimental results.
So you're trying to find rules obeying relativity to do something that relativity absolutely prohibits?
Which is why the best solution I could come up with is to break the one fundamental assumption underlying relativity.
My post from earlier today does not contradict relativity. What are the "fundamental assumptions", or the Postulates of Special Relativity?
1. The laws of physics are the same in all inertial frames of reference.
2. The speed of light in vacuum has the same value c in all inertial frames of reference.
Regarding the 2nd postulate; as I said in my post, M, L & T are scaled as functions of K. Rulers and clocks are "normalized" such that the value of c is constant in all "local" inertial reference frames.
Regarding the 1st postulate; using the dimensional conversions,
Mass M = M0*K3/2
Length L = L0/√K
Time T = T0*√K
Calculate how Forces depend on K. Simple;
Force = (Mass)*(Length)/(Time)2 = (M0*K3/2)*(L0/√K)/(T0*√K)2
So => M*L/T2 = M0*L0/T02
In other words, the forces we measure in experiments are completely independent of the local value of K. So all inertial reference frames will experience the same forces and have the same results to ALL experiments that verify SR and GR. The effects of K cannot be measured "locally" because our rulers and clocks are renormalized. Therefore, the only change to the postulates is to add the word "local". Nothing else in SR or GR changes, except the interpretation of what we already know.
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Having suggested the existence of a special frame to begin with, I feel I should clarify. If there is such a thing as a special frame that you limit FTL to, the entire theory of relativity collapses, because this directly contradicts its most fundamental assumption. I have no idea what, if anything, you could replace it with unless you want to ignore untold numbers of experimental results.
So you're trying to find rules obeying relativity to do something that relativity absolutely prohibits?
Which is why the best solution I could come up with is to break the one fundamental assumption underlying relativity.
Im not sure I am understanding you. We are probably saying the same thing and just wording it differently. To be clear, you are not talking about changing the universe in a way that invalidates current experiments, correct? All those experiments have to still deliver the same outcomes.
Breaking the assumption is fine, If I know what you mean. Relativity can be perfect like a sphere without being a statement that there is no such thing as a cube, or that you won't suddenly come across a cube embedded in your sphere.
This is why Im only concerned with paradoxes, or solutions that require current experiments to suddenly deliver different outcomes, and Im still not convinced there is not still a nasty paradox hidden in there somewhere. Im still expecting someone to pull the rug out from under this with an example that shows it is just as nonsensical as general FTL.
I found this. I can't really make heads or tails out of it yet.
https://arxiv.org/pdf/1407.2528.pdf (https://arxiv.org/pdf/1407.2528.pdf)
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I know this. I've been trying to teach people this alternative for a long time. Eventually, some people do get it, but others just want to argue. If we work together, we can make it so that FTL is possible and the paradoxes are not. That's my goal. Is it yours?
And this is what is wrong with your entire argument. You cannot make anything so simply by working toward it. Things are so or not so regardless of what you want. You are engaged in motivated reasoning toward a goal. That's how creationists believe in a 7000 year old earth. That's how the flat earth society is still a thing. If you are willing to bend logic reason and evidence to fit your preselected desire then you have killed science. Your goal should not be proving FLT is possible. Your goal should be understanding the truth what ever it may be.
Nobody wants the limit of light speed. There is no vast political movement to prevent FTL travel. There is no conspiracy to hide the truth. It is just what the evidence points to. Now you are free to disagree with almost the entire scientific community if you wish. And I wish you luck. Honestly I do. It would be wonderful. But at the same time I gotta be honest and say that your chances are better buying a lotto ticket.
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The issue with the twin paradox is that we're trying to describe it under Special Relativity and that does not include accelerating frames of reference. It's above my pay grade, but I bet if we did the math under GR there would not be a problem since we can include the acceleration of the spaceship.
The twin paradox is specifically a special relativity phenomena. General relativity reduces to special relativity in the flat space that we use to describe the twin paradox. There is literally no math to do.
In both general relativity and special relativity things that are simultaneous in one frame are not simultaneous in another. This is the central fact that fuels the twin paradox. It is built in to the geometry of spacetime.
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I know this. I've been trying to teach people this alternative for a long time. Eventually, some people do get it, but others just want to argue. If we work together, we can make it so that FTL is possible and the paradoxes are not. That's my goal. Is it yours?
And this is what is wrong with your entire argument. You cannot make anything so simply by working toward it.
??? That's an odd thing to say. I've built 3 successful businesses in my career "by working toward it".
Things are so or not so regardless of what you want. You are engaged in motivated reasoning toward a goal. That's how creationists believe in a 7000 year old earth. That's how the flat earth society is still a thing. If you are willing to bend logic reason and evidence to fit your preselected desire then you have killed science. Your goal should not be proving FLT is possible. Your goal should be understanding the truth what ever it may be.
Nobody wants the limit of light speed. There is no vast political movement to prevent FTL travel. There is no conspiracy to hide the truth. It is just what the evidence points to. Now you are free to disagree with almost the entire scientific community if you wish. And I wish you luck. Honestly I do. It would be wonderful. But at the same time I gotta be honest and say that your chances are better buying a lotto ticket.
Given that the previous two papers I wrote were both published with very little objection from the referees, I think my chances are a lot better than that. My model does not invalidate any part of GR or SR. It just invalidates the misinterpretations and introduces a different interpretation of what we already know to be true.
Also, I am not bending logic, reason or evidence. I have many verifiable references.
References
2. P. W. Milonni, The Quantum Vacuum – An Introduction to Quantum Electrodynamics, Academic Press, Inc. 1994. Secs., 2.6 - 2.13, 3.1 - 3.3, 5.1 - 5.4, 11.8. (Book) (and Appendix A & B)
3. H. E. Puthoff, Advanced Space Propulsion Based on Vacuum (Spacetime Metric) Engineering, JBIS, Vol. 63, pp. 82-89, http://www.earthtech.org/publications/puthoff_jbis.pdf (http://www.earthtech.org/publications/puthoff_jbis.pdf), Nov. 2010.
4. H. E. Puthoff, Polarizable-Vacuum (PV) Representation of General Relativity, /gr-qc/9909037 v2, Sept., 1999. https://arxiv.org/pdf/gr-qc/9909037.pdf (https://arxiv.org/pdf/gr-qc/9909037.pdf)(Last Accessed 16, July 2016)
5. H. E. Puthoff, et. Al., Engineering the Zero-Point Field and Polarizable Vacuum for Interstellar Flight, JBIS, Vol. 55, pp.137-144, /astro-ph/0107316, Jul. 2001. (Last Accessed 16, July 2016)
7. H. E. Puthoff, Quantum Ground States as Equilibrium Particle-Vacuum Interaction States, Quantum Stud.: Math. Found., Vol. 3, No.1, pp.5-10, 2016. https://link.springer.com/article/10.1007/s40509-015-0055-5 (https://link.springer.com/article/10.1007/s40509-015-0055-5)
8. T. J. Desiato, The Electromagnetic Quantum Vacuum Warp Drive, JBIS, Vol. 68, pp. 347-353. Apr. 2016. http://www.jbis.org.uk/paper.php?p=2015.68.347 (http://www.jbis.org.uk/paper.php?p=2015.68.347)
9. P. W. Milonni, Quantum Mechanics of the Einstein-Hopf Model, Am. J. Phys. 49, pg. 177 (1981a)
10. P. W. Milonni, Radiation Reaction and the Nonrelativistic Theory of the Electron, Phys. Lett. 82A, pg. 225. (1981b)
11. H. E. Puthoff, Casimir Vacuum Energy and the Semiclassical Electron, International Journal of Theoretical Physics 46, No. 12, pp 3005-3008 http://www.earthtech.org/publications/Puthoff/ (http://www.earthtech.org/publications/Puthoff/), May 2007. Last Accessed 16, July 2016)
12. Larmor Formula, en.wikipedia.org/wiki/Larmor_formula, (Last Accessed, 16, July 2016)
13. Schwarzschild Metric, en.wikipedia.org/wiki/Schwarzschild_metric, (Last Accessed 16, July 2016)
14. T. J. Desiato, General Relativity and the Polarizable Vacuum, vixra.org/pdf/1203.0100v1.pdf, (http://vixra.org/pdf/1203.0100v1.pdf,) 12 March, 2006. (Last Accessed 16, July 2016)
15. J. G. Depp, Polarizable Vacuum and the Schwarzschild Solution, researchgate.net/publication/265111294_Polarizable_Vacuum_and_the_Schwarzschild_Solution (http://researchgate.net/publication/265111294_Polarizable_Vacuum_and_the_Schwarzschild_Solution), May 2005. (Last Accessed, 16, July 2016)
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I think I just had an interesting insight about the "CMB rest frame as special" solution to FTL paradoxes. It gives me more confidence that it really does avoid all paradoxes.
My insight was that "simultaneous" in this context can be defined as all points where the CMB is the same temperature. For example if we had 'Instantaneous' travel, this would mean we were sliding around an isosurface through space-time where the temperature of the CMB (in the CMB rest frame) is exactly 2.725°. If we were using our FTL 13 billion years ago, the universe would be orange and our instantaneous travel would take us to another point of the universe with the exact same shade of orange.
FTL that is less than instantaneous would deliver you to some point in space time where the temperature is a tiny bit lower.. never higher.
Relativistic flight also obeys this rule.
If our FTL obeys this simple rule, I think we can be confident that no combination of FTL and relativistic flight would ever deliver you back to your starting point before you left.
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Having suggested the existence of a special frame to begin with, I feel I should clarify. If there is such a thing as a special frame that you limit FTL to, the entire theory of relativity collapses, because this directly contradicts its most fundamental assumption. I have no idea what, if anything, you could replace it with unless you want to ignore untold numbers of experimental results.
So you're trying to find rules obeying relativity to do something that relativity absolutely prohibits?
Which is why the best solution I could come up with is to break the one fundamental assumption underlying relativity.
Im not sure I am understanding you. We are probably saying the same thing and just wording it differently. To be clear, you are not talking about changing the universe in a way that invalidates current experiments, correct? All those experiments have to still deliver the same outcomes.
Breaking the assumption is fine, If I know what you mean. Relativity can be perfect like a sphere without being a statement that there is no such thing as a cube, or that you won't suddenly come across a cube embedded in your sphere.
This is why Im only concerned with paradoxes, or solutions that require current experiments to suddenly deliver different outcomes, and Im still not convinced there is not still a nasty paradox hidden in there somewhere. Im still expecting someone to pull the rug out from under this with an example that shows it is just as nonsensical as general FTL.
The problem that happens when we break the assumption "no reference frame is special" is that we have a bunch of experimental data that stands strongly in support of that assumption. It is not clear if there is any way to explain the data other than that assumption being true. In addition to experiments that directly support the assumption, there are also all of the other results of relativity that have proven accurate. If you break the fundamental assumption of relativity, it is hard to determine whether or not those results even make sense anymore.
If we work together, we can make it so that FTL is possible and the paradoxes are not. That's my goal. Is it yours?
I would like this to be possible, and I am fine with trying to come up with a theory that would allow FTL. Ppnl does have a ppoint that we need to remember that we can't control how the universe works, so if the universe really says that FTL results in paradoxes/is impossible, then nothing we can do will change that.
It will probably be a few days before I can give a detailed response, but as an item for you to think on for now: Special relativity and everything I have been discussing involves flat space-time which, if I am reading what you wrote correctly, corresponds to K=1 everywhere. Even if you say that the FTL requires curvature, that curvature would be fairly local, and sufficient separation of observers and between the ships should be possible where the analysis can be done just considering the flat space time, in the same way that the twin paradox can be resolved without directly calculating what the traveler experiences during acceleration.
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If we work together, we can make it so that FTL is possible and the paradoxes are not. That's my goal. Is it yours?
I would like this to be possible, and I am fine with trying to come up with a theory that would allow FTL. Ppnl does have a ppoint that we need to remember that we can't control how the universe works, so if the universe really says that FTL results in paradoxes/is impossible, then nothing we can do will change that.
It will probably be a few days before I can give a detailed response, but as an item for you to think on for now: Special relativity and everything I have been discussing involves flat space-time which, if I am reading what you wrote correctly, corresponds to K=1 everywhere. Even if you say that the FTL requires curvature, that curvature would be fairly local, and sufficient separation of observers and between the ships should be possible where the analysis can be done just considering the flat space time, in the same way that the twin paradox can be resolved without directly calculating what the traveler experiences during acceleration.
One correction about what is "flat space-time". K=constant is flat space-time. It does not need to be K=1. It needs to be such that the derivatives of K wrt space-time vanish. i.e., the gradients of K are 0. Then space-time is flat, but the value of K can be "anything" greater than 0. What I said is; "we can have an infinite number of inertial reference frames, each with a different value of K", when K is a "constant" in that local region. We can only see the relative value of K, when we are comparing two distant regions of space-time, and we can only measure gravitational fields when the derivatives of K are non-zero.
As long as our measurements of "force" are unaffected by the value of K in the local inertial frame, then all of the experiments we can do, EM or otherwise, are unaffected and "the laws of physics are the same in all "local" inertial frames", despite the fact that the "scale" of the space-time has changed conformally.
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In general, is this a debate over whether Alcubierre warp bubbles or wormholes could ever exist, or whether literal FTT travel through space cannot exist? Thanks.
Hi Bob012345,
When I started this thread, the goal was to find a definition of FTL that avoids paradox. It is not about the theory of any particular method or whether it actually exists, just if you can describe what you are claiming it would allow you to do.
Another way of looking at it could be "Guilt-free FTL rules for HardSF writers". You don't need to explain the machine. It Glows. It makes noises. Things spin. But you do have to explain the characters. Who can understand a universe full of characters living in a universe where you could create a paradox with a few simple steps, and no one does it, and no one talks about it?
I started this thread thinking we could demonstrate a paradox with a single FTL flight. At the moment we have a claim that you can avoid all paradoxes by limiting FTL to a special frame, such as the CMB rest frame. I don't think anyone has been able to directly discredit that yet.. though we don't necessarily like it :-)
Im sort of waiting for some wizzes at relativity to come along and pull the rug out from under that one with a specific example that shows it still produces paradoxes. That is where we are at the moment.
One really weird thing about a universe like that, is that travelling in one particular direction you would be travelling into the past, just not far enough to get back in time to cause paradox. So I guess your friend could jump a lightyear to the left and you could see them immediately jump out of their ship and start waving to you, because all this happened a year ago over there, and the light has been travelling towards you all that time!
Thanks. All of you interested in these ideas should view the 2004 film Primer. It was a very low budget ($7000) independent film that explored what happens when a small group of guys do a tech startup (in a garage no less) and discover an effect that can be made into a time machine. Needless to say they are quickly confronted with an exponentially growing complexity of potential 'problems' and issues. It's fun but really requires concentration to figure out what's going on with nested loops of time travel and time machines containing other time machines and the consequences that follow. I'm not attached in any way to the film financially.
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Thanks. All of you interested in these ideas should view the 2004 film Primer.
I saw that. Being time-travel, it is an example of one of the possible absurdities you could encounter here also, with undefined FTL.
At the moment my feeling from this thread is that at least I have found a guilt-free way to watch SF with FTL. I don't need to worry about why the characters are not all thinking about killing their grandfathers. This in no way argues that FTL is shoehorned into the laws of physics, but at least forms of it can be described without paradox, apparently.
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With the Alcubierre warp drive, doesn't the ship stay at local time, even when you get to the other star because it is the fabric of spacetime around the ship moving, and not the ship?
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With the Alcubierre warp drive, doesn't the ship stay at local time, even when you get to the other star because it is the fabric of spacetime around the ship moving, and not the ship?
The problem is that you can produce paradoxes just by sending messages. You can ignore what the postman experiences.
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Why this longing for FTL to be possible and the desire to brush off what science tells us? Is it because we wish we could talk to technological extraterrestrials, visit them, trade with them (maybe have sex, too)?
I can dig that. Curiosity and sociability are human fundamentals.
This would be a lot less pressing an issue if instead of being stuck out in the sticks we lived in the galactic core, where stars crowd in on each other, so close you can almost touch them and the folks who live on their planets. Moe's cantina on Tattooine would be real!
Of course, the natural environment would be much more hazardous (close-by supernovae, gamma-ray bursts, disrupted planetary orbits) but there's always tradeoffs. Live in the inner city within walking distance of theater and opera? Wonderful ... if you don't mind getting mugged :)
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This would be a lot less pressing an issue if instead of being stuck out in the sticks we lived in the galactic core, where stars crowd in on each other, so close you can almost touch them and the folks who live on their planets. Moe's cantina on Tattooine would be real!
Im actually very enthusiastic of a good hard SF set in just this solar system. That is why I have that list in my tag line. I think most people underestimate how many worlds there are right here. I have seen estimates of up to 10,000 dwarf planets if you include the Oort cloud. Each of those could probably support a civilisation as large as we currently have on earth, because on earth we only exploit a tiny scummy layer on the surface. There is a heck of a lot of worlds to colonise before we run out and need to worry about getting to another star.
I know that is very off topic. Just happens to be one of my hobby horses.
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I found this. I can't really make heads or tails out of it yet.
https://arxiv.org/pdf/1407.2528.pdf (https://arxiv.org/pdf/1407.2528.pdf)
I think I figured out what they did.
The short version: They assume that FTL is effectively only possible in one direction, which does prevent time travel scenarios like the ones we have discussed, since it prevents a return trip. It also makes one spatial direction "special" in a way that none have been observed to be.
The long version: They start out doing SR with just 1 spatial dimension. Because space and time are symmetric to each other they ignore which axis is the spatial one, and which is time. They then define STL and FTL as relative properties (2 STL observers agree on which axis is "time") They then apply a "same future" assumption that any 2 things that are relatively STL agree on which direction is the "future." When they do this treating space and time as perfectly interchangeable, they create a special spatial direction. To be honest, I didn't put in enough time to fully follow the generalization to 3 spatial dimensions, but it seems they kept this flaw of assuming certain directions are special.
They actually say in their conclusions: On the other hand, it is certainly possible to construct logically sensible models of spacetime in which observers can disagree as to the direction of time’s arrow. Our results do not undermine those constructions, but they do force us to re-examine which aspects of these models are actually responsible for any apparent paradoxes.
This confirms for me that they recognize the part I pointed out as being where their proof includes an unfounded assumption. The actual version everyone else assumes based on available evidence: "only STL observers agree on the direction of time's arrow, because for FTL observers to do so requires something to be special about certain spatial directions." It is good to point out the implicit existence of this assumption, but the way they word it makes it sound like they assume that if forward and back aren't special for space, they must not be for time either.
While they claim their model is consistent with the principle of relativity, they use a narrow definition of the principle of relativity, and I believe their construction of special spatial directions (+x and -x directions being distinguishable by which of those directions FTL particles can move in) actually undermines the more general concept behind relativity. They might get away with it since may be that in their model only FTL particles are affected by the special direction.
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One really weird thing about a universe like that, is that travelling in one particular direction you would be travelling into the past, just not far enough to get back in time to cause paradox. So I guess your friend could jump a lightyear to the left and you could see them immediately jump out of their ship and start waving to you, because all this happened a year ago over there, and the light has been travelling towards you all that time!
What? No. An FTL jump of one light year means they're over there now. The light starts traveling now. It shows up a year from now.
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No. An FTL jump of one light year means they're over there now.
That is the problem with relativity. There is no such thing as "They're over there now", at least not that has meaning to all observers. If two distant events are simultaneous to one observer, typically they will not be simultaneous to another observer moving with a different relative velocity.
It is really what this whole thread is about.
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No. An FTL jump of one light year means they're over there now.
That is the problem with relativity. There is no such thing as "They're over there now", at least not that has meaning to all observers. If two distant events are simultaneous to one observer, typically they will not be simultaneous to another observer moving with a different relative velocity.
It is really what this whole thread is about.
I've read through most of this thread, and it seems to be about two completely different things. There's a theoretical FTL jump, which bypasses all aspects of relativity, and then there's flying through space at near the speed of light and experiencing time dilation. One is FTL, one is sublight. They're not the same.
There absolutely is "over there now". A point in space one light year away exists right now. It is occupied by matter and energy right now. A photon of light originating there right now arrives here exactly one year from now. If I could somehow teleport myself to that point right now and turn on a radio transmitter, that signal does not start travelling a year ago. It starts now.
We send messages at the speed of light all the time and it doesn't cause a paradox. I can mail a letter from Chicago to New York. I can then call New York and send the contents of that letter at light speed, such that the information arrives before my physical letter does. It doesn't change the order of events, doesn't send information back in time.
If I use an ansible (https://en.wikipedia.org/wiki/Ansible) to control Curiosity on Mars in real time (no ~15 minute delay) I am controlling it NOW. Not in the past, not in the future. I can't send messages into the past or the future, I can only send them to now. An ansible signal traveling to Mars faster than a radio wave doesn't mean anything more than my phone call reaching New York faster than my letter.
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No. An FTL jump of one light year means they're over there now.
That is the problem with relativity. There is no such thing as "They're over there now", at least not that has meaning to all observers. If two distant events are simultaneous to one observer, typically they will not be simultaneous to another observer moving with a different relative velocity.
It is really what this whole thread is about.
I've read through most of this thread, and it seems to be about two completely different things. There's a theoretical FTL jump, which bypasses all aspects of relativity, and then there's flying through space at near the speed of light and experiencing time dilation. One is FTL, one is sublight. They're not the same.
I think you may have been confused by warptech's posts since he kept talking about the time experienced by the observer in situations where it was irrelevant to the discussion. As a result, we ended up discussing the "twin paradox" to help get on the same page, I think it has helped, but I have to go over his recent posts closely again to see if we really are on the same page.
There absolutely is "over there now".
No, there absolutely is not. If you don't understand this, you need to go find a good explanation of relativity somewhere and learn about it.
Of course sending signals at light speed doesn't cause a paradox, because light speed really is the "speed of causality" as described by one of the videos posted earlier in this thread.
However, anything in between "when the light you currently are receiving from a source was sent" and "when someone would receive light that you sent now" are all equivalently "now." For Mars, this means there typically is a half hour range where "ansibles" moving at different speeds could be communicating with different times in that range.
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Earth and Mars being 30 light minutes apart has nothing to do with relativity or paradoxes. They are both existing in space together at the exact same moments in time. Their clocks may be moving at slightly different rates. But once a moment of time, the same moment for both, has become past it is past.
1) Via radio, I tell Curiosity to move 10m. It takes Curiosity 10 minutes to move those 10m. 60 minutes later I get confirmation my command was received, 70 minutes later I get confirmation the drive is complete.
2) Via ansible, I tell Curiosity to move 10m. Milliseconds later I get confirmation of message receipt, 10 minutes later confirmation the drive is complete.
What is different other than the elimination of 60 minutes of delay?
Speed of causality is speed of light only because we don't know how to send a faster signal. If we can send faster signals, then speed of causality becomes that new faster speed. Of course an ansible communicates with a different time. It communicates with now as opposed to 30 minutes from now. That doesn't equal time travel, sending messages into the past or creating a paradox.
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The problem is that one ansible with high relative velocity would be communicating with 10 minutes ago so you could see the results before you sent the command.
Go read this, and ask an informed question afterwards if you still don't get it.
https://en.wikipedia.org/wiki/Relativity_of_simultaneity
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Earth and Mars being 30 light minutes apart has nothing to do with relativity or paradoxes. They are both existing in space together at the exact same moments in time. Their clocks may be moving at slightly different rates. But once a moment of time, the same moment for both, has become past it is past.
1) Via radio, I tell Curiosity to move 10m. It takes Curiosity 10 minutes to move those 10m. 60 minutes later I get confirmation my command was received, 70 minutes later I get confirmation the drive is complete.
2) Via ansible, I tell Curiosity to move 10m. Milliseconds later I get confirmation of message receipt, 10 minutes later confirmation the drive is complete.
What is different other than the elimination of 60 minutes of delay?
Speed of causality is speed of light only because we don't know how to send a faster signal. If we can send faster signals, then speed of causality becomes that new faster speed. Of course an ansible communicates with a different time. It communicates with now as opposed to 30 minutes from now. That doesn't equal time travel, sending messages into the past or creating a paradox.
I suggest working through an equivalent problem with a two speed system, sound waves and light waves. Assume some information you can hear with sound to know it's happened and then respond and the light channel is then added to compare the way information is perceived. Here is an interesting, though trivial example of time reversed events from the past. In WW2 London, the V-2 rockets landed with no warning. After they exploded, the sound of the rockets approach came roaring in further terrifying shocked residents.
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That's not time reversal. This reminds me of when I was in Hong Kong on Valentine's day. I called my wife in Chicago on 2/14 at 7am my time to say "Happy Valentine's day!". And her reply was "How are you in the future? It's not Valentine's day yet". Because for her, it was still the 13th. Yet we were speaking to each other at the exact same moment in time, regardless of our frame of reference.
Relativity of Simultaneity deals with the apparent order of events, as observed by moving observers. It says nothing about what the order actually is.
The problem is that one ansible with high relative velocity would be communicating with 10 minutes ago so you could see the results before you sent the command.
A ship with an ansible at high relative velocity experiences time dilation yes. But all clocks keep moving forward, only the rates are different. At what point does the ship travel 10 minutes into the past?
Say a ship is moving ~0.93c and has a time dilation factor of 3. It sends a message via ansilbe that says "Call back in 3 minutes". The call comes in 1 minute later ship time. The reply will always come after the message.
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A different example is our ability to calculate times for EDL, gravity slingshots, etc. For Curiosity's EDL, the light speed delay was 13m, 48s. New Horizons at Pluto was 4.5h. For both of those events, the mission planners had to be able to define a now. Curiosity hits the atmosphere now. Pluto is in the camera field of view now. It doesn't matter that those events took place outside our light cone and we couldn't directly observe them. They happened at exact moments in time, at a particular position in space and we here on Earth knew what those were.
Ansible communication to those probes changes nothing. Making an FTL jump out to watch them occur changes nothing.
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Relativity of Simultaneity deals with the apparent order of events, as observed by moving observers. It says nothing about what the order actually is.
No it has to do with the actual order of events. No the order when light from them arrives. No inertial reference frame is special, so the definition of now for a moving observer is equally valid, and the moving observer's ansible would send a signal to t = -10 in the Earth frame, which means that the Earth frame ansible would receive confirmation of the signal reception 10 minutes before the signal is sent.
A ship with an ansible at high relative velocity experiences time dilation yes. But all clocks keep moving forward, only the rates are different. At what point does the ship travel 10 minutes into the past?
No, not discussing time dilation. The ship does not travel into the past in this scenario. When something accelerates to a high speed, its time axis shifts changing the definition of "now" for distant objects. This means its ansible signals can travel into the past or receive messages from the future according to an observer in the original frame.
Say a ship is moving ~0.93c and has a time dilation factor of 3. It sends a message via ansilbe that says "Call back in 3 minutes". The call comes in 1 minute later ship time. The reply will always come after the message.
You are simply not discussing the same case as me, 2 sets of ansibles moving at different speeds.
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Ansible signals don't travel into the past or future. They are simply instantaneous. If the signals are in the past, then the ship is in the past too. But the ship didn't travel into the past, so we have a contradiction.
Edit: I retract all this, the time shift isn't real, it's an illusion of geometry. The only thing real is relativistic time dilation.
I think you're ignoring the amount of time it takes a ship to accelerate and achieve the time axis shift, with respect to the now. A ship would have to accelerate nearly instantaneously, requiring nearly infinite energy. I'm comfortable ignoring that case.
If it takes a ship just 10.001 minutes to time shift -10 minutes, then at no point is the ship actually in the past with respect to the original frame. It may appear from the ground to have reached velocity in 0.001 minutes, but I'd postulate that a ship cannot achieve a true negative time shift that would result in ansible signals creating a paradox.
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Instantaneous in what frame?
The scenario I described can have everything already moving at said speed, so the time for acceleration is irrelevant. Also, you can just pick a further away other end of the ansible if you did want to have enough time to accelerate.
You clearly have not read the link I posted, or watched the intro to relativity video posted early in this thread. If you don't make any attempt to understand the resources that you have been pointed to, there is no point in me retyping explanations that are widely available.
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(this comment meant to apply to "New Physics" in general, not necessarily to this thread)
In the old Bad Astronomer forum, there was a section called Against the Mainstream (if I remember correctly) where anyone could present their pet theory proving Einstein (or whomever) wrong. They had a fairly rigorous set-up, with claimants having to agree to abide by certain rules, such as responding to questions/objections promptly or the thread would be closed. Non-responsive replies and willful obtuseness also could lead to the thread being shut down.
It was a big workload on the moderators, perhaps one of the reasons why that forum is now defunct. However, they did keep the queue moving and prevented belligerent or slow claimants from clogging up the works.
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I read the link again and watched the videos. All there is, is time dilation, light cones and some graphs based on the theory that nothing can go FTL. But plotting an FTL course through non-FTL theory and getting a nonsense result doesn't equal time travel. There is nothing that indicates at exactly what point an FTL ship actually goes backwards in time. It equals an inability of the theory to describe what is actually happening.
Instantaneous in all frames. This isn't a thought experiment. There is an entire galaxy of actual matter out there and all of it exists right now. Clocks running at different rates does not invalidate a common now.
I can envision a galaxy wide civil alert system. "Warning", the ansible calls out, "Eta Carine just went supernova. The effect will be visible in your section of the galaxy in 7500 Earth years." That would be an actual event, fixed in time and space. Different observers see it happening at different times, but there was only one now at which it did occur. The shockwave will spread through the neighboring stars and impact them at specific singular points in time. An FTL ship could observe all of that as it actually occurs. Regardless of what any relativistic ships plodding along think they see years later.
All the clocks out there are only ticking forward. Their rate doesn't matter, their change in rate doesn't matter. If the speed of light is the speed of causality, then if FTL is possible, it simply means a new speed of causality. No time travel, no paradox.
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I read the link again and watched the videos. All there is, is time dilation, light cones and some graphs based on the theory that nothing can go FTL. But plotting an FTL course through non-FTL theory and getting a nonsense result doesn't equal time travel. There is nothing that indicates at exactly what point an FTL ship actually goes backwards in time. It equals an inability of the theory to describe what is actually happening.
It is not a limitation of the ability of the theory to describe what is happening, but of your understanding of the theory. An FTL course in special relativity just means you are discussing spacelike separated events. For any pair of spacelike separated events, there is always a frame where they happen in opposite order.
Instantaneous in all frames.
You are going to have to let go of your intuition. Your intuition says that their is a single "now" that everyone agrees on. This however is not true when you get to relativistic speeds.
The scenario you wrote down is incompatible with the fact that observers in in different reference frames all see light moving at the speed of light relative to themselves, regardless of how fast they are moving relative to anything else. If you try to write down a set of rules that are consistent with this, you end up with the Lorentz transformations, which are the basis for special relativity.
Lets work through an example:
There is a ship flying past earth at speed 0.6 c. We define the origin of both the ship's reference frame and the Earth's reference frame to be the event when the ship passes the Earth.
Lets also say that there are 2 star systems at x = -10 and x = -5 in the Earth frame (opposite direction that the ship is travelling in, and at rest in the Earth frame.)
The star at x = -10 goes nova at time t = 0, so we can define to more events in spacetime at x=-10, t = 0, when the star goes nova, and x = -5, t = 5 when the nova is seen at the second star system.
Using the Lorentz transformation, we can see when these events happen in the ship frame (This is when they happen, not when the light reaches the ship)
The gamma factor for the ship is 1.25.
For the nova:
t' = 1.25*(0 - (0.6*-10)) = 7.5 (7.5 years in the future)
x' = 1.25*(-10 - 0) = -12.5 light years
For the star system seeing the nova:
t' = 1.25*(5 - (0.6*-5)) = 10
x' = 1.25*(-5 - 0.6*5) = -10 light years
You can see that the speed of light is the same, it takes 2.5 years for light to travel the 2.5 light years between these 2 events in the ship frame.
You can also see how a paradox can come about if you allow FTL, because as the ship is passing Earth an ansible on Earth would receive the communication that the star went nova. They can relay this information to the ship that is passing by Earth. For the ship, the star will not go nova for 7.5 years. If it sends an ansible message to that star, the message will arrive years before the star goes nova, because "now" for the ship is different from "now" on Earth.
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It's becoming clear to me that the paradox is not created by FTL, but by the Lorentz transformations trying to define relativistic travel.
You say that the nova star and second star system are 2.5ly apart in ship frame. But the two stars are actually 5ly apart. The ship would know that from its charts. It would know that light cannot travel 5ly in 2.5yr. The speed of light did not increase and the two stars did not move closer together. It is the time dilation on the ship that makes it appear that the two events are 2.5ly apart. By that, the ship knows that it is not an "at rest" reference frame, but is suffering relativistic effects.
Similarly, the t's for the two events ship frame result from plotting world lines for those events in its clock slowed reference frame, but those are not real, they are illusions. The nova, the 2nd star system, Earth and the ship all exist at real points in space. Nothing is moving except the ship and it is not going backwards in time. An ansible network in constant communication with all 4 as the ship accelerates from 0 to 0.6c would observe the time dilation, but would only see the ship's clock continuing to move forward. At no point does it slip into the past. The ansible keeps all the clocks in sync and exposes the illusion. But there is no paradox, information cannot be sent into the past.
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It's becoming clear to me that the paradox is not created by FTL, but by the Lorentz transformations trying to define relativistic travel.
You say that the nova star and second star system are 2.5ly apart in ship frame. But the two stars are actually 5ly apart. The ship would know that from its charts. It would know that light cannot travel 5ly in 2.5yr. The speed of light did not increase and the two stars did not move closer together. It is the time dilation on the ship that makes it appear that the two events are 2.5ly apart. By that, the ship knows that it is not an "at rest" reference frame, but is suffering relativistic effects.
Similarly, the t's for the two events ship frame result from plotting world lines for those events in its clock slowed reference frame, but those are not real, they are illusions. The nova, the 2nd star system, Earth and the ship all exist at real points in space. Nothing is moving except the ship and it is not going backwards in time. An ansible network in constant communication with all 4 as the ship accelerates from 0 to 0.6c would observe the time dilation, but would only see the ship's clock continuing to move forward. At no point does it slip into the past. The ansible keeps all the clocks in sync and exposes the illusion. But there is no paradox, information cannot be sent into the past.
You're effectively saying that the problem is created by the theory of relativity, not FTL. Sure, if you're willing to give up Einstein's theory of relativity FTL could well be possible. But it's going to be hard to convince anyone else...
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You say that the nova star and second star system are 2.5ly apart in ship frame.
No, due to length contraction, they are 5/1.25 = 4 light years apart. The second star spends the next 2.5 years travelling towards where the nova happened at 0.6c so the time that passes in the ship frame between the 2 events is 2.5 years. (The nova remnants are also moving at the same speed so they remain 4 light years away from the second star.)
But the two stars are actually 5ly apart. The ship would know that from its charts.
They are NOT 5 light years apart. They are 4 light years apart in the ship frame. Saying that they are 5 light years apart would mean that the Earth frame is some kind of special rest frame. This is simply untrue.
It is the time dilation on the ship that makes it appear that the two events are 2.5ly apart. By that, the ship knows that it is not an "at rest" reference frame, but is suffering relativistic effects.
No. You seemed to have missed this point: EVERY inertial reference frame is an "at rest frame." From the ship's perspective it is the clocks on Earth that run slow.
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Calling time dialation an "illusion" indicates a very basic flaw in understanding to me. Saying that nothing is moving except the ship doesn't make much sense. Everything is moving relative to everyting else. There are relativistic effects with any two objects not at exactly the same reference. Just not enough to measure in some cases. The only illusion is that all these twisted analogies have much to do with the world. I haven't seen an argument in here that doesn't assume some state that has no basis in reality and completely invalidates the conclusion.
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Time dilation is not an illusion, that is the only thing that is real. The gamma factor of relativistic travel is real and that is what separates the reference frames from each other. The Solar system and surrounding stars are moving at about 0.00075c. That is what separates our reference frame from that of a 0.6c ship.
The ship knows the two stars were 5ly apart when it was also moving at 0.00075c and are still 5ly apart. The acceleration of the ship did not cause the second star to also accelerate to 0.6c (where does that energy come from?). That is part of the illusion. The ship observes the two stars as 4ly apart (not 2.5 sorry) and knows that time dilation is distorting its observations of surrounding objects.
I'm not giving up the Theory of Relativity. I'm giving up a graphical projection that says a relativistic ship has time shifted into the past. It hasn't.
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You can also see how a paradox can come about if you allow FTL, because as the ship is passing Earth an ansible on Earth would receive the communication that the star went nova. They can relay this information to the ship that is passing by Earth. For the ship, the star will not go nova for 7.5 years. If it sends an ansible message to that star, the message will arrive years before the star goes nova, because "now" for the ship is different from "now" on Earth.
The message sent "to" that star is moving "toward" the star, not away from it. In the frame of the message, the space-time axis must rotate so as to approach the star, not move away from it as in the ship's frame. The paradox is caused by ignoring this 3rd reference frame of the message "approaching" the star.
IMO, I agree with the one statement in that paper I found, and that is; if we can't travel into the past while at rest or moving STL, then we can't do it moving FTL either, because all motion is relative.
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Time dilation is not an illusion, that is the only thing that is real. The gamma factor of relativistic travel is real and that is what separates the reference frames from each other. The Solar system and surrounding stars are moving at about 0.00075c. That is what separates our reference frame from that of a 0.6c ship.
Moving at 0.00075c or 0.6c relative to what? You seem to be assuming that there is some special reference frame, which is in contradiction with relativity.
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Time dilation is not an illusion, that is the only thing that is real. The gamma factor of relativistic travel is real and that is what separates the reference frames from each other. The Solar system and surrounding stars are moving at about 0.00075c. That is what separates our reference frame from that of a 0.6c ship.
Moving relative to what?
The ship observes the two stars as 4ly apart (not 2.5 sorry) and knows that time dilation is distorting its observations of surrounding objects.
Read my post again.
Due to length contraction, they are 5/1.25 = 4 light years apart. The second star spends the next 2.5 years travelling towards where the nova happened at 0.6c so the time that passes in the ship frame between the 2 events is 2.5 years. (The nova remnants are also moving at the same speed so they remain 4 light years away from the second star.)
I'm not giving up the Theory of Relativity. I'm giving up a graphical projection that says a relativistic ship has time shifted into the past. It hasn't.
The very foundation of relativity is that all inertial reference frames are equivalent. If you give this up, the rest goes out the window. The "graphical representation" simply reflects the basic math of the situation.
Without the length contraction and the temporal shift of the events, there is no way to explain the fact that using the time measured by the ship and distance measured by the ship, light still would be travelling at c towards the (stationary) ship.
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The message sent "to" that star is moving "toward" the star, not away from it. In the frame of the message, the space-time axis must rotate so as to approach the star, not move away from it as in the ship's frame. The paradox is caused by ignoring this 3rd reference frame of the message "approaching" the star.
IMO, I agree with the one statement in that paper I found, and that is; if we can't travel into the past while at rest or moving STL, then we can't do it moving FTL either, because all motion is relative.
Defining an FTL frame causes problems, so to work around that you can simply and validly just look at what happens in the STL inertial frames.
In the Earth frame, the ansible sends information from the nova to Earth travelling on an apparent path of that follows the t = 0 line in that frame. (you can give it some small positive slope if you want, the effective result doesn't change.)
You had previously correctly stated the postulates of relativity. Per the first of those, the laws of physics are the same on the ship. As a result, a signal in the ship frame should also be able to travel to the star that goes nova following the t = 0 line in that frame.
...the Postulates of Special Relativity?
1. The laws of physics are the same in all inertial frames of reference.
2. The speed of light in vacuum has the same value c in all inertial frames of reference.
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Moving relative to everything we see around us. Our galaxy, the local group. Effectively the fabric of spacetime itself. We don't observe anything whizzing around at near luminal velocities. (At further scales it is space itself that is moving, not objects through space) For the velocities we observe, the Lorentz factor is close enough to 1 to be ignored.
But the ship is not stationary and Gamma is not 1. The ship witnessed the acceleration and knew quite well that it was not the entire universe around it suddenly accelerating to a large fraction of c.
The ship witnessed the apparent length contraction and knows it to be illusion of it's high relative velocity. It knows the entire galaxy did not suddenly shrink around it. The ship knows that when it slows back down, every star will appear to go back to where it was, after accounting for the ship's new position.
And the ship knows that whatever temporal shift appears to be happening according to the math is just the illusion of it's one clock running much slower than the billions of other clocks around it.
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Moving relative to everything we see around us. Our galaxy, the local group.
Which are all moving at different speeds in different directions and made up of individual things doing the same.
The first postulate that underlies all of special relativity:
All inertial reference frames are equivalent.
If you ignore this, there is no way to explain the constancy of the speed of light across reference frames.
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The message sent "to" that star is moving "toward" the star, not away from it. In the frame of the message, the space-time axis must rotate so as to approach the star, not move away from it as in the ship's frame. The paradox is caused by ignoring this 3rd reference frame of the message "approaching" the star.
IMO, I agree with the one statement in that paper I found, and that is; if we can't travel into the past while at rest or moving STL, then we can't do it moving FTL either, because all motion is relative.
Defining an FTL frame causes problems, so to work around that you can simply and validly just look at what happens in the STL inertial frames.
In the Earth frame, the ansible sends information from the nova to Earth travelling on an apparent path of that follows the t = 0 line in that frame. (you can give it some small positive slope if you want, the effective result doesn't change.)
You had previously correctly stated the postulates of relativity. Per the first of those, the laws of physics are the same on the ship. As a result, a signal in the ship frame should also be able to travel to the star that goes nova following the t = 0 line in that frame.
...the Postulates of Special Relativity?
1. The laws of physics are the same in all inertial frames of reference.
2. The speed of light in vacuum has the same value c in all inertial frames of reference.
In your previous post you said;
"The very foundation of relativity is that all inertial reference frames are equivalent. "
but the first postulate of relativity actually says;
"The laws of physics are the same in all inertial frames of reference."
These two statements are NOT the same thing. Your statement is an "assumption" of what you think it means, but I gave examples on page 6 of this thread, showing that we CAN have different inertial reference frames with different scaling parameters and still, "The laws of physics are the same in all inertial frames of reference.", regardless of how that frame is scaled.
So you see, there is a hidden assumption that if the laws of physics are the same, then the inertial reference frames are "equal", but my example proves that this is not necessarily true. We can have inertial reference frames that are not equal and have different scaling and still the laws of physics do not change.
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If we have a Gamma of 1, and the ship has a Gamma of 1.25, how are those equivalent? How do I ignore that a ship that has accelerated is pretending it did nothing of the sort?
All the factors you list explain the consistency of the speed of light. What they don't explain is how acceleration equals an actual time shift into the past that would cause an ansible communicated paradox.
An observer's state of motion cannot affect an observed object, but it can affect the observer's observations of the object.
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If we have a Gamma of 1, and the ship has a Gamma of 1.25, how are those equivalent? How do I ignore that a ship that has accelerated is pretending it did nothing of the sort?
All the factors you list explain the consistency of the speed of light. What they don't explain is how acceleration equals an actual time shift into the past that would cause an ansible communicated paradox.
An observer's state of motion cannot affect an observed object, but it can affect the observer's observations of the object.
Gamma is only defined in a relative sense between 2 frames, and it goes both ways.
The Earth's clocks are running slow by a factor of 1,25 according to the ship. Just as in the ship frame the 2 stars are only 4 light years apart, in the Earth frame, the length of the ship is shrunk by a factor of 4/5.
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But the two stars are actually 5ly apart.
Norm, I think statements like these are where you're going wrong. There are no "actual" lengths in relativity. There are only lengths measured in various reference frames. The same with time intervals.
The ship would know that from its charts.
No, the ship would only know that in another frame of reference the two stars are 5 ly apart. There is nothing special about the terrestrial frame of reference.
Similarly, there is no "actual" order of events. There are only order of events observed form various reference frames which, as others are telling you, do not necessarily agree. As long as signal speeds are restricted to light speed and lower this doesn't create any causality problems. But if we postulate faster than light signal speeds causality violations occur.
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But the two stars are actually 5ly apart.
Norm, I think statements like these are where you're going wrong. There are no "actual" lengths in relativity. There are only lengths measured in various reference frames. The same with time intervals.
The ship would know that from its charts.
No, the ship would only know that in another frame of reference the two stars are 5 ly apart. There is nothing special about the terrestrial frame of reference.
Similarly, there is no "actual" order of events. There are only order of events observed form various reference frames which, as others are telling you, do not necessarily agree. As long as signal speeds are restricted to light speed and lower this doesn't create any causality problems. But if we postulate faster than light signal speeds causality violations occur.
The "proper length" or distance is the distance between the two stars in the frame in which the observer is at rest relative to those stars. This distance is 5ly. All other frames moving relative to this frame will show a shorter distance between them. It is special because it is the "only" frame in which the stars have 5ly between them. The ship is not at rest relative to these stars, and the pilot should be smart enough to know that what he measures as the distance between those two stars is not the "proper distance".
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The "proper length" or distance is the distance between the two stars in the frame in which the observer is at rest relative to those stars. This distance is 5ly. All other frames moving relative to this frame will show a shorter distance between them. It is special because it is the "only" frame in which the stars have 5ly between them. The ship is not at rest relative to these stars, and the pilot should be smart enough to know that what he measures as the distance between those two stars is not the "proper distance".
Proper length is a concept that has limited utility. For example you can't define the current "proper distance" between the ship and one of the stars.
What you say does not change the facts of the distances measured in the ship frame.
In your previous post you said;
"The very foundation of relativity is that all inertial reference frames are equivalent. "
but the first postulate of relativity actually says;
"The laws of physics are the same in all inertial frames of reference."
These two statements are NOT the same thing.
The second statement is slightly more formal, but they do not mean anything different.
Your statement is an "assumption" of what you think it means, but I gave examples on page 6 of this thread, showing that we CAN have different inertial reference frames with different scaling parameters and still, "The laws of physics are the same in all inertial frames of reference.", regardless of how that frame is scaled.
If you are saying that there is a magic absolute "scale value" that is different in different inertial reference frames, you are breaking the first postulate. (Remember we are talking about flat spacetime where K is a constant.)
So you see, there is a hidden assumption that if the laws of physics are the same, then the inertial reference frames are "equal", but my example proves that this is not necessarily true. We can have inertial reference frames that are not equal and have different scaling and still the laws of physics do not change.
That is not a hidden assumption, but the explicit statement.
You did not prove what you said because either:
- K is the same in all inertial reference frames in flat spacetime (the "different scaling" is not true)
- K differs between inertial reference frames, which is a change in the laws of physics. (Besides the fact that you only showed that the value for force is unchanged, plenty of other values would be changed such as velocity and acceleration.)
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In your previous post you said;
"The very foundation of relativity is that all inertial reference frames are equivalent. "
but the first postulate of relativity actually says;
"The laws of physics are the same in all inertial frames of reference."
These two statements are NOT the same thing.
The second statement is slightly more formal, but they do not mean anything different.
I'm sorry, but this is where you are wrong. If K is constant and K =/= 1, there are no experiments you can do within that inertial frame that would demonstrate any violation of the laws of physics. Therefore the two statements do not mean the same thing at all. Two inertial frames that are not equivalent, does not violate any of the laws of physics in either frame. All experiments within an inertial frame will give identical results. I guarantee it, regardless of the relative value of K.
Your statement is an "assumption" of what you think it means, but I gave examples on page 6 of this thread, showing that we CAN have different inertial reference frames with different scaling parameters and still, "The laws of physics are the same in all inertial frames of reference.", regardless of how that frame is scaled.
If you are saying that there is a magic absolute "scale value" that is different in different inertial reference frames, you are breaking the first postulate. (Remember we are talking about flat spacetime where K is a constant.)
Nope. See above and while your at it, why don't you actually go back and read the posts I made on page 6 of this Thread, and review the references I posted on page 7 too. You need to learn something new and understand the math before you can prove me wrong, and obviously you haven't because you still think it's wrong.
So you see, there is a hidden assumption that if the laws of physics are the same, then the inertial reference frames are "equal", but my example proves that this is not necessarily true. We can have inertial reference frames that are not equal and have different scaling and still the laws of physics do not change.
That is not a hidden assumption, but the explicit statement.
You did not prove what you said because either:
- K is the same in all inertial reference frames in flat spacetime (the "different scaling" is not true)
- K differs between inertial reference frames, which is a change in the laws of physics. (Besides the fact that you only showed that the value for force is unchanged, plenty of other values would be changed such as velocity and acceleration.)
Case 3: K differs between inertial reference frames and it does NOT change the laws of physics by any experiment that can be done within said frame. The effect of different values of K is equivalent go a gauge transformation of the EM field. We all know, gauge transformations do not change the laws of physics. We also know that K is a variable in a gravitational field and EM fields are invariant in gravitational fields.
The relative value of K can ONLY be measured by a distant observer, comparing two different regions of space-time.
The EM ZPF is such that motion relative to the ZPF cannot be detected by any means. The vacuum does not exert forces on matter in motion. However, gravitational fields fill all space-time within our galaxy and motion relative to a gravitational field can be detected. I've said before and I'll say it again, our "local baseline" is the gravitational field of the Earth/Sun solar system. For any object that starts at rest on Earth, any motion relative to this frame will be physically length contracted and time dilated "relative to Earth". The reciprocal is due to the instruments in motion having been altered during acceleration to that speed, by the work done to them. There was no work done to the Earth that would cause this effect. Any such object can never go back in time relative to Earth-time, regardless of how fast it goes.
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However, gravitational fields fill all space-time within our galaxy and motion relative to a gravitational field can be detected. I've said before and I'll say it again, our "local baseline" is the gravitational field of the Earth/Sun solar system.
This highlights the main problem in this discussion, you simply insist on talking about curved spacetime, when the discussion is about essentially flat spacetime. We are not talking about local reference frames in general relativity where there is a measurable difference in gravitational potential between the 2 locations.
I did read your previous post (relevant part quoted below).
You showed that force would be unchanged, but ignored that velocity and acceleration would clearly be changed, therefore your logic is simply wrong.
Regarding the 1st postulate; using the dimensional conversions,
Mass M = M0*K3/2
Length L = L0/√K
Time T = T0*√K
Calculate how Forces depend on K. Simple;
Force = (Mass)*(Length)/(Time)2 = (M0*K3/2)*(L0/√K)/(T0*√K)2
So => M*L/T2 = M0*L0/T02
In other words, the forces we measure in experiments are completely independent of the local value of K. So all inertial reference frames will experience the same forces and have the same results to ALL experiments that verify SR and GR.
The relative value of K can ONLY be measured by a distant observer, comparing two different regions of space-time.
I think you are confused here, relative values don't need to be measured by a distant observer, as a practical example, we can measure the difference between the "Earth Ground" frame and the "GPS satellite" frame using the change in clock speed. The "distant observer" is used as a way to define an absolute scale.
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However, gravitational fields fill all space-time within our galaxy and motion relative to a gravitational field can be detected. I've said before and I'll say it again, our "local baseline" is the gravitational field of the Earth/Sun solar system.
This highlights the main problem in this discussion, you simply insist on talking about curved spacetime, when the discussion is about essentially flat spacetime. We are not talking about local reference frames in general relativity where there is a measurable difference in gravitational potential between the 2 locations.
I did read your previous post (relevant part quoted below).
You showed that force would be unchanged, but ignored that velocity and acceleration would clearly be changed, therefore your logic is simply wrong.
Regarding the 1st postulate; using the dimensional conversions,
Mass M = M0*K3/2
Length L = L0/√K
Time T = T0*√K
Calculate how Forces depend on K. Simple;
Force = (Mass)*(Length)/(Time)2 = (M0*K3/2)*(L0/√K)/(T0*√K)2
So => M*L/T2 = M0*L0/T02
In other words, the forces we measure in experiments are completely independent of the local value of K. So all inertial reference frames will experience the same forces and have the same results to ALL experiments that verify SR and GR.
The relative value of K can ONLY be measured by a distant observer, comparing two different regions of space-time.
I think you are confused here, relative values don't need to be measured by a distant observer, as a practical example, we can measure the difference between the "Earth Ground" frame and the "GPS satellite" frame using the change in clock speed. The "distant observer" is used as a way to define an absolute scale.
It's not wrong. The rulers and clocks in the "local" frame are scaled according to the value of "K" such that all observers in the inertial frame measure "c" for the speed of light, not c/K. To measure c/K it has to be done from a distant frame with a different value of K, using rulers and clocks that have not been normalized to the value of K to be measured.
True, the "distant observer" sets a baseline where there are no gravitational fields, where the gravitational potential is "0" and as such, the frame where gravitational potential is null is a preferred frame in this model. That in itself does not violate any laws of physics as you keep trying to claim. The laws of physics are still the same in all inertial frames, as can be shown by any experiment done in a local inertial frame. There is no way to measure the value of K locally.
c/K is the coordinate speed of light. That is all it represents. To have K=1 as an absolute value, we need coordinates that are far from gravitational fields. For any other value of K, "flat space-time", is simply where the derivatives of K vanish, just as the derivatives of the metric vanish. This does not require K=1, it could be K=1.5 or any other "constant" where the derivatives vanish.
Please read some of the reference I posted, such as Hal Puthoff's papers. This model has been around since 1957 or so and has been advanced mostly by Hal and myself, independently.
In this model, the fact that the speed of light is a constant to all inertial observers is a "result" of the fact that rulers and clocks are renormalized when the value of K in the local environment changes. If it were not for this quantum mechanical process, the value of c would not be constant to all local observers.
Please don't give me the old Usenet argument that "c" is constant because "it just is", and physicists do not ask "why?". I asked why, and I'm trying to convey what I learned. "c" is a constant because rulers and clocks are variables in space-time where matter is present.
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Time dilation is not an illusion, that is the only thing that is real. The gamma factor of relativistic travel is real and that is what separates the reference frames from each other. The Solar system and surrounding stars are moving at about 0.00075c. That is what separates our reference frame from that of a 0.6c ship.
Moving at 0.00075c or 0.6c relative to what? You seem to be assuming that there is some special reference frame, which is in contradiction with relativity.
Something that I've been wondering about is CMBR dipole anisotropy. Our galaxy is moving at about 622 km/s compared to the CMB. Since the CMB can be measured anywhere in the universe, doesn't that create a prefered frame?
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Nearly your entire post appears irrelevant. I think you missed the first thing I said in the last post.
This highlights the main problem in this discussion, you simply insist on talking about curved spacetime, when the discussion is about essentially flat spacetime. We are not talking about local reference frames in general relativity where there is a measurable difference in gravitational potential between the 2 locations.
I'll answer some of it just because some of it was already off topic in my previous post, and answering might help us get on the same page.
True, the "distant observer" sets a baseline where there are no gravitational fields, where the gravitational potential is "0" and as such, the frame where gravitational potential is null is a preferred frame in this model.
That seems to me an obvious part of GR, similar to EM where you have to put your potential reference somewhere and everything is easier if you do it for 0 potential at infinity. You seem to be missing something when you call this "the preferred frame." Maybe it was just a slip in language, but there are still an infinite number of these frames all with different relative velocities, and there is no way to define one as preferred over any other.
There is no way to measure the value of K locally.
You left off the word "relative" this time, so I think we can agree. (Tentative on me doing more research, but this is unimportant anyway, because we are only talking about flat spacetime.)
Now try answering this question:
In flat spacetime, there are 2 objects with a velocity relative to each other of 0.6c. Is K the same for the rest frame of each of these objects?
If not, how would the distant observer (who can basically be right next to the objects because flat space time) tell what the difference is?
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Time dilation is not an illusion, that is the only thing that is real. The gamma factor of relativistic travel is real and that is what separates the reference frames from each other. The Solar system and surrounding stars are moving at about 0.00075c. That is what separates our reference frame from that of a 0.6c ship.
Moving at 0.00075c or 0.6c relative to what? You seem to be assuming that there is some special reference frame, which is in contradiction with relativity.
Something that I've been wondering about is CMBR dipole anisotropy. Our galaxy is moving at about 622 km/s compared to the CMB. Since the CMB can be measured anywhere in the universe, doesn't that create a prefered frame?
Yes.
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Something that I've been wondering about is CMBR dipole anisotropy. Our galaxy is moving at about 622 km/s compared to the CMB. Since the CMB can be measured anywhere in the universe, doesn't that create a prefered frame?
I want to talk about this too. I'm a bit afraid that in doing so it will get tangled in debates on basic relativity. Im not using "basic relativity" in a derogatory sense because I know I haven't personally mastered it. I would prefer to stick to the textbook pronouncements and not try to convince anyone who disputes them. There will always be someone in the conversation better qualified to do that.
This "CMB rest frame as special" is IMO the best solution so far. I have pasted it into the OP so that it doesn't get drowned in the basic relativity discussion.
I also made a point that I think this is equivalent to defining "simultaneous" as an isosurface though space-time where the CMB is a specific temperature. (you can also find this pasted into the OP).
The thing I wanted to add was, the CMB rest frame choice isn't merely nice. I think it is special because I think it almost rules out any other choice.. if you are going to chose some frame and label it special it pretty much has to be this one.
Why? because you are either choosing the ONLY definition of "instantaneous" where you are travelling between points of the universe that have the same temperature and entropy, and look pretty similar, or you are choosing ANY OTHER one where travel in one specific arbitrary direction takes you to a younger, hotter universe, and the other direction takes you to a colder one, even though the universe does not look hotter or colder in either of those directions. Only one choice of reference frame is nice, all the others are "yuck". Apart from being "yuck", there are probably horrible exploits you could implement if you could slide freely between entire observable universes at different states of entropy. IMO that makes one choice head and shoulders above an other possible one.
Bear in mind this does not override any laws of relativity. Like entropy itself, it is not really required by any of the other laws, which are all reversible. Yet we still live in a universe where change in entropy is perhaps the most important feature.
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The way you describe it, it seems like an obvious hypothesis. At least to a layman such as myself, assigning the cosmic microwave background this function has appeal as something akin to a "god's-eye view" of the universe that takes in everything at once. Most likely it is still wrong since I don't know of any scientists who espouse the hypothesis. But that doesn't matter as long as it serves as a good backstop for sci-fi that makes a good-faith effort to incorporate known natural law as well as logic.
Have any of the well-known authors of hard sci-fi (like, say, Greg Egan) built worlds based on the hypothesis yet?
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There is no way to measure the value of K locally.
You left off the word "relative" this time, so I think we can agree. (Tentative on me doing more research, but this is unimportant anyway, because we are only talking about flat spacetime.)
Now try answering this question:
In flat spacetime, there are 2 objects with a velocity relative to each other of 0.6c. Is K the same for the rest frame of each of these objects?
If not, how would the distant observer (who can basically be right next to the objects because flat space time) tell what the difference is?
In both cases, it would be impossible to tell from just the objects. In order to do anything, each object would need to be radiating a known frequency and wavelength, such as the Hydrogen absorption spectrum, or other known spectral sources. As well has having a well defined intensity amplitude, (a standard candle) so that they can be compared with enough detail to determine what red/blue shift is due to K and what red/blue shift is due to relative motion.
The terms, (v/c)2 and K are not simply interchangeable. The derivation of Gamma as a function of K yields;
γ(v,K) = 1/√((1/K) - K*(v/c)2)
Also, what you refer to as flat space-time and what I refer to as flat space-time are not the same. To have length contraction and time dilation requires more than just a vacuum. It requires quantum vacuum fluctuations and power dissipation. Neither GR or SR require this, although it is there if you formulate the correct problem and know where to look. That is why these are classical theories, where mine is a quantum theory.
In Relativity, all vacuum is the same. In QED, all vacuums are not the same.
Flat space-time:
Start with the massless particles, (Bosons), EM field photons, Strong field gluons and fill the entire universe with their minimum energy state, the Zero-point fields (ZPF)'s.
Add to this massive particles, (Fermions) the Dirac field, the electron family, the quark family, etc.. and their ZPF's.
Add to this EM, weak and strong forces acting on the particles and particles acting on the fields.
Add to this the CMB radiation field and all the long range fields that span the universe.
Add to this the interaction between the Bosons and the Fermions, such as; spontaneous absorption, spontaneous emission and stimulated emission rates; EM momentum, angular momentum, etc.. until all fields establish a steady state equilibrium "state" that we define as |vac>.
Up to this point, space-time is still "flat". We haven't even added atoms, solids, liquids or gases yet. This is just the Minimum Energy state of the vacuum. If we do not take these things into consideration, then we are not talking about a realistic situation and the idea of Time Travel is pure speculation.
Fact: we cannot measure velocity relative to a ZPF (or multiples there-of). However, we can measure our velocity relative to the other stuff that is superimposed upon it, such as the CMBR. As of yet, there is no evidence that motion relative to the CMBR has any effect at all. However, I don't think it's been tested yet either.
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Now try answering this question:
In flat spacetime, there are 2 objects with a velocity relative to each other of 0.6c. Is K the same for the rest frame of each of these objects?
If not, how would the distant observer (who can basically be right next to the objects because flat space time) tell what the difference is?
There's time's arrow, and then there's mass. Which object accelerated, which one didn't? Which is more massive? If a tiny ship and an entire galaxy are both observed, it's pretty easy to tell which one is moving. Especially if the galaxy isn't moving at sublight relative to neighboring galaxies.
Reference frames can appear exactly the same at steady state, but they have histories and memories and are not the same. One is real, one is transitory.
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Something that I've been wondering about is CMBR dipole anisotropy. Our galaxy is moving at about 622 km/s compared to the CMB. Since the CMB can be measured anywhere in the universe, doesn't that create a prefered frame?
I want to talk about this too. I'm a bit afraid that in doing so it will get tangled in debates on basic relativity. Im not using "basic relativity" in a derogatory sense because I know I haven't personally mastered it. I would prefer to stick to the textbook pronouncements and not try to convince anyone who disputes them. There will always be someone in the conversation better qualified to do that.
This "CMB rest frame as special" is IMO the best solution so far. I have pasted it into the OP so that it doesn't get drowned in the basic relativity discussion.
I also made a point that I think this is equivalent to defining "simultaneous" as an isosurface though space-time where the CMB is a specific temperature. (you can also find this pasted into the OP).
The thing I wanted to add was, the CMB rest frame choice isn't merely nice. I think it is special because I think it almost rules out any other choice.. if you are going to chose some frame and label it special it pretty much has to be this one.
Why? because you are either choosing the ONLY definition of "instantaneous" where you are travelling between points of the universe that have the same temperature and entropy, and look pretty similar, or you are choosing ANY OTHER one where travel in one specific arbitrary direction takes you to a younger, hotter universe, and the other direction takes you to a colder one, even though the universe does not look hotter or colder in either of those directions. Only one choice of reference frame is nice, all the others are "yuck". Apart from being "yuck", there are probably horrible exploits you could implement if you could slide freely between entire observable universes at different states of entropy. IMO that makes one choice head and shoulders above an other possible one.
Bear in mind this does not override any laws of relativity. Like entropy itself, it is not really required by any of the other laws, which are all reversible. Yet we still live in a universe where change in entropy is perhaps the most important feature.
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As of yet, there is no evidence that motion relative to the CMBR has any effect at all. However, I don't think it's been tested yet either.
Source:
In reality, however, not all directions in the sky appear to have the same CMB brightness. The earth is moving with respect to the matter that last emitted the CMB, and therefore the CMB spectrum looks bluest (and, by Wien's law, therefore hottest) in that direction and reddest (and coolest) opposite to that direction.
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If the dipole contribution due to Earth's motion is now subtracted out, the sky looks like the figure at the left.
Indicates motion relative to the CMB. They subtract out the effect of that motion to observe the CMB.
In regards to the bold text, I named off one exploit earlier which is a conservation of energy violation if one retains momentum while transporting back in time. Repetedly teleport your self away from a gravitational well over and over again and you have a paradox.
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Most likely it is still wrong since I don't know of any scientists who espouse the hypothesis. But that doesn't matter as long as it serves as a good backstop for sci-fi that makes a good-faith effort to incorporate known natural law as well as logic.
Can't really hope for more :)
Have any of the well-known authors of hard sci-fi (like, say, Greg Egan) built worlds based on the hypothesis yet?
I haven't encountered it. At least not the temperature-based resolution. Nothing actually points to it being real. That would be outside the scope of this thread anyway.
It could start an interesting conversation about what is the difference between a fundamental rule of physics and what is just situation. Ants might think the ground plane of the earth is a fundamental reference frame of the universe that everything can be measured against. The big bang, and every principle resulting from entropy such as the arrow of time, might be just a situation. Maybe every fundamental rule becomes just a situation from some higher vantage point. (edit: In fact if this isn't the case explaining the universe becomes a lot more tricky. Several constants are fine tuned for life and the easiest explanation is that they take on a range of values across some infinite set of universes and we only see the one of the few permutations where life is possible)
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Now try answering this question:
In flat spacetime, there are 2 objects with a velocity relative to each other of 0.6c. Is K the same for the rest frame of each of these objects?
If not, how would the distant observer (who can basically be right next to the objects because flat space time) tell what the difference is?
There's time's arrow, and then there's mass. Which object accelerated, which one didn't? Which is more massive? If a tiny ship and an entire galaxy are both observed, it's pretty easy to tell which one is moving. Especially if the galaxy isn't moving at sublight relative to neighboring galaxies.
Reference frames can appear exactly the same at steady state, but they have histories and memories and are not the same. One is real, one is transitory.
What magic keeps track of the "history" of any given object? What is the measurable effect that this has?
"if the galaxy isn't moving at sublight" You apparently have not understood a single word of anything you have read about relativity if you think an entire galaxy moving at FTL makes any sense.
I could be misreading something here, but it seems to me like you have newly come to the subject of relativity, and found that it doesn't fit with your intuition. Rather than recognize that your intuition might be wrong (basically everyone's is at first), you are now making up nonsensical rules without even considering their inconsistency with experimental results or themselves.
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In both cases, it would be impossible to tell from just the objects. In order to do anything, each object would need to be radiating a known frequency and wavelength, such as the Hydrogen absorption spectrum, or other known spectral sources. As well has having a well defined intensity amplitude, (a standard candle) so that they can be compared with enough detail to determine what red/blue shift is due to K and what red/blue shift is due to relative motion.
Sure, attach whatever specialized light bulb/ related equipment you need, assume both ships have advanced on board labs with lasers or any other measuring equipment you want. If you are really concerned with calibration, have an ultra high acceleration shuttle pass between them when they get near each other.
In this model, the fact that the speed of light is a constant to all inertial observers is a "result" of the fact that rulers and clocks are renormalized when the value of K in the local environment changes. If it were not for this quantum mechanical process, the value of c would not be constant to all local observers.
To have length contraction and time dilation requires more than just a vacuum. It requires quantum vacuum fluctuations and power dissipation. Neither GR or SR require this, although it is there if you formulate the correct problem and know where to look. That is why these are classical theories, where mine is a quantum theory.
In Relativity, all vacuum is the same. In QED, all vacuums are not the same.
In QED, guess what: all vacuums are the same. One reason this can be said is simply that QED by definition includes special relativity, and the same rules carry over. This is needed at this level of merging theories because the full form of electrodynamics has special relativity built in from before Einstein even came up with special relativity.
Flat space-time:
Start with the massless particles, (Bosons), EM field photons, Strong field gluons and fill the entire universe with their minimum energy state, the Zero-point fields (ZPF)'s.
Add to this massive particles, (Fermions) the Dirac field, the electron family, the quark family, etc.. and their ZPF's.
Add to this EM, weak and strong forces acting on the particles and particles acting on the fields.
Add to this the CMB radiation field and all the long range fields that span the universe.
And hold it right there. CMB is already covered by "EM fields" and it also consists of you adding energy to these fields above the vacuum state. Also some of what you said sounded like adding the particles themselves, and not just the corresponding ZPFs. You also seemed to have listed "bosons" as massless, even though bosons are not generally massless (even if you only count the fundamental ones).
As of yet, there is no evidence that motion relative to the CMBR has any effect at all. However, I don't think it's been tested yet either.
It is the kind of thing that would be noticed in things like the Michelson-Morley experiment, various replications and similar experiments, or just plain anomalies in things like particle accelerators.
Just to share with you my current perspective:
- From discussing the "twin paradox" (which I will always put in quotes because it isn't a paradox) I was able to point out where your explanation of what happens became contradictory. This really isn't a complicated part of special relativity, and your initial lack of understanding shows that you had been thinking about relativity incorrectly.
-This does not seem to have prompted you to reconsider the rest of your theory.
-You now are starting to touch on quantum mechanics, the most complicated, confusing and frequently misunderstood part of modern physics.
-You made some apparently unfounded statements related to quantum including one that flat out contradicts what we consider to be true about the quantum vacuum.
-You made clear mistakes in what should have been a simple list of elementary particles.
You are on the way to convincing me that despite some appearances to the contrary you might not have the slightest clue what you are talking about.
Take a few steps back, and rather than trying to discuss the theory of everything that Einstein and basically every physicist since has been in search of, start with simple cases, and add complications from there. So back to those 2 object moving relative to each other in flat spacetime: Explain exactly how their K values, relative or absolute, could be measured.
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What magic keeps track of the "history" of any given object? What is the measurable effect that this has?
"if the galaxy isn't moving at sublight" You apparently have not understood a single word of anything you have read about relativity if you think an entire galaxy moving at FTL makes any sense.
First, "sublight" isn't FTL. I meant moving at a large fraction of c, like 0.6c. Sorry to confuse.
You asked how a distant observer could tell two reference frames apart. A history of observation is one way. I said two reference frames at steady state could be mathematically equivalent. But a ship that just accelerated and a galaxy that didn't are different. They can be distinguished.
Next is mass (or energy state). An observer sees a small ship and an entire galaxy. Yes it is nonsensical for the ship to be stationary and the entire galaxy to be moving at 0.6c. (Especially when the galaxy isn't moving at that speed relative to other galaxies). The object with the largest mass and lowest energy state is the rest frame. The ship moves through the galaxy, not the other way around. Proper length between stars is defined by that frame.
In completely flat empty nothing then yes an observer can't tell if it's the ship or the galaxy moving. But our universe is not flat and empty. It has structure. Structure on massive scales.
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You asked how a distant observer could tell two reference frames apart. A history of observation is one way. I said two reference frames at steady state could be mathematically equivalent. But a ship that just accelerated and a galaxy that didn't are different. They can be distinguished.
History of observation is irrelevant, unless there is something physically measurably different about them now, history doesn't matter.
Your apparent claim that matter that accelerated and matter that didn't are distinguishable is nonsensical and contrary to everything we know about the universe. Every single piece of matter has been demonstrated to have the exact same physical properties regardless of their history. Every "difference" in results of an experiment in moving matter (like Doppler shift of an emission line) is symmetric where stationary matter and moving equipment would get the exact same result.
Next is mass (or energy state). An observer sees a small ship and an entire galaxy. Yes it is nonsensical for the ship to be stationary and the entire galaxy to be moving at 0.6c. (Especially when the galaxy isn't moving at that speed relative to other galaxies). The object with the largest mass and lowest energy state is the rest frame.
Why? This might be a convenient frame to use, but it is NOT special. You insisting it must be indicates you have not actually allowed yourself to understand even the most basic concept in relativity.
In completely flat empty nothing then yes an observer can't tell if it's the ship or the galaxy moving. But our universe is not flat and empty. It has structure. Structure on massive scales.
The whole point of relativity is that if you consider all of that "structure" to be moving and a tiny ship to be sitting still, physics doesn't change.
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Maybe we're using a different definition of "distinguish"? You asked how a distant observer can tell the difference between two reference frames. Well, they have different mass, don't they? That is a difference that can be "distinguished".
I didn't say the laws of physics are different between two reference frames. I accept that all the math is exactly the same for the ship and the galaxy. And that when the ship accelerates, it may actually be slowing down to a dead stop (relative to what though?) while the rest of the universe flies by. But acceleration acts on one reference frame and not another. I don't get to Centauri by sitting still and demanding the universe accelerate towards me.
Our galaxy is moving towards the Large Attractor at about 0.0033c which is not relativistic. That whole structure defines a single reference frame. And yes it is "special" as it's incredibly massive and there isn't another one anywhere else in this corner of the universe. Not special in terms of physics. Special in terms of mass and being the one common frame of reference.
So now, according to our big massive common reference frame, our two stars are 5ly apart and everyone agrees on that. Our ship accelerates to 0.6c and the two stars are observed to be 4ly apart. All the math works (because ship clock is running slow). But the stars did not move 1ly closer together in the big massive common reference frame. They did not move relative to the reference frame, the ship did.
An observer's state of motion cannot affect an observed object, but it can affect the observer's observations of the object.
The big massive frame of reference defines our reality. The stars are 5ly apart in our reality. A relativistic ship doesn't change that, and doesn't move the nova event 7.5 years into the future. That is only what the ship observes. As real as it is mathematically, it is not real in our physical reality where we are bound to this reference frame.
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Maybe we're using a different definition of "distinguish"? You asked how a distant observer can tell the difference between two reference frames. Well, they have different mass, don't they? That is a difference that can be "distinguished".
I didn't say the laws of physics are different between two reference frames. I accept that all the math is exactly the same for the ship and the galaxy. And that when the ship accelerates, it may actually be slowing down to a dead stop (relative to what though?) while the rest of the universe flies by. But acceleration acts on one reference frame and not another. I don't get to Centauri by sitting still and demanding the universe accelerate towards me.
Our galaxy is moving towards the Large Attractor at about 0.0033c which is not relativistic. That whole structure defines a single reference frame. And yes it is "special" as it's incredibly massive and there isn't another one anywhere else in this corner of the universe. Not special in terms of physics. Special in terms of mass and being the one common frame of reference.
So now, according to our big massive common reference frame, our two stars are 5ly apart and everyone agrees on that. Our ship accelerates to 0.6c and the two stars are observed to be 4ly apart. All the math works (because ship clock is running slow). But the stars did not move 1ly closer together in the big massive common reference frame. They did not move relative to the reference frame, the ship did.
An observer's state of motion cannot affect an observed object, but it can affect the observer's observations of the object.
The big massive frame of reference defines our reality. The stars are 5ly apart in our reality. A relativistic ship doesn't change that, and doesn't move the nova event 7.5 years into the future. That is only what the ship observes. As real as it is mathematically, it is not real in our physical reality where we are bound to this reference frame.
So do you admit that you do not accept Einstein's theory of relativity?
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I didn't say the laws of physics are different between two reference frames. I accept that all the math is exactly the same for the ship and the galaxy.
If you accept that the laws of physics are the same in all reference frames, then when proposing FTL/ansibles, you cannot argue that FTL has to be measured relative to any given frame, or that all ansibles only communicate instantaneously according to a special frame.
Also, relativistic effects would clearly be noticeable at 0.0033c , it means gamma of 1.0000054, and that kind of experimental sensitivity is decently common. Also, when combined with interstellar distances, it is plenty to create a scenario where an ansible allows time travel. As I pointed out earlier in this thread, Earth's orbital velocity around the sun and 10 light years is enough.
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I haven't decided yet. I'm agnostic and not ready to accept every aspect of Relativity with all my heart. Notably the time axis shift that creates the paradox. But I seem to be upsetting people so I think I'll just stop here.
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I haven't decided yet. I'm agnostic and not ready to accept every aspect of Relativity with all my heart. Notably the time axis shift that creates the paradox. But I seem to be upsetting people so I think I'll just stop here.
Thanks. I happen to agree with almost everything you've said. Your intuition is spot-on. As for me, I would ask @as58 and @meberbs;
Why is "c" constant to all inertial observers, regardless of their relative motion?
If they have an answer other than "it just is", then they will have to reconcile the same points that we have been trying to make. Acceleration, and work done to matter, does in fact alter time and length "for that object". Expanding space is isomorphic to a contracting ruler, and time dilation is isomorphic to harmonic oscillators losing energy to power dissipation.
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Thanks. I happen to agree with almost everything you've said. Your intuition is spot-on. As for me, I would ask @as58 and @meberbs;
Why is "c" constant to all inertial observers, regardless of their relative motion?
c being constant leads to a mathematically beautiful theory, though that is of course a matter of opinion.
However, special (and general, though that's not relevant here) relativity has also survived very stringent experimental tests and there's been no sign of any violation.
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Why is "c" constant to all inertial observers, regardless of their relative motion?
"Why" can be used to mean a lot of things, ultimately if you ask why enough times, you get down to "That is how God made the universe" (or an agnostic equivalent.)
At some point before that you could instead say something more along the lines of "The speed of light is a fundamental constant of the universe tied to the strength of electromagnetic forces, and because the laws of physics are the same in all inertial frames, the speed of light also must be a constant." There are many variations on this possible, because the laws of physics are like a puzzle where all the pieces fit together, and there is more than one set of starting conditions you can use to derive the rest.
I think what you are trying to ask is more along the lines of "what physical mechanism allows the speed of light to be constant in different reference frames." The answer to that is clearly time dilation and length contraction.
There is no reconciliation that needs to be done about acceleration altering the rulers and clock on an object, because the resulting behavior once the acceleration is done does not depend in any way on the original speed, or the rate or path of acceleration. Any claim otherwise would imply that 2 objects right next to each other travelling at the same speed would have their clocks in disagreement (i.e. ticking at different rates). (Remember flat space-time so there are no nearby significant gravity wells)
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I have no issues with c being constant locally while at the same time c "not" being constant non-locally. Basically for space in a gravitational well the plank length contracts and time slows while c slows non-locally. Locally everything remains constant and physics remains preserved.
In a gravitational well if we length contract the plank length of space - imagine some cubes of space where near a gravitational well these cubes contract in length. This forces a curvature on space because of the change in size. For c to remain constant in that cube with the contracted length, c non-locally must slow down.
For a ship accelerating that ship must absorb energy. That energy becomes effective mass. It's space and time axis tilts towards the light cone. The universe does not gain this energy. The universe which didn't accelerate experiences no change in the tilt of its space and time axis, nor the change in temperature of the CMBR, nor does it show signs of slowing its aging via the space time axis tilt (twin paradox). Those aboard the ship observe the change in temperature of the CMBR, and the unvierse as pancaked in one axis, having a tilted time and space axis they physically travel through time slowing their aging. The ship which reaches near c is the one with the tilted time/space axis and not the universe
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Why then do those aboard the ship observe the universe as having a tilted time/space axis? Because this unvierse/CMBR is their tilted time/space frame. The universe observes the ships local frame as tilted - not its frame. There is no disagreement between them.
There are two effects of time travel. time effect # 1 is time physically slowing down which goes hand in hand with the plank length contracting. This happens to the ship accelerating, and from the ships perspective the universe but this just preserves c in all frames.
Time effect # 2 is that what is length contracted via dt=gamma(t-v*dx/c^2) equation was missing c^2 at the very end determines whose local frame is being distorted in time, and who will live longer (who is the time traveler). This is where with distance dx and velocity v change in time increases with distance which is responsible for the length contraction. The universe does not time travel through its frame but the ship does.
This ship is always stuck traveling forwards so always forwards in time (the future) preserving the travelers life time.
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Hi, new question..
..if we go with the "CMB rest frame as special" solution to allow FTL, or (I think equivalently) define "instantaneous" as travel to another point that has the same CMB temperature..
Then what is the most ugly, weird, or counterintuitive phenomenon that we could encounter in such a universe?
I believe we can see the order of cause and effect being reversed in our own frame, if different from the CMB rest frame, but not in a way that allows grandfather paradoxes.
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"what physical mechanism allows the speed of light to be constant in different reference frames." The answer to that is clearly time dilation and length contraction.
Sorry, I have one more question. Time dilation and length contraction don't create the FTL paradox, so c being constant in all frames isn't the issue. It's the time axis shift and the concept that different velocities (with the exact same physics) give a different now for the exact same event.
Has that been experimentally confirmed to be real, and not just observation? Or is it still mathematical theory, but this isn't an ala carte menu?
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..if we go with the "CMB rest frame as special" solution to allow FTL, or (I think equivalently) define "instantaneous" as travel to another point that has the same CMB temperature..
Then what is the most ugly, weird, or counterintuitive phenomenon that we could encounter in such a universe?
First you would have to define what you mean by "special." In general, it means the principle of relativity is not true, so none of the results of special relativity would be valid. No time dilation, speed of light is relative to the rest frame, etc.
You could try to imagine a universe where the only thing special about the CMB frame is that FTL speeds are restricted relative to it, and otherwise the principle of relativity holds. Such FTL drives would have to be powered by a completely new, unknown law of physics that is the one exception to the principle of relativity. (And no, GR is not an exception to the principle of relativity, it is an extension of it) I do not know where to even begin formalizing such a theory, and we currently have no evidence of any such effects.
"what physical mechanism allows the speed of light to be constant in different reference frames." The answer to that is clearly time dilation and length contraction.
Sorry, I have one more question. Time dilation and length contraction don't create the FTL paradox, so c being constant in all frames isn't the issue. It's the time axis shift and the concept that different velocities (with the exact same physics) give a different now for the exact same event.
Has that been experimentally confirmed to be real, and not just observation? Or is it still mathematical theory, but this isn't an ala carte menu?
It is the last option (although there may be some specific experiment that clearly depends on it, and I am just not aware of). It is all one package, the math describing time dilation and length contraction also needs the time axis shift to describe a consistent universe. All of these are not separate effects, but just one (Lorentz transformation) that we conceptually break down its effects to wrap our heads around easier. Given that time dilation occurs symmetrically for both someone on Earth and someone travelling relative to Earth, the only way to consistently describe the situation from the "twin paradox" is to recognize the rotation of the travelling twin's time axis when they do their u-turn.
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..if we go with the "CMB rest frame as special" solution to allow FTL, or (I think equivalently) define "instantaneous" as travel to another point that has the same CMB temperature..
Then what is the most ugly, weird, or counterintuitive phenomenon that we could encounter in such a universe?
First you would have to define what you mean by "special." In general, it means the principle of relativity is not true, so none of the results of special relativity would be valid. No time dilation, speed of light is relative to the rest frame, etc.
You could try to imagine a universe where the only thing special about the CMB frame is that FTL speeds are restricted relative to it, and otherwise the principle of relativity holds. Such FTL drives would have to be powered by a completely new, unknown law of physics that is the one exception to the principle of relativity. (And no, GR is not an exception to the principle of relativity, it is an extension of it) I do not know where to even begin formalizing such a theory, and we currently have no evidence of any such effects.
That last option is what I mean. Maybe wormholes are real but they are closed by firewalls of infinite energy if you try to connect two points where the universe is in a different state of entropy. Maybe we live in a simulation. Whatever.
Im not aware of anything pointing to this being real, and it would be entirely above my abilities to argue it if it was.
Im just talking about problems like paradoxes, and failing that, ugly things like perpetual motion machines and non-conservation of momentum etc.
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"Einstein's 1905 theory is referred to as the "special" theory because it is limited to bodies moving in the absence of a gravitational field."
I found this on http://archive.ncsa.illinois.edu/Cyberia/NumRel/SpecialRel.html (http://archive.ncsa.illinois.edu/Cyberia/NumRel/SpecialRel.html) and similar statements elsewhere.
Does everyone agree with this statement? That SR is "Special" because of the absence of a gravitational field?
If so, this is why I reject SR in favor of GR and why we argue about a special reference frame. SR is an approximation where, in GR we assume that a small patch of space-time tangential to the curvature, can be considered an "inertial frame". This has been referred to as a "local inertial tangent plane" back when I learned it, and this is where SR is applicable within GR; "locally".
The key words here are "small patch", "local" and "approximation". The tangent plane is only flat over a short distance, compared to the curvature of the gravitational field. When we discuss this FTL paradox, we need very large distances that are presumed to be "flat". This is inconsistent with the idea of a "local" inertial tangent plane and seems to require a globally flat space-time.
What Norm38 and I have been saying, is not that there is a special reference frame, but that length contraction and time dilation are caused by the gravitational field, AND motion relative "to it". In the sense that, inside a gravity well time and the speed of light, are slower than outside it. Where the object starts from "rest", is in a gravity well of "something". Any acceleration from that location is "relative" to that location within the overall gravity well. So the special reference frame is not the CMBR and is not universal. Instead, it's the gravitational field that the "ship" interacts with that gives us a background reference frame for FTL, but it's still relative to other gravity wells. (i.e., galaxy, solar system, planet.)
I wonder... have there really not been any experiments done in flat space-time, only in approximations thereof?
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I haven't decided yet. I'm agnostic and not ready to accept every aspect of Relativity with all my heart. Notably the time axis shift that creates the paradox. But I seem to be upsetting people so I think I'll just stop here.
This is not up to accepting or not accepting. It has passed all tests and most or all predictions coming from it were confirmed.
To better understand the SPEED OF CAUSALITY, watch the video below. Specially the part about the electric monkey over the pony and the strenght of the magnetic field.
Without relativity, you can't decide the strenght of the magnetic field, it will be different for each observer. A stationary observer will add the speeds of the monkey over the pony plus the pony.
But from the pony point of view, he will get a different strenght, based on his stationary point of view with only the monkey moving over him.
https://www.youtube.com/watch?v=msVuCEs8Ydo
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Parasitic reactance between reference frames? Dissipation, entropy to lower energy states, based on mass. Quantum mechanics. Dark energy?
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Parasitic reactance between reference frames? Dissipation, entropy to lower energy states, based on mass. Quantum mechanics. Dark energy?
Yep. Have you read my paper from the Estes Park conference?
https://www.researchgate.net/publication/305501551_AN_ENGINEERING_MODEL_OF_QUANTUM_GRAVITY (https://www.researchgate.net/publication/305501551_AN_ENGINEERING_MODEL_OF_QUANTUM_GRAVITY)
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The key words here are "small patch", "local" and "approximation". The tangent plane is only flat over a short distance, compared to the curvature of the gravitational field. When we discuss this FTL paradox, we need very large distances that are presumed to be "flat". This is inconsistent with the idea of a "local" inertial tangent plane and seems to require a globally flat space-time.
Maybe you aren't aware of this, but all of those words you put in quotes are concepts that can be quantified, and given the strength of gravity and the distances between stars, distances of light years can be treated as flat in our universe. If you think otherwise you will have to show: 1. That interstellar space is not flat to a reasonable degree of accuracy. 2. That this non-flatness somehow leads to completely different results from special relativity (when in the flat case general relativity IS special relativity) 3. That specifically the general ways of producing time travel are in all cases prevented by this.
Note the need for #3 beyond #2 is because just "General relativity predicts things SR doesn't" doesn't invalidate the ways that FTL in SR produces time travel, it makes the math many times harder, but the SR effects are still present in GR, so it is hard to believe that the result of FTL = time travel would suddenly go away.
What Norm38 and I have been saying,
Actually, it seems to me that Norm38 has been saying fairly different things from you. He has been questioning some basic aspects of relativity including some that you have clearly recognized as necessary. Norm 38 has not gotten to the point where he would be discussing the effects of gravitational fields on time dilation, his posts were clearly at a higher level. You thinking that Norm38 is advocating the same viewpoint as you is one more thing on the list making me question "do you really know what you are talking about" Although in this case I think it is more of a natural human reaction of wanting someone else to be agreeing with you and unconsciously filtering their words so that you think that is the case.
Any acceleration from that location is "relative" to that location within the overall gravity well. So the special reference frame is not the CMBR and is not universal. Instead, it's the gravitational field that the "ship" interacts with that gives us a background reference frame for FTL, but it's still relative to other gravity wells. (i.e., galaxy, solar system, planet.)
When you make these statements, it seems that you are making an implicit assumption that objects somehow remember the history of what gravity well they previously had been in. In reality it really doesn't make much sense to think this matters, because their rulers and clocks should always sync up with someone local and moving with the same velocity, even if their histories were different.
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Any acceleration from that location is "relative" to that location within the overall gravity well. So the special reference frame is not the CMBR and is not universal. Instead, it's the gravitational field that the "ship" interacts with that gives us a background reference frame for FTL, but it's still relative to other gravity wells. (i.e., galaxy, solar system, planet.)
When you make these statements, it seems that you are making an implicit assumption that objects somehow remember the history of what gravity well they previously had been in. In reality it really doesn't make much sense to think this matters, because their rulers and clocks should always sync up with someone local and moving with the same velocity, even if their histories were different.
I concede that, given the STR and the Lorentz Transformations, the STR leads to a paradox for FTL. However, IMO it is ridiculous to use a theory based on a constant speed of light to discuss FTL travel in the first place. A variable speed of light (VSL) model would be more appropriate. Such a model is the Polarizable Vacuum Model of General Relativity, where the coordinate speed of light is used in the coordinates of a distant observer, c/K. I keep trying to bring this into the conversation and you keep kicking us back to SR and LT's. So let me try one last time.
First, there is no "memory". You are misinterpreting my words. To resolve this, I will explain it differently. Instead of a Minkowski background, let's start out with a Schwarzschild time-independent background metric for space-time. In the Schwarzschild background (SB), a null geodesic (light) has a coordinate speed;
ds2 = c2dt2/K - K*dr2 = 0
dr/dt = c/K
dr = dr0/√K
dt = dt0*√K
It is the gravitational potential that causes gravitational length contraction and time dilation for K > 1. The Schwarzschild solution is;
K = 1/(1 - 2GM/r*c2)
Since I don't think intergalactic travel will be possible anytime soon, let's stick to interstellar, within our own galaxy. The Milky Way has a supermassive black hole at it's center, and a lot of mass near the center that increases the gravitational potential at our solar system, relative to the center of gravity, (CoG) of the galaxy.
To summarize, all matter in the galaxy is immersed in a background gravitational field that sets the "base line" for length contraction and time dilation as variables, between r = ∞ and the event horizon of the BH, r = Rs.
Now, we turn on "time" so that the model is no longer time-independent and let things move. Any motion is relative to the CoG of the galaxy. Any object that accelerates to a high velocity such as 0.6c, has increased its total Energy, and therefore its potential energy relative to the CoG. As such, time dilation and length contraction increases "relative" to the base line position it started from. Any other object (with negligible rest mass) that is also moving at that speed and location, will be at the same gravitational potential and therefore has the same scaling of time and distance.
In this model, we can draw a Minkowski diagram at r=∞, and as r→Rs the space axis contracts and the time axis gets longer, per the equations above. The light cones get narrower. However, at any value of r, say rh we can renormalize the diagram so our light cone is 45-deg again, per our local measurements. Using this chart, looking at events where r>rh, it will appear that it is the space axis which is longer and the time axis that is shorter. The light cone will be flatter and FTL relative to rh, is observable. Consider hovering near the event horizon and looking up. It will appear that the rest of the galaxy is in Fast Forward.
In this formulation, there is never an opportunity to go backwards in time. There is no paradox and it is more "realistic" than the STR. Now, we could take a Machian/Woodward view, where in flat space-time an object still has a gravitational potential relative to the distant stars. In which case, the same argument applies. Any change in the relative energy of an object changes it's gravitational potential energy relative to the distant stars. However, STR is the special case where there is no gravitational field. Hence, it is not applicable in this model.
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A variable speed of light (VSL) model would be more appropriate. Such a model is the Polarizable Vacuum Model of General Relativity, where the coordinate speed of light is used in the coordinates of a distant observer, c/K. I keep trying to bring this into the conversation and you keep kicking us back to SR and LT's. So let me try one last time.
VSL to me typically would mean a local observer measures a different speed of light. Can we agree to reserve that term for that to avoid confusion (and then proceed to not use it, because neither of us are discussing that. (At least I don't think you mean to.)
Since I don't think intergalactic travel will be possible anytime soon, let's stick to interstellar, within our own galaxy. The Milky Way has a supermassive black hole at it's center, and a lot of mass near the center that increases the gravitational potential at our solar system, relative to the center of gravity, (CoG) of the galaxy.
I stuck to interstellar in my example as well, but if you are proposing FTL, intergalactic starts to sound more feasible, and should be consistent as well.
To summarize, all matter in the galaxy is immersed in a background gravitational field that sets the "base line" for length contraction and time dilation as variables, between r = ∞ and the event horizon of the BH, r = Rs.
You seem to have forgotten your own comments from earlier, but from a local frame the absolute value of K is irrelevant and immeasurable. You also seem to have lost track of what you need to be arguing. I gave you a numbered list before. The first thing you need to do is show that there are different curvatures/K values across the interstellar distances. Without this, it doesn't matter that there is a black hole 50000 light years away, the local gradient of K is negligible across a distance of 10 light years, and not even necessarily in a direction governed by that black hole. (If you disagree, give a numeric example please.)
Now, we turn on "time" so that the model is no longer time-independent and let things move. Any motion is relative to the CoG of the galaxy. Any object that accelerates to a high velocity such as 0.6c, has increased its total Energy, and therefore its potential energy relative to the CoG.
This is an assertion that the center of the galaxy frame is special in a way that is simply contradictory to both SR and GR. This is not just an "interpretation of GR" but a completely new theory and it is unclear if it makes a single prediction consistent with experimental data.
In this formulation, there is never an opportunity to go backwards in time.
You have not shown this in any way, shape, or form.
There is no paradox and it is more "realistic" than the STR. Now, we could take a Machian/Woodward view, where in flat space-time an object still has a gravitational potential relative to the distant stars. In which case, the same argument applies. Any change in the relative energy of an object changes it's gravitational potential energy relative to the distant stars. However, STR is the special case where there is no gravitational field. Hence, it is not applicable in this model.
GR reduces to SR in flat space time. When you set up a scenario like this where spacetime is effectively flat, it doesn't matter if there is gravity, the results of SR hold. If you say SR doesn't hold in flat spacetime, you are saying GR doesn't either. You are then talking about a new, distinct theory. Good luck formalizing it and showing that it explains experimental observations at least as well as GR. "Relative to the distant stars" really is a poorly defined concept anyway.
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A variable speed of light (VSL) model would be more appropriate. Such a model is the Polarizable Vacuum Model of General Relativity, where the coordinate speed of light is used in the coordinates of a distant observer, c/K. I keep trying to bring this into the conversation and you keep kicking us back to SR and LT's. So let me try one last time.
VSL to me typically would mean a local observer measures a different speed of light. Can we agree to reserve that term for that to avoid confusion (and then proceed to not use it, because neither of us are discussing that. (At least I don't think you mean to.)
There are no theories where a local observer measures something other than "c" locally. VSL is generally accepted as the type of theory I am describing. See R. Dicke 1957...
https://en.wikipedia.org/wiki/Variable_speed_of_light (https://en.wikipedia.org/wiki/Variable_speed_of_light)
Since I don't think intergalactic travel will be possible anytime soon, let's stick to interstellar, within our own galaxy. The Milky Way has a supermassive black hole at it's center, and a lot of mass near the center that increases the gravitational potential at our solar system, relative to the center of gravity, (CoG) of the galaxy.
I stuck to interstellar in my example as well, but if you are proposing FTL, intergalactic starts to sound more feasible, and should be consistent as well.
It would be consistent, but realistically, unless we can achieve speeds 1000's of times > c, it's not gonna happen.
To summarize, all matter in the galaxy is immersed in a background gravitational field that sets the "base line" for length contraction and time dilation as variables, between r = ∞ and the event horizon of the BH, r = Rs.
You seem to have forgotten your own comments from earlier, but from a local frame the absolute value of K is irrelevant and immeasurable. You also seem to have lost track of what you need to be arguing. I gave you a numbered list before. The first thing you need to do is show that there are different curvatures/K values across the interstellar distances. Without this, it doesn't matter that there is a black hole 50000 light years away, the local gradient of K is negligible across a distance of 10 light years, and not even necessarily in a direction governed by that black hole. (If you disagree, give a numeric example please.)
Now, we turn on "time" so that the model is no longer time-independent and let things move. Any motion is relative to the CoG of the galaxy. Any object that accelerates to a high velocity such as 0.6c, has increased its total Energy, and therefore its potential energy relative to the CoG.
This is an assertion that the center of the galaxy frame is special in a way that is simply contradictory to both SR and GR. This is not just an "interpretation of GR" but a completely new theory and it is unclear if it makes a single prediction consistent with experimental data.
No. This is an assertion that time dilation and length contraction depend solely on the relative gravitational potential. Velocity just changes the energy content of the ship "relative" to the CoG base-line it started with.
In this formulation, there is never an opportunity to go backwards in time.
You have not shown this in any way, shape, or form.
There is no paradox and it is more "realistic" than the STR. Now, we could take a Machian/Woodward view, where in flat space-time an object still has a gravitational potential relative to the distant stars. In which case, the same argument applies. Any change in the relative energy of an object changes it's gravitational potential energy relative to the distant stars. However, STR is the special case where there is no gravitational field. Hence, it is not applicable in this model.
GR reduces to SR in flat space time. When you set up a scenario like this where spacetime is effectively flat, it doesn't matter if there is gravity, the results of SR hold. If you say SR doesn't hold in flat spacetime, you are saying GR doesn't either. You are then talking about a new, distinct theory. Good luck formalizing it and showing that it explains experimental observations at least as well as GR. "Relative to the distant stars" really is a poorly defined concept anyway.
You need to do your homework. I used the Schwarzschild solution of GR as the background metric in my previous post. There was nothing new there except my interpretation. I changed nothing. I have already given you numerous references that refute your assumptions and the conclusions you keep jumping to, that this is somehow inconsistent with GR. I can't plug this knowledge into your head, you need to actually try to learn something new. This model has been around since 1957 and its "numerical" equivalence to GR was shown by Puthoff in 1999, and updated by J. Depp in 2005. The references are posted on page 7 of this thread.
Start here: https://arxiv.org/pdf/gr-qc/9909037.pdf
I'm saying that time dilation and length contraction are due to the relative potential in the gravitational field. The energy content of the moving body simply changes that potential, but no matter what the gravitational potential is, or what the rate of time on a clock is; it's just a relative potential. Time still moves forward.
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No. This is an assertion that time dilation and length contraction depend solely on the relative gravitational potential. Velocity just changes the energy content of the ship "relative" to the CoG base-line it started with.
What exactly do you mean by gravitational potential in the context of GR?
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A variable speed of light (VSL) model would be more appropriate. Such a model is the Polarizable Vacuum Model of General Relativity, where the coordinate speed of light is used in the coordinates of a distant observer, c/K. I keep trying to bring this into the conversation and you keep kicking us back to SR and LT's. So let me try one last time.
VSL to me typically would mean a local observer measures a different speed of light. Can we agree to reserve that term for that to avoid confusion (and then proceed to not use it, because neither of us are discussing that. (At least I don't think you mean to.)
There are no theories where a local observer measures something other than "c" locally. VSL is generally accepted as the type of theory I am describing. See R. Dicke 1957...
https://en.wikipedia.org/wiki/Variable_speed_of_light (https://en.wikipedia.org/wiki/Variable_speed_of_light)
You are the one who needs to go read that page.
From the specific section you referenced:
Dicke considered a cosmology where c decreased in time, providing an alternative explanation to the cosmological redshift
This is really not at all what you had been saying. (And there is a difference between a local measurement of the speed of light, and the speed of light somewhere else in the universe under this type of theory.)
It would be consistent, but realistically, unless we can achieve speeds 1000's of times > c, it's not gonna happen.
All of your arguments so far for why FTL "can't" happen (to the extent they have any validity) have depended on sufficiently not flat spacetime. You have yet to propose any meaningful limits on your FTL drive, so what is the problem with 1000*c?
No. This is an assertion that time dilation and length contraction depend solely on the relative gravitational potential. Velocity just changes the energy content of the ship "relative" to the CoG base-line it started with.
That last phrase there sounds like you are talking about things having a memory again.
You need to do your homework. I used the Schwarzschild solution of GR as the background metric in my previous post. There was nothing new there except my interpretation. I changed nothing. I have already given you numerous references that refute your assumptions and the conclusions you keep jumping to, that this is somehow inconsistent with GR.
I need to learn something new? After you gave inconsistent explanations of the "twin paradox"? And now pointed me to a wiki page that you apparently need to read yourself.
Equivalence to GR means the exact same predictions as GR. "Interpretation" really can't change these.
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Interesting data here;https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.080503 (https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.080503)
Einstein hated "spooky interaction at a distance", because, effectively, it allowed for instantaneous data transmission between two particles, regardless of the distance. The act of measuring one entangled particle's characteristics, immediately affected the characteristics of the other.
In other words; one could change the characteristics of two entangled particles, over a distance of light years, INSTANTANEOUSLY by measuring the characteristics of one of the two particles.
No time travel involved. No paradoxes. Simply quantum physics.
I'm not saying that this would allow any sort of FTL flight, but it dose lend credence to the possibility that it might be possible, so long as one's arrival does not occur prior to one's departure from one's point of origin.
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Interesting data here;https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.080503 (https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.080503)
Einstein hated "spooky interaction at a distance", because, effectively, it allowed for instantaneous data transmission between two particles, regardless of the distance. The act of measuring one entangled particle's characteristics, immediately affected the characteristics of the other.
In other words; one could change the characteristics of two entangled particles, over a distance of light years, INSTANTANEOUSLY by measuring the characteristics of one of the two particles.
No time travel involved. No paradoxes. Simply quantum physics.
"simple" and "quantum physics" are antonyms. The no communication theorem strictly prevents the "change" from one that there would be any way to tell that the change had happened.
I'm not saying that this would allow any sort of FTL flight, but it dose lend credence to the possibility that it might be possible, so long as one's arrival does not occur prior to one's departure from one's point of origin.
No, it doesn't really lend credence to the possibility. "so long as one's arrival does not occur prior to one's departure from one's point of origin." is not a well defined sentence. The only way to ensure that one's arrival does not occur prior to one's departure is to not travel FTL. Otherwise due to relativity, your arrival is guaranteed to be prior to your departure in some frame. As discussed at length in this thread, all inertial frames are equivalent, so you can't say one frame is the one to determine order of events in without throwing out relativity.
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I think an imaginative but scientifically sound way to look at the possibility of FTL can start with realizing that empty space (the vacuum) can be usefully thought of a superconducting/superfluid material. This isn't controversial but mainstream physics (ref. Wilczek, Volovik...).
Slightly more imaginative is the idea that our physics is really the physics of quasiparticles in a "trans-Planckian" medium (ref. Volovik's The Universe in a Helium Droplet). So the particles and fields that we see are something like phonons, excitation of a more fundamental underlying substrate that we don't see.
Einstein's metric itself could an be emergent property of the substrate. In condensed materials, quasiparticles move with a maximum speed determined by an effective spacetime metric. This maximum speed is much less than the speed of light in vacuum.
Similarly, the maximum speed in the underlying "real world" from which our particles and fields emerge as quasiparticle-like excitations could be much higher than our speed of light in vacuum.
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This thread is not specifically about the possibility of FTL and certainly not about any particular theory.
Any valid theory would at least deserve it's own thread.
This thread is about how the very famous paradoxes could be avoided. For example, it probably has to explain how simultaneous could even be defined between distant points in space.
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I think an imaginative but scientifically sound way to look at the possibility of FTL can start with realizing that empty space (the vacuum) can be usefully thought of a superconducting/superfluid material. This isn't controversial but mainstream physics (ref. Wilczek, Volovik...).
Slightly more imaginative is the idea that our physics is really the physics of quasiparticles in a "trans-Planckian" medium (ref. Volovik's The Universe in a Helium Droplet). So the particles and fields that we see are something like phonons, excitation of a more fundamental underlying substrate that we don't see.
Einstein's metric itself could an be emergent property of the substrate. In condensed materials, quasiparticles move with a maximum speed determined by an effective spacetime metric. This maximum speed is much less than the speed of light in vacuum.
Similarly, the maximum speed in the underlying "real world" from which our particles and fields emerge as quasiparticle-like excitations could be much higher than our speed of light in vacuum.
That is basically what people thought in the 19th Century -- that there was a substrate and light was moving in that substrate. If that's the case, it should be possible to detect which frame of reference the substrate is in -- i.e. it's movement relative to the Earth. The Michelson-Morley experiment, among others, tried to detect such movement relative to a substrate. The failure of such experiments to get results consistent with a substrate led to the development of relativity, which explains experimental data much better than any substrate theory.
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I think an imaginative but scientifically sound way to look at the possibility of FTL can start with realizing that empty space (the vacuum) can be usefully thought of a superconducting/superfluid material. This isn't controversial but mainstream physics (ref. Wilczek, Volovik...).
Slightly more imaginative is the idea that our physics is really the physics of quasiparticles in a "trans-Planckian" medium (ref. Volovik's The Universe in a Helium Droplet). So the particles and fields that we see are something like phonons, excitation of a more fundamental underlying substrate that we don't see.
Einstein's metric itself could an be emergent property of the substrate. In condensed materials, quasiparticles move with a maximum speed determined by an effective spacetime metric. This maximum speed is much less than the speed of light in vacuum.
Similarly, the maximum speed in the underlying "real world" from which our particles and fields emerge as quasiparticle-like excitations could be much higher than our speed of light in vacuum.
That is basically what people thought in the 19th Century -- that there was a substrate and light was moving in that substrate. If that's the case, it should be possible to detect which frame of reference the substrate is in -- i.e. it's movement relative to the Earth. The Michelson-Morley experiment, among others, tried to detect such movement relative to a substrate. The failure of such experiments to get results consistent with a substrate led to the development of relativity, which explains experimental data much better than any substrate theory.
Not so fast. Today's quantum field theory is just that, there is a "field" which can only be observed by the "particle excitations" of the field. The field is not the sum of the particles, the particles are the excitations of the field and may be created or annihilated at any time. The field is the "substrate" as you put it, but is unobservable if not for its particle excitations.
Take the EM Zero Point Field for example. Motion relative to the ZPF, (i.e., any EM spectral energy density proportional to frequency3) is unobservable. Yet we can observe it in the Casimir effect and the Lamb shift. More importantly, uniform-changes in the spectral energy density of the EM ZPF are equally unobservable.
Point being, regarding the statement; "If that's the case, it should be possible to detect which frame of reference the substrate is in --" is an assumption that has been proven false by the existence of a ZPF and QFT in general.
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I think an imaginative but scientifically sound way to look at the possibility of FTL can start with realizing that empty space (the vacuum) can be usefully thought of a superconducting/superfluid material. This isn't controversial but mainstream physics (ref. Wilczek, Volovik...).
Slightly more imaginative is the idea that our physics is really the physics of quasiparticles in a "trans-Planckian" medium (ref. Volovik's The Universe in a Helium Droplet). So the particles and fields that we see are something like phonons, excitation of a more fundamental underlying substrate that we don't see.
Einstein's metric itself could an be emergent property of the substrate. In condensed materials, quasiparticles move with a maximum speed determined by an effective spacetime metric. This maximum speed is much less than the speed of light in vacuum.
Similarly, the maximum speed in the underlying "real world" from which our particles and fields emerge as quasiparticle-like excitations could be much higher than our speed of light in vacuum.
That is basically what people thought in the 19th Century -- that there was a substrate and light was moving in that substrate. If that's the case, it should be possible to detect which frame of reference the substrate is in -- i.e. it's movement relative to the Earth. The Michelson-Morley experiment, among others, tried to detect such movement relative to a substrate. The failure of such experiments to get results consistent with a substrate led to the development of relativity, which explains experimental data much better than any substrate theory.
Not so fast. Today's quantum field theory is just that, there is a "field" which can only be observed by the "particle excitations" of the field. The field is not the sum of the particles, the particles are the excitations of the field and may be created or annihilated at any time. The field is the "substrate" as you put it, but is unobservable if not for its particle excitations.
Take the EM Zero Point Field for example. Motion relative to the ZPF, (i.e., any EM spectral energy density proportional to frequency3) is unobservable. Yet we can observe it in the Casimir effect and the Lamb shift. More importantly, uniform-changes in the spectral energy density of the EM ZPF are equally unobservable.
Point being, regarding the statement; "If that's the case, it should be possible to detect which frame of reference the substrate is in --" is an assumption that has been proven false by the existence of a ZPF and QFT in general.
A field is not a "substrate" in the sense that the original poster was talking about -- something that could give a slower speed of light in the substrate than the speed of light in a true vacuum.
If it can give light a different speed, it has a frame of reference associated with it, unless you want to toss all of known physics and come up with a completely new theory.
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The topic on this thread is just how paradoxes are resolved though.
So for example, in this case all I want to know is if the paradoxes are being resolved by limiting FTL to be with respect to a special frame. If so then what is that frame. If not, then how do you resolve the paradoxes, how do you define "instantaneous" between two events?
The explanation has to make sense without being a physicist. You can't sell FTL to a tourist with the slogan "buy this trip to alpha centauri. The outcome is indescribable".
IMO we have one ok resolution using a special frame. (instantaneous FTL travel is between points of the same CMB temperature). I don't think this actually breaks relativity. It does not require any current test to stop working that i am aware of. I totally accept that it is like sewing a 5th leg on your racehorse and no reason has been presented of why you should do so. Im only concerned with paradoxes and if you can actually describe what you mean when you say FTL. Otherwise you might as well replace "FTL" with "Smurf", and produce detailed mathematics to prove you can smurf your smurf.
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You say above that this thread is not about the possibility of FTL, and that the topic is how paradoxes are resolved and it has to make sense without being a physicist. Sounds like you can have any two out of three.
The easiest way to resolve a paradox is to avoid it in the first place i.e., admit that FTL is impossible. Resolved and no physics degree needed.
Adding epicycles and aether and throwing away Occam's razor requires the intended audience to be able to understand why those things are necessary even though they make no sense. That requires math and a good knowledge of real physics, i.e., a physicist.
You've set yourself an impossible task that will accomplish nothing. Just posit that the same space-fairy magic that makes FTL possible takes care of the paradoxes and move on with your life. Surely you have something better to do.
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That is basically what people thought in the 19th Century -- that there was a substrate and light was moving in that substrate. If that's the case, it should be possible to detect which frame of reference the substrate is in -- i.e. it's movement relative to the Earth. The Michelson-Morley experiment, among others, tried to detect such movement relative to a substrate. The failure of such experiments to get results consistent with a substrate led to the development of relativity, which explains experimental data much better than any substrate theory.
Not so fast. Today's quantum field theory is just that, there is a "field" which can only be observed by the "particle excitations" of the field. The field is not the sum of the particles, the particles are the excitations of the field and may be created or annihilated at any time. The field is the "substrate" as you put it, but is unobservable if not for its particle excitations.
Take the EM Zero Point Field for example. Motion relative to the ZPF, (i.e., any EM spectral energy density proportional to frequency3) is unobservable. Yet we can observe it in the Casimir effect and the Lamb shift. More importantly, uniform-changes in the spectral energy density of the EM ZPF are equally unobservable.
Point being, regarding the statement; "If that's the case, it should be possible to detect which frame of reference the substrate is in --" is an assumption that has been proven false by the existence of a ZPF and QFT in general.
A field is not a "substrate" in the sense that the original poster was talking about -- something that could give a slower speed of light in the substrate than the speed of light in a true vacuum.
If it can give light a different speed, it has a frame of reference associated with it, unless you want to toss all of known physics and come up with a completely new theory.
Your statement is not well defined. In a Schwarzschild metric background for instance, in any "local" approximation of an inertial reference frame, c = c, is a constant. But take any one of those inertial frames, such as the one of a very distant observer, and from his perspective, the coordinate speed of light is a function of radial distance from the CoM.
c(r) = c*(1 - 2GM/rc^2)
In GR, the coordinate speed of light is not a constant, but in any local approximation of an inertial frame, it is. So your statement; "If it can give light a different speed, it has a frame of reference associated with it, unless you want to toss all of known physics and come up with a completely new theory.", is once again an assumption that is refuted by GR and also by the Polarizable Vacuum Model of GR, which show we can have it both ways, and it doesn't require us to toss out anything.
You assume c is constant in the local inertial frame, GR shows the coordinate speed c(r) is not constant, when viewed from a distant inertial frame. In one frame, it is obvious that c(r) is a variable with distance, but like a fish that doesn't know he's in the water, in the local frame, that change in c can't be measured or observed.
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You assume c is constant in the local inertial frame, GR shows the coordinate speed c(r) is not constant, when viewed from a distant inertial frame. In one frame, it is obvious that c(r) is a variable with distance, but like a fish that doesn't know he's in the water, in the local frame, that change in c can't be measured or observed.
The relevant speed he is discussing clearly seems to be the proper speed, not the coordinate speed.
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You say above that this thread is not about the possibility of FTL, and that the topic is how paradoxes are resolved and it has to make sense without being a physicist. Sounds like you can have any two out of three.
No I don't think so. Let me explain again.
The reason I have been very clear that the answer must make sense without being a physicist is because several replies were of the form: "There is no paradox because <insert jargon>". This is of no use because you have to be able explain what someone actually experiences if they attempt to implement one of the standard paradoxes. Obviously, someone who takes an FTL trip has to experience a set of events even if they are not a physicist.
Currently we have one candidate for resolving paradoxes I consider "good enough for science fiction". I repeat, It is not about being true, just about being describable.
One way you could contribute is coming up with other candidates of resolutions to paradoxes, that do not require tests we have already done to start returning different results.
Another way you could contribute is by producing clear examples of how physics would break even assuming this candidate, and begin producing nonsensical, paradoxical claims.
My hope, as an outcome for this entire thread, is that if any other thread starts to discuss some particular FTL proposal, we will be able to get the proponent to at least clarify what they mean by FTL, by placing it in one of these categories.
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You assume c is constant in the local inertial frame, GR shows the coordinate speed c(r) is not constant, when viewed from a distant inertial frame. In one frame, it is obvious that c(r) is a variable with distance, but like a fish that doesn't know he's in the water, in the local frame, that change in c can't be measured or observed.
The relevant speed he is discussing clearly seems to be the proper speed, not the coordinate speed.
The original poster specifically said;
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Einstein's metric itself could an be emergent property of the substrate. In condensed materials, quasiparticles move with a maximum speed determined by an effective spacetime metric. This maximum speed is much less than the speed of light in vacuum.
That is what I just said about c(r), the coordinate speed of light is determined by the "spacetime metric". He wasn't referring to the "proper speed".
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Einstein's metric itself could an be emergent property of the substrate. In condensed materials, quasiparticles move with a maximum speed determined by an effective spacetime metric. This maximum speed is much less than the speed of light in vacuum.
That is what I just said about c(r), the coordinate speed of light is determined by the "spacetime metric". He wasn't referring to the "proper speed".
He was talking about speed of light relative to a (local) substrate. The relevant speed is the proper speed not the coordinate speed. You know what proper speed means right? The way you put it in quotes while not putting coordinate speed in quotes makes me think that you think I just made up the term.
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Here's something, that has been exercising my mind a little of late; from an outsider with, probably, enough physics to be dangerous.
GR seems to tell me that any event in the future in my inertial frame, lies in the past for an infinite number of other frames.
Where does that leave free will?
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Here's something, that has been exercising my mind a little of late; from an outsider with, probably, enough physics to be dangerous.
GR seems to tell me that any event in the future in my inertial frame, lies in the past for an infinite number of other frames.
Where does that leave free will?
There is a defined future and past for you, your "future light cone" and "past light cone" The future consists of all events you can effect and the past of all events that can effect you. There are also events that are neither "spacelike separated events" are ones that are indeterminate whether they are in your future or past, so they cannot affect or be affected by your current state. None of this directly prevents free will.
As for free will, most of physics is deterministic, which means no free will. With quantum mechanics, some interpretations are not deterministic, which means quantum explicitly has a loophole for freewill. (There are both deterministic and non-deterministic interpretations, but someone found a way to test a certain class of deterministic interpretations and they have been found to not hold. As a result, many physicists have been resigned to accept the non-deterministic interpretation, since the remaining deterministic ones are unattractive. This doesn't matter though since as far as we know there is no way to tell them apart.)
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Here's something, that has been exercising my mind a little of late; from an outsider with, probably, enough physics to be dangerous.
GR seems to tell me that any event in the future in my inertial frame, lies in the past for an infinite number of other frames.
Where does that leave free will?
There is a defined future and past for you, your "future light cone" and "past light cone" The future consists of all events you can effect and the past of all events that can effect you. There are also events that are neither "spacelike separated events" are ones that are indeterminate whether they are in your future or past, so they cannot affect or be affected by your current state. None of this directly prevents free will.
As for free will, most of physics is deterministic, which means no free will. With quantum mechanics, some interpretations are not deterministic, which means quantum explicitly has a loophole for freewill. (There are both deterministic and non-deterministic interpretations, but someone found a way to test a certain class of deterministic interpretations and they have been found to not hold. As a result, many physicists have been resigned to accept the non-deterministic interpretation, since the remaining deterministic ones are unattractive. This doesn't matter though since as far as we know there is no way to tell them apart.)
Thank you for your thoughtful reply; it doesn't quite address the question I attempted to pose. I shall return when I have reformulated it.
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Kelvinzero, here is a response for a hard science fictional viewpoint. There is no way to have FTL drive without causing paradoxes in SR and GR. However, the complete answer is not so simple.
First there are two question tied together in the simple term FTL. One must first separate them, as they are not identical. They are 1.) traveling faster that light itself. And 2.) traveling faster that c. Those question are not the same.
Question #1. - Traveling faster than light itself. We have no data or testable theory to work with. The only thing we would have is that whatever new theory and/or data would have to reduce to GR and SR at sub-light speeds; the same concept that SR and GR reduce to Newtonian mechanics at very slow speeds.
Question #2. - Traveling faster than c. Here we have theory and testable methodologies to work with. To forestall the back-and-forth, I will describe them here. C, (the speed of light in a vacuum), has been tested an enormous number of times, with a consistent result. This is granted. The question is not what is c , but why is c? For theory on that, one has to go back before GR and SR, to Maxwell's Equations. More particularly, to the boundary requirements of Maxwell's Equations. The second boundary condition defines c as 1 /square root of (the permittivity of a vacuum * the permeability of a vacuum).
This was a major bone of contention for SR when it was published. The issue was finally settled by 1915, with the viewpoint that there was no way to change those aspects of a vacuum, therefore it was a moot point. The result was that c became canonical to physics.
However, in the late 1990's, ways were discovered to alter Permittivity and Permeability, initially to create materials that had both negative Permittivity and Permeability, which should cause a number of bizarre effects. Most (but not all) of these have been tested, and in every tested case proved to be actual. For brevity, I will leave most of them out, but mention only 2. The first, was that due to certain quantum related aspects to light, which are imaginary under positive Permittivity and Permeability conditions, became real under negative conditions, which allows items less than the length of the a wavelength of light, to be visualized by that wavelength. The second, and much more relevant, was the first boundary condition of Maxwell's Equations, which says that the wave propagation in a positive material propagates in the same direction as the photon is travelling in. In a negative material, it should propagate in the opposite direction. Experiments have shown that this is the case with negative Permittivity and Permeability materials.
Which leads to the question #2 above. If you made a field with lower Permittivity and Permeability than a vacuum, what is the speed of light under that field? C, or the value that Maxwell's second boundary condition would calculate? If it is the latter, there is the theory for a faster than c drive. Same equations as GR and SR, only with c as a variable. (Of course, no theory on the interrelation between different frames with different valid values of c. The paradoxes would have to be solved by that new theory.) When you set c to the standard permittivity and pearmeability value of the universe, it reduces to GR and SR.
To reduce this for a “hard SF” FTL drive, I leave to the SF writer. . .
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Kelvinzero, here is a response for a hard science fictional viewpoint. There is no way to have FTL drive without causing paradoxes in SR and GR. However, the complete answer is not so simple.
First there are two question tied together in the simple term FTL. One must first separate them, as they are not identical. They are 1.) traveling faster that light itself. And 2.) traveling faster that c. Those question are not the same.
Question #1. - Traveling faster than light itself. We have no data or testable theory to work with. The only thing we would have is that whatever new theory and/or data would have to reduce to GR and SR at sub-light speeds; the same concept that SR and GR reduce to Newtonian mechanics at very slow speeds.
Question #2. - Traveling faster than c. Here we have theory and testable methodologies to work with. To forestall the back-and-forth, I will describe them here. C, (the speed of light in a vacuum), has been tested an enormous number of times, with a consistent result. This is granted. The question is not what is c , but why is c? For theory on that, one has to go back before GR and SR, to Maxwell's Equations. More particularly, to the boundary requirements of Maxwell's Equations. The second boundary condition defines c as 1 /square root of (the permittivity of a vacuum * the permeability of a vacuum).
This was a major bone of contention for SR when it was published. The issue was finally settled by 1915, with the viewpoint that there was no way to change those aspects of a vacuum, therefore it was a moot point. The result was that c became canonical to physics.
However, in the late 1990's, ways were discovered to alter Permittivity and Permeability, initially to create materials that had both negative Permittivity and Permeability, which should cause a number of bizarre effects. Most (but not all) of these have been tested, and in every tested case proved to be actual. For brevity, I will leave most of them out, but mention only 2. The first, was that due to certain quantum related aspects to light, which are imaginary under positive Permittivity and Permeability conditions, became real under negative conditions, which allows items less than the length of the a wavelength of light, to be visualized by that wavelength. The second, and much more relevant, was the first boundary condition of Maxwell's Equations, which says that the wave propagation in a positive material propagates in the same direction as the photon is travelling in. In a negative material, it should propagate in the opposite direction. Experiments have shown that this is the case with negative Permittivity and Permeability materials.
Which leads to the question #2 above. If you made a field with lower Permittivity and Permeability than a vacuum, what is the speed of light under that field? C, or the value that Maxwell's second boundary condition would calculate? If it is the latter, there is the theory for a faster than c drive. Same equations as GR and SR, only with c as a variable. (Of course, no theory on the interrelation between different frames with different valid values of c. The paradoxes would have to be solved by that new theory.) When you set c to the standard permittivity and pearmeability value of the universe, it reduces to GR and SR.
To reduce this for a “hard SF” FTL drive, I leave to the SF writer. . .
You just described the Polarizable Vacuum Model of General Relativity, which was first considered by Dicke, and later by Putoff and myself.
http://forum.nasaspaceflight.com/index.php?topic=40959.msg1583932#msg1583932 (http://forum.nasaspaceflight.com/index.php?topic=40959.msg1583932#msg1583932)
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Kelvinzero, here is a response for a hard science fictional viewpoint. There is no way to have FTL drive without causing paradoxes in SR and GR. However, the complete answer is not so simple.
Hi RSE, we seem to have found a simple way to describe FTL without paradoxes. I summarised what we have so far in the OP. (It is possible this gimmick only works for special relativity. It assumes things are pretty flat.)
There is absolutely no evidence or suggestion given that such a loophole exists. I repeat, It is not about being true, just about being describable.
(I actually started this thread thinking we could not even find this, and that a paradox could be formed with a single FTL flight making frame of reference irrelevant. I thought we would have to introduce massive spacewalls or such that pretty much isolate regions of space visited by FTL. Turns out it is not that bad)
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Guys, I registered just to say this - this entire thread encapsulates one giant misunderstanding between the two parties.
It seems there are two things confused:
1. "FTL" - Faster Than Light travel in space, which YES, would cause paradoxes and allow messages being sent back in time (like shown on the diagrams and the PBS video).
2. Warp-drive, "Jump Drive", etc. are actually considered an Apparent FTL,
wikipedia quote (https://en.wikipedia.org/wiki/Faster-than-light):
Apparent FTL is not excluded by general relativity, however, any Apparent FTL physical plausibility is speculative. Examples of Apparent FTL proposals are the Alcubierre drive and the traversable wormhole.
So yes, if you travel using FTL drive, in space, you will open door to a full range of paradoxes, incl. Temporal Viber messaging app if you like.
If you jump around different coordinates in space, via worm-hole or a warp-drive, these paradoxes do no apply. There is no acceleration work being done. You take a patch of space (your ship and then some space around it) from place X and basically "teleport" it to a place Y. Clock speed/rates are NOT affected. Time on board such ships goes at same rate as at the place it started from.
Now, having said that, there is something that is usually not considered when it comes to A-FTL (Apparent FTL):
If we take a patch of space with a reference frame of position X (Earth#1), warp through space to position Y (with Earth#2 for example), lets say 150k light years across our galaxy, then YES, we have moved 150k light years. However, the moment we turn off the drive we wouldn't see the Earth#2 (our original target) waiting for us in front of the ship for very long - it would instead instantly move away from us (since its in different reference frame / moving at different speed/direction etc.). So technically, A-FTL ships on top of "jumping around" would also have to use regular, relativistic drives to match the target reference frames.
Hopefully this cleared some things up. Thank you.
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If you jump around different coordinates in space, via worm-hole or a warp-drive, these paradoxes do no apply. There is no acceleration work being done. You take a patch of space (your ship and then some space around it) from place X and basically "teleport" it to a place Y. Clock speed/rates are NOT affected. Time on board such ships goes at same rate as at the place it started from.
As I have told this to WarpTech repeatedly, the time experienced by the people on board the ship is unrelated to the paradoxes. Unless the existence of the wormhole you used prevents the creation of a wormhole by another ship, it is trivial to implement the paradox.
So technically, A-FTL ships on top of "jumping around" would also have to use regular, relativistic drives to match the target reference frames.
This is not a significant problem, which is why people don't bother discussing it, and irrelevant to paradoxes.
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Guys, I registered just to say this - this entire thread encapsulates one giant misunderstanding between the two parties.
no misundestanding
It seems there are two things confused:
1. "FTL" - Faster Than Light travel in space, which YES, would cause paradoxes and allow messages being sent back in time (like shown on the diagrams and the PBS video).
2. Warp-drive, "Jump Drive", etc. are actually considered an Apparent FTL,
wikipedia quote (https://en.wikipedia.org/wiki/Faster-than-light):
Apparent FTL is not excluded by general relativity, however, any Apparent FTL physical plausibility is speculative. Examples of Apparent FTL proposals are the Alcubierre drive and the traversable wormhole.
the two things are not being confused, and we know them pretty well.
If you jump around different coordinates in space, via worm-hole or a warp-drive, these paradoxes do no apply. There is no acceleration work being done. You take a patch of space (your ship and then some space around it) from place X and basically "teleport" it to a place Y. Clock speed/rates are NOT affected. Time on board such ships goes at same rate as at the place it started from.
you are showing here that it's you who do not understand how things work.
your problem lies in thinking you are travelling through 3D space and time is another thing, separate.
Time and space are deeply connected. There is no universal time. So it doesn´t matter you take a bubble of space time with you, if you travelled faster than the speed of causality, you will still may be dropped in a moment of time BEFORE you departed the moment you turn it off.
Hopefully this cleared some things up. Thank you.
yes, it's clear you are not very aware of how light cones and causality works. I posted some videos pages ago. Watch them again and again.
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Time and space are deeply connected. There is no universal time. So it doesn´t matter you take a bubble of space time with you, if you travelled faster than the speed of causality, you will still may be dropped in a moment of time BEFORE you departed the moment you turn it off.
I get this part, but I still ask "so what?"
A ship's sudden appearance in a moment in the past won't affect the moment it left the present until the speed of causality reaches it. So therefore, can't a paradox never be created because the effects of causality can't reach the origination point prior to the moment of departure? It seems to me that I can't affect the local time in the past and create a paradox unless I use a time machine that ignores distance. An FTL ship can't do it.
E.G., if in 2017 I warp out 100 light years in only 2 years of local time, I've gone back in time 100 years. But it still takes 100 years for me to transmit my radio message of "Oh crap, I just looked through a my ship's big telescope back at the Earth, and Shoeless Joe is cheating at baseball! Don't place your bets on Chicago" to get back to Earth 100 years later (in 2019). If I instead hop in my ship and warp back to Earth, now 4 years have passed locally, and no one on Earth cares about the Black Sox in 2021, but I've got some cool videos of what Earth looked like in the past that I recorded through my ship's telescope.
Hopefully this cleared some things up. Thank you.
yes, it's clear you are not very aware of how light cones and causality works. I posted some videos pages ago. Watch them again and again.
Please play nice. Polite questions and answers are the soul of NSF. If we wanted romper room, we'd take it to Reddit.
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E.G., if in 2017 I warp out 100 light years in only 2 years of local time, I've gone back in time 100 years. But it still takes 100 years for me to transmit my radio message of "Oh crap, I just looked through a my ship's big telescope back at the Earth, and Shoeless Joe is cheating at baseball! Don't place your bets on Chicago" to get back to Earth 100 years later (in 2019).
I don't think you have thought through your own description here. You are describing going into the past and then seeing light from the future.
Anyway, the real problem has been described multiple times in these threads. The short version is that you need to recognize that since there are frames where you travelled backwards in time, then travelling FTL the same way back the other direction means going even further back in time.
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So yes, if you travel using FTL drive, in space, you will open door to a full range of paradoxes, incl. Temporal Viber messaging app if you like.
If you jump around different coordinates in space, via worm-hole or a warp-drive, these paradoxes do no apply.
By cunning use of FTL, I responded to this before you posted:
The problem is that you can produce paradoxes just by sending messages. You can ignore what the postman experiences.
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It seems to me that I can't affect the local time in the past and create a paradox unless I use a time machine that ignores distance.
Hi sghill, this has been reiterated many times, here is another way of underlining the problem.
How do you define 'simultaneous' between two distant points?
Consider just that. What answer would you come up with?
Here is a very reasonable sounding approach:
* Place a beacon exactly halfway between these to points, A & B.
* The beacon emits a flash of light.
* You claim that the flash arrives at A at the exact same time as it arrives at B.
* Therefore, an instantaneous (ftl) message from A sent when it detects the beacon would be received by b when it detects that beacon.
If you buy that argument you trivially have a paradox, because someone in a different inertial frame will see the light pulse arriving at A and B at different times. They could use one instantaneous communication in their frame of reference to send a message to A, and another also in their frame of reference to get the information back from B before they sent it.
Suffice it to say that it turns out that our really reasonable way of defining simultaneous with a beacon between two points was nonsense.
So how would you define simultaneous?
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Sorry, but the statements I see on this thread, like with the EM drive thread, crack me up. People post such strongly worded statements on the definite and immutable nature of the physical world around us. Because, you know, we know. Right?
Because, you know, we knew the world was a disk and the heavens above revolved about us.
Until it was proven wrong.
Then of course all was right in the world when Newtonian physics set it all straight. We finally had, literally, conservative physics. And any direction of thought that strayed from these new tenants was blasphemy and the spewers of such treason were dealt with accordingly. But hey, what now do we hear? A particle is a wave? A wave a particle? Where's a cat in a box when a tree falls... quantum leaps of faith?
So now - apparently now - we've got physics all trussed up, flipped over and hog tied. It's now our complete plaything because we've tamed it.
When will we learn - we know nothing in the big picture - hell, we can't even see what the big picture is. So stay in your reference frame and argue the world as you want it perceived, but just take a moment to reflect back into the past and see that we know absolutely nothing - but the future is just waiting to be discovered.
So open your minds and expand past your rest frame for once in your life - you might just learn something amazing...
[nice evening, post cocktail rant. It's just that I get so tired of the directed bickering and blind arguments done to protect egos. It would be nice to see constructive debate without hostility. I'm a writer and this forum definitely provides fodder for my brain - but sadly it's does so by sorting out the personality traits I wish to quell in my own writings...]
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Sorry, but the statements I see on this thread, like with the EM drive thread, crack me up. People post such strongly worded statements on the definite and immutable nature of the physical world around us. Because, you know, we know. Right?
Because, you know, we knew the world was a disk and the heavens above revolved about us.
Until it was proven wrong.
Then of course all was right in the world when Newtonian physics set it all straight. We finally had, literally, conservative physics. And any direction of thought that strayed from these new tenants was blasphemy and the spewers of such treason were dealt with accordingly. But hey, what now do we hear? A particle is a wave? A wave a particle? Where's a cat in a box when a tree falls... quantum leaps of faith?
So now - apparently now - we've got physics all trussed up, flipped over and hog tied. It's now our complete plaything because we've tamed it.
When will we learn - we know nothing in the big picture - hell, we can't even see what the big picture is. So stay in your reference frame and argue the world as you want it perceived, but just take a moment to reflect back into the past and see that we know absolutely nothing - but the future is just waiting to be discovered.
So open your minds and expand past your rest frame for once in your life - you might just learn something amazing...
[nice evening, post cocktail rant. It's just that I get so tired of the directed bickering and blind arguments done to protect egos. It would be nice to see constructive debate without hostility. I'm a writer and this forum definitely provides fodder for my brain - but sadly it's does so by sorting out the personality traits I wish to quell in my own writings...]
Feel free to make any specific suggestions that come to mind. I have been wrong before and will openly consider what you have to say and do my best not to be demeaning. I prefer the sparring back and forth of ideas as it stimulates the imagination and helps me gain over time a visual understanding of what hopefully represents the abstract hidden reality. If two puzzle pieces don't fit together that should, then it is only an interesting clue of something yet to be uncovered. It's not easy to find people to spar with. That's probably what keeps me coming back to this forum.
I speak for myself and others like me. There are some that can come across as rude.
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If you jump around different coordinates in space, via worm-hole or a warp-drive, these paradoxes do no apply. There is no acceleration work being done. You take a patch of space (your ship and then some space around it) from place X and basically "teleport" it to a place Y. Clock speed/rates are NOT affected. Time on board such ships goes at same rate as at the place it started from.
As I have told this to WarpTech repeatedly, the time experienced by the people on board the ship is unrelated to the paradoxes. Unless the existence of the wormhole you used prevents the creation of a wormhole by another ship, it is trivial to implement the paradox.
So technically, A-FTL ships on top of "jumping around" would also have to use regular, relativistic drives to match the target reference frames.
This is not a significant problem, which is why people don't bother discussing it, and irrelevant to paradoxes.
Uh, yes it matters. As in the Twin Paradox, it matters who is the observer and who is changing from the observer time-reference by doing acceleration work. In the A-FTL case there is NO acceleration work being done. Their time remains in-sync regardless of the distance.
Adding a third object traveling at any speed (less than c) through space does not change anything nor opens door to any paradox.
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you are showing here that it's you who do not understand how things work.
your problem lies in thinking you are travelling through 3D space and time is another thing, separate.
Time and space are deeply connected. There is no universal time. So it doesn´t matter you take a bubble of space time with you, if you travelled faster than the speed of causality, you will still may be dropped in a moment of time BEFORE you departed the moment you turn it off.
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yes, it's clear you are not very aware of how light cones and causality works. I posted some videos pages ago. Watch them again and again.
I guess you are the one that failed to understand the difference between relativistic travel through space and the warp drive "idea".
If you travel through space, from initial point X you must do some work to change your time-reference. Relative to some observer left behind at X your clock now ticks differently and you might appear shorter, fine. Yes, travel like that is locked to max of "speed of causality", beyond which things break down, hence no "FTL" through space might be possible, due to all paradoxes it might produce.
FTL "with space" (the Apparent FTL) - for example a warp bubble that moves surrounding space around it-self, does NOT do any acceleration work. The clock ticks EXACTLY at same rate as at the starting point. There are no paradoxes coming out of it. No way to send messages to the past, nothing. A-FTL ship could be here 10:00, next moment jump 1 million ly away from us, spend 5 minutes there, jump back and it would be 10:05 here. This is how it would work (not saying that it will, just how the idea behind it works). Third observer traveling at any speed (less than c, say 0.7c), witnessing that coffee break 1 million ly away, wouldnt be able to send any message back in time to us, as anything he would have sent would arrive at best 1 million years later or if he chose to deliver it in person, about 1.42 million years later (not accounting for the space expansion).
If you fail to see the difference then I have some bad news for you. PS. Next time try to be kinder in your comments.
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FTL "with space" (the Apparent FTL) - for example a warp bubble that moves surrounding space around it-self, does NOT do any acceleration work. The clock ticks EXACTLY at same rate as at the starting point. There are no paradoxes coming out of it. No way to send messages to the past, nothing. A-FTL ship could be here 10:00, next moment jump 1 million ly away from us, spend 5 minutes there, jump back and it would be 10:05 here. This is how it would work (not saying that it will, just how the idea behind it works). Third observer traveling at any speed (less than c, say 0.7c), witnessing that coffee break 1 million ly away, wouldnt be able to send any message back in time to us, as anything he would have sent would arrive at best 1 million years later
The last statement is obviously wrong, since you already presumed that "bubble FTL" is possible. Therefore third observer's message, if sent using "bubble FTL" craft, CAN arrive sooner than 1 million years later.
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It seems to me that I can't affect the local time in the past and create a paradox unless I use a time machine that ignores distance.
Hi sghill, this has been reiterated many times, here is another way of underlining the problem.
How do you define 'simultaneous' between two distant points?
Consider just that. What answer would you come up with?
Here is a very reasonable sounding approach:
* Place a beacon exactly halfway between these to points, A & B.
* The beacon emits a flash of light.
* You claim that the flash arrives at A at the exact same time as it arrives at B.
* Therefore, an instantaneous (ftl) message from A sent when it detects the beacon would be received by b when it detects that beacon.
If you buy that argument you trivially have a paradox, because someone in a different inertial frame will see the light pulse arriving at A and B at different times. They could use one instantaneous communication in their frame of reference to send a message to A, and another also in their frame of reference to get the information back from B before they sent it.
Suffice it to say that it turns out that our really reasonable way of defining simultaneous with a beacon between two points was nonsense.
So how would you define simultaneous?
I wouldn't. "Simultaneous" as a concept between participants doesn't exist except on paper. You can't measure simultaneous between participants because you can't transfer information between the two points simultaneously to actually prove that something occurred at exactly the same moment (that's totally different than proving an event happened simultaneously to a third party observer). Time must pass in order to transfer information between two points separated by distance. I didn't describe FTL communications, I described FTL travel.
E.G., if in 2017 I warp out 100 light years in only 2 years of local time, I've gone back in time 100 years. But it still takes 100 years for me to transmit my radio message of "Oh crap, I just looked through a my ship's big telescope back at the Earth, and Shoeless Joe is cheating at baseball! Don't place your bets on Chicago" to get back to Earth 100 years later (in 2019).
I don't think you have thought through your own description here. You are describing going into the past and then seeing light from the future.
I'm describing going into the observer's future and seeing light from the target's past. THe FTL ship is the observer. Earth is the target. If I warp out a distance, I see Earth's past, but I can't communicate what I see about Earth's past to Earth in the past, I can only communicate what I see of Earth's past to Earth in the present. thus no paradox for FTL ships.
Yes, FTL communications would communicate into the past, but that's not what I'm describing. I'm talking about a ship where the clocks continue forward for the occupants and Earth in the present. When the ship returns from some distance time has passed for both Earth in the present and also the ship. Information transfer to Earth in the past is not possible by the occupants on the ship, they can only observe.
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I didn't describe FTL communications, I described FTL travel.
FTL travel trivially allows FTL communication. This is not a meaningful distinction.
I'm describing going into the observer's future and seeing light from the target's past. THe FTL ship is the observer. Earth is the target. If I warp out a distance, I see Earth's past, but I can't communicate what I see about Earth's past to Earth in the past, I can only communicate what I see of Earth's past to Earth in the present. thus no paradox for FTL ships.
None of what you are describing has any relation to the paradoxes. Go read the first 2 pages of the thread, at least through the worked examples.
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FTL "with space" (the Apparent FTL) - for example a warp bubble that moves surrounding space around it-self, does NOT do any acceleration work. The clock ticks EXACTLY at same rate as at the starting point. There are no paradoxes coming out of it. No way to send messages to the past, nothing. A-FTL ship could be here 10:00, next moment jump 1 million ly away from us, spend 5 minutes there, jump back and it would be 10:05 here. This is how it would work (not saying that it will, just how the idea behind it works). Third observer traveling at any speed (less than c, say 0.7c), witnessing that coffee break 1 million ly away, wouldnt be able to send any message back in time to us, as anything he would have sent would arrive at best 1 million years later
The last statement is obviously wrong, since you already presumed that "bubble FTL" is possible. Therefore third observer's message, if sent using "bubble FTL" craft, CAN arrive sooner than 1 million years later.
If you read again, carefully this time, you would notice I said that ship can't do it, not that it's not possible. Said ship is traveling at 0.7C while passing by the coffee break event. Said ship can only keep flying at 0.7C in our direction or send some message at speed=C at best. So a message can arrive, again, at best in 1 million years after the coffee break took place, or 1.42million years later if delivered in person by the crew of said observer ship (ignoring space expansion).
That being said, why are you arguing over such tiny details? Do you like arguing for no reason? :) Trying to nitpick something someone said to point out possible statement error doesn't look good.
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If you jump around different coordinates in space, via worm-hole or a warp-drive, these paradoxes do no apply. There is no acceleration work being done. You take a patch of space (your ship and then some space around it) from place X and basically "teleport" it to a place Y. Clock speed/rates are NOT affected. Time on board such ships goes at same rate as at the place it started from.
As I have told this to WarpTech repeatedly, the time experienced by the people on board the ship is unrelated to the paradoxes. Unless the existence of the wormhole you used prevents the creation of a wormhole by another ship, it is trivial to implement the paradox.
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Uh, yes it matters. As in the Twin Paradox, it matters who is the observer and who is changing from the observer time-reference by doing acceleration work. In the A-FTL case there is NO acceleration work being done. Their time remains in-sync regardless of the distance.
Adding a third object traveling at any speed (less than c) through space does not change anything nor opens door to any paradox.
Go read the descriptions of the paradox inducing situations early in this thread. The amount of time experienced by the people travelling does not matter. Keep rereading the descriptions until you get that, because if you still think otherwise you have not understood them. If you build a wormhole/warp bubble that takes you 100 light years away in 1 year (so that when you arrive you see light from 99 years before you left) but gravitational time dilation as you pass through makes you age 1000 years, this does not change the paradox. The additional object travelling at a different speed using its FTL can leave after you arrive, and arrive before you left.
FTL "with space" (the Apparent FTL) - for example a warp bubble that moves surrounding space around it-self, does NOT do any acceleration work. The clock ticks EXACTLY at same rate as at the starting point. There are no paradoxes coming out of it. No way to send messages to the past, nothing. A-FTL ship could be here 10:00, next moment jump 1 million ly away from us, spend 5 minutes there, jump back and it would be 10:05 here. This is how it would work (not saying that it will, just how the idea behind it works). Third observer traveling at any speed (less than c, say 0.7c), witnessing that coffee break 1 million ly away, wouldnt be able to send any message back in time to us, as anything he would have sent would arrive at best 1 million years later
The last statement is obviously wrong, since you already presumed that "bubble FTL" is possible. Therefore third observer's message, if sent using "bubble FTL" craft, CAN arrive sooner than 1 million years later.
If you read again, carefully this time, you would notice I said that ship can't do it, not that it's not possible. Said ship is traveling at 0.7C while passing by the coffee break event. Said ship can only keep flying at 0.7C in our direction or send some message at speed=C at best. So a message can arrive, again, at best in 1 million years after the coffee break took place, or 1.42million years later if delivered in person by the crew of said observer ship (ignoring space expansion).
That being said, why are you arguing over such tiny details? Do you like arguing for no reason? :) Trying to nitpick something someone said to point out possible statement error doesn't look good.
He is not nitpicking a tiny detail, and you did not seem to even understand what he said.
The other ship also would have FTL capability.
"Said ship can only keep flying at 0.7C in our direction or send some message at speed=C at best"
This sentence ignores the 3rd option that the other ship uses its own FTL. Using its own FTL will result in it travelling to the distant past on Earth because it has a different definition of simultaneous.
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I didn't describe FTL communications, I described FTL travel.
FTL travel trivially allows FTL communication. This is not a meaningful distinction.
I'm describing going into the observer's future and seeing light from the target's past. THe FTL ship is the observer. Earth is the target. If I warp out a distance, I see Earth's past, but I can't communicate what I see about Earth's past to Earth in the past, I can only communicate what I see of Earth's past to Earth in the present. thus no paradox for FTL ships.
None of what you are describing has any relation to the paradoxes. Go read the first 2 pages of the thread, at least through the worked examples.
Why FTL is even discussed at this point, of course any FTL transmission would travel back in time, math supports it, diagrams support it, experiments, well, do not support it as we are not sure how to make one. No need any third observer to prove/discover paradoxes. I'm talking about FTL through space of course.
Side note: Speaking of FTL experimentation, wave-function collapse problem, quantum effects etc., perhaps there is a way to construct an experiment that encapsulates some time-loop event but we only learn its outcome afterwards? (where causality is not broken/threatened). Some setup that would allow to prove that some particle went back in time, and changed state of something before it was used, but in such way that it would be impossible for us to act upon said change of state? For example (simplified/layman version): Blackbox where dice is dropped, regardless of its result, an event A is executed if the number is odd, event B of it's even. At the same time, before dice touches the ground, event C is executed. Event A is a light sent through A slit inside the Blackbox onto a detector. Event B is null, no light being sent. Event C is light sent through slit B inside the Blackbox onto a detector. Everything is recorded and available only after the experiment took place. Expected result, perhaps after 1000's of tries, would show some slight interference pattern being detected? This of course is just simple double-slit event experiment. Perhaps there are some other events that are suspected to produce particles that could possibly go back in time, and base the Blackbox setup on that. Anyway, general idea is to make a setup where event A or B happens regardless of C and A B C take place before ANY action can be made by observers.
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If you jump around different coordinates in space, via worm-hole or a warp-drive, these paradoxes do no apply. There is no acceleration work being done. You take a patch of space (your ship and then some space around it) from place X and basically "teleport" it to a place Y. Clock speed/rates are NOT affected. Time on board such ships goes at same rate as at the place it started from.
As I have told this to WarpTech repeatedly, the time experienced by the people on board the ship is unrelated to the paradoxes. Unless the existence of the wormhole you used prevents the creation of a wormhole by another ship, it is trivial to implement the paradox.
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Uh, yes it matters. As in the Twin Paradox, it matters who is the observer and who is changing from the observer time-reference by doing acceleration work. In the A-FTL case there is NO acceleration work being done. Their time remains in-sync regardless of the distance.
Adding a third object traveling at any speed (less than c) through space does not change anything nor opens door to any paradox.
Go read the descriptions of the paradox inducing situations early in this thread. The amount of time experienced by the people travelling does not matter. Keep rereading the descriptions until you get that, because if you still think otherwise you have not understood them. If you build a wormhole/warp bubble that takes you 100 light years away in 1 year (so that when you arrive you see light from 99 years before you left) but gravitational time dilation as you pass through makes you age 1000 years, this does not change the paradox. The additional object travelling at a different speed using its FTL can leave after you arrive, and arrive before you left.
FTL "with space" (the Apparent FTL) - for example a warp bubble that moves surrounding space around it-self, does NOT do any acceleration work. The clock ticks EXACTLY at same rate as at the starting point. There are no paradoxes coming out of it. No way to send messages to the past, nothing. A-FTL ship could be here 10:00, next moment jump 1 million ly away from us, spend 5 minutes there, jump back and it would be 10:05 here. This is how it would work (not saying that it will, just how the idea behind it works). Third observer traveling at any speed (less than c, say 0.7c), witnessing that coffee break 1 million ly away, wouldnt be able to send any message back in time to us, as anything he would have sent would arrive at best 1 million years later
The last statement is obviously wrong, since you already presumed that "bubble FTL" is possible. Therefore third observer's message, if sent using "bubble FTL" craft, CAN arrive sooner than 1 million years later.
If you read again, carefully this time, you would notice I said that ship can't do it, not that it's not possible. Said ship is traveling at 0.7C while passing by the coffee break event. Said ship can only keep flying at 0.7C in our direction or send some message at speed=C at best. So a message can arrive, again, at best in 1 million years after the coffee break took place, or 1.42million years later if delivered in person by the crew of said observer ship (ignoring space expansion).
That being said, why are you arguing over such tiny details? Do you like arguing for no reason? :) Trying to nitpick something someone said to point out possible statement error doesn't look good.
He is not nitpicking a tiny detail, and you did not seem to even understand what he said.
The other ship also would have FTL capability.
"Said ship can only keep flying at 0.7C in our direction or send some message at speed=C at best"
This sentence ignores the 3rd option that the other ship uses its own FTL. Using its own FTL will result in it travelling to the distant past on Earth because it has a different definition of simultaneous.
What third option? I clearly said that observer ship travels at 0.7c. If it had FTL, it would be different, but I said it's 0.7c so why make up options? And I used 0.7c because it was the speed I believe you used yourself in some of the examples. I did understand what he said perfectly.
At school exam, when teacher tasked you to solve some task, where "train goes at 100km/h and ...", did you also try to be smart and say "yeah but it could also go at 120km/h!", sure it could, but that's not the case in situation you've been tasked with, so no point in making such option(s).
Next, I do understand what you said about the observer traveling at 0.7c by the coffee event and THEN using the bubble FTL to go to us. Yes, his bubble encapsulates different time-reference, but the moment he switches off the A-FTL, everything will move away from him at 0.7c. Any message sent will be delayed a bit, and that bit happens to be exactly what would prevent him from sending a message back in time, even by a tiny bit.
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I didn't describe FTL communications, I described FTL travel.
FTL travel trivially allows FTL communication. This is not a meaningful distinction.
I'm describing going into the observer's future and seeing light from the target's past. THe FTL ship is the observer. Earth is the target. If I warp out a distance, I see Earth's past, but I can't communicate what I see about Earth's past to Earth in the past, I can only communicate what I see of Earth's past to Earth in the present. thus no paradox for FTL ships.
None of what you are describing has any relation to the paradoxes. Go read the first 2 pages of the thread, at least through the worked examples.
Why FTL is even discussed at this point, of course any FTL transmission would travel back in time, math supports it, diagrams support it, experiments, well, do not support it as we are not sure how to make one. No need any third observer to prove/discover paradoxes. I'm talking about FTL through space of course.
No, actually. I am aware of no situation where a single FTL event (travel or just a message makes no difference) can result in a paradox. Either their needs to be another ship/ansible/whatever travelling at a different velocity, or the first one needs to chane its velocity and then do its FTL thing again.
Your misuse of "Apparent FTL" does not change this. Warp bubbles and wormholes still have the same problems with FTL.
Also, as to your whole sidenote, it has been experimentally demonstrated repeatedly. Look up tests of Bell's inequality, which demonstrate that quantum mechanics is without a doubt non-local, but in a way that can't transmit useful information, so it can't break causality.
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What third option? I clearly said that observer ship travels at 0.7c. If it had FTL, it would be different, but I said it's 0.7c so why make up options? And I used 0.7c because it was the speed I believe you used yourself in some of the examples. I did understand what he said perfectly.
At school exam, when teacher tasked you to solve some task, where "train goes at 100km/h and ...", did you also try to be smart and say "yeah but it could also go at 120km/h!", sure it could, but that's not the case in situation you've been tasked with, so no point in making such option(s).
Next, I do understand what you said about the observer traveling at 0.7c by the coffee event and THEN using the bubble FTL to go to us. Yes, his bubble encapsulates different time-reference, but the moment he switches off the A-FTL, everything will move away from him at 0.7c. Any message sent will be delayed a bit, and that bit happens to be exactly what would prevent him from sending a message back in time, even by a tiny bit.
You trying to say "but the other ship doesn't have FTL" is simply a poor attempt at avoiding the issue. Ignoring situations that cause paradoxes don't make them go away.
No, no significant delay would happen, they would choose their exit point properly, and depending on the setup could end up many years in the past from Earth's perspective. Go look at the worked examples from the beginning of this thread.
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There are I think three possible resolutions to FTL paradoxes:
1. FTL is possible but there is no communication possible with the outside world until the light cone has caught up. So for instance, you jump 1 ly away, but then cannot communicate (in any way, in either direction) with the outside world for a year. Although this at first seems a bit pointless, it would allow light speed travel, which is much better than we can do now.
2. FTL travel moves you into a parallel universe, no paradoxes are possible within that stack of universes. Perhaps you could return to your own universe/origin, but only if no paradoxes have been created in any frame of reference.
3. Paradoxes are not possible because of some unknown physical principle. Although we can create paradoxes with thought experiments, this unknown principle means that those thought experiments cannot be realized.
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What third option? I clearly said that observer ship travels at 0.7c. If it had FTL, it would be different, but I said it's 0.7c so why make up options? And I used 0.7c because it was the speed I believe you used yourself in some of the examples. I did understand what he said perfectly.
At school exam, when teacher tasked you to solve some task, where "train goes at 100km/h and ...", did you also try to be smart and say "yeah but it could also go at 120km/h!", sure it could, but that's not the case in situation you've been tasked with, so no point in making such option(s).
Next, I do understand what you said about the observer traveling at 0.7c by the coffee event and THEN using the bubble FTL to go to us. Yes, his bubble encapsulates different time-reference, but the moment he switches off the A-FTL, everything will move away from him at 0.7c. Any message sent will be delayed a bit, and that bit happens to be exactly what would prevent him from sending a message back in time, even by a tiny bit.
You trying to say "but the other ship doesn't have FTL" is simply a poor attempt at avoiding the issue. Ignoring situations that cause paradoxes don't make them go away.
No, no significant delay would happen, they would choose their exit point properly, and depending on the setup could end up many years in the past from Earth's perspective. Go look at the worked examples from the beginning of this thread.
No, I was just pointing out that making such case was not the point of given example. Now, like I said later on, even if that observer ship used bubble FTL, it would result in no paradoxes at all.
Let me make it more clear to you, the moment such ship a million ly away witnesses the coffee break event, no matter what speed it is traveling at, its reference frame is counting time FROM that moment onwards, and since the ship is not moving faster than light through space, it cannot travel backwards in time. Lets make a timeline:
1) Ship1 leaves point X at 10:00, travels for 10 minutes 1 million light years away to point Y, where at 10:10 has a 5 min coffee break until 10:15, jumps back, 10minutes later arrives back at point X, its now 10:25.
2) Ship2 was passing by point Y at 0.99c, saw coffee break event, due to his speed, the event appeared to be shorter, taking only 1 minute (5x less).
3) Ship2 decided to use a similar bubble FTL engine like on Ship1, and in his 10 minutes of time, arrived at point X.
4) Ship2 time-reference being different, made the travel shorter, so after the coffee break event was over, it traveled to X in 10/5=2minutes of time instead of 10 minutes like Ship1. Ship2 arrived at point X at 10:17.
That being said, we are making a big assumption for "warp bubbles", such that space it self has no volume, for example, perhaps, warping at 0.7c to from Y to X is 1.42 times more energy-consuming, hence in reality the drive was just working that much harder to arrive there in 2 minutes instead of 10. I guess we might never know. However, it is irrelevant to the problems within this thread. There are no paradoxes with Apparent FTL.
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Let me make it more clear to you, the moment such ship a million ly away witnesses the coffee break event, no matter what speed it is traveling at, its reference frame is counting time FROM that moment onwards, and since the ship is not moving faster than light through space, it cannot travel backwards in time. Lets make a timeline:
1) Ship1 leaves point X at 10:00, travels for 10 minutes 1 million light years away to point Y, where at 10:10 has a 5 min coffee break until 10:15, jumps back, 10minutes later arrives back at point X, its now 10:25.
2) Ship2 was passing by point Y at 0.99c, saw coffee break event, due to his speed, the event appeared to be shorter, taking only 1 minute (5x less).
3) Ship2 decided to use a similar bubble FTL engine like on Ship1, and in his 10 minutes of time, arrived at point X.
4) Ship2 time-reference being different, made the travel shorter, so after the coffee break event was over, it traveled to X in 10/5=2minutes of time instead of 10 minutes like Ship1. Ship2 arrived at point X at 10:17.
Mostly fine up until step 4.
There is no absolute time reference, so ship 2 would arrive some hundreds of thousands of years before ship 1 originally left point X.
Did you read the examples I worked out at the beginning of this thread yet?
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Let me make it more clear to you, the moment such ship a million ly away witnesses the coffee break event, no matter what speed it is traveling at, its reference frame is counting time FROM that moment onwards, and since the ship is not moving faster than light through space, it cannot travel backwards in time. Lets make a timeline:
1) Ship1 leaves point X at 10:00, travels for 10 minutes 1 million light years away to point Y, where at 10:10 has a 5 min coffee break until 10:15, jumps back, 10minutes later arrives back at point X, its now 10:25.
2) Ship2 was passing by point Y at 0.99c, saw coffee break event, due to his speed, the event appeared to be shorter, taking only 1 minute (5x less).
3) Ship2 decided to use a similar bubble FTL engine like on Ship1, and in his 10 minutes of time, arrived at point X.
4) Ship2 time-reference being different, made the travel shorter, so after the coffee break event was over, it traveled to X in 10/5=2minutes of time instead of 10 minutes like Ship1. Ship2 arrived at point X at 10:17.
Mostly fine up until step 4.
There is no absolute time reference, so ship 2 would arrive some hundreds of thousands of years before ship 1 originally left point X.
Did you read the examples I worked out at the beginning of this thread yet?
It would not, as it started witnessing the event at lets call it TIME_X, from which, their respective clocks continue ticking onwards but at different rates. At TIME_X, the events such as Ship1 leaving the point X have already happened, regardless of any time-reference frame. Doesn't matter at what speed Ship2 is traveling at through space, it cannot revisit that time/space coordinate anymore without breaking causality (via traveling FTL through-space for example). It is traveling FTL using a warp bubble, without ever going beyond C in space. It makes a huge difference.
Let me put it in a different way - just because Ship2 can see the event, it means the event of Ship1 leaving point X has already happened, even in time reference of Ship2. Ship2 is not a time traveler, no matter how fast it will go to point X, it will not arrive there before Ship1 has left.
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It would not, as it started witnessing the event at lets call it TIME_X, from which, their respective clocks continue ticking onwards but at different rates. At TIME_X, the events such as Ship1 leaving the point X have already happened, regardless of any time-reference frame.
This is simply false, the event that ship 1 left point X happens a long time in the future according to someone at the coffee break travelling with some velocity relative to ship 1.
Doesn't matter at what speed Ship2 is traveling at through space, it cannot revisit that time/space coordinate anymore without breaking causality (via traveling FTL through-space for example). It is traveling FTL using a warp bubble, without ever going beyond C in space. It makes a huge difference.
It makes no difference whatsoever. All that matters are the events in spacetime (each ship departing/arriving). What method they used to FTL is irrelevant. The breaking of causality would happen with any form of FTL including wormholes.
Let me put it in a different way - just because Ship2 can see the event, it means the event of Ship1 leaving point X has already happened, even in time reference of Ship2. Ship2 is not a time traveler, no matter how fast it will go to point X, it will not arrive there before Ship1 has left.
FTL of any sort is time travel, and it is simply inconsistent with relativity to make the claim that the ship 1 leaving is an event that had already happened in the ship 2 frame.
You still appear to have not read the examples I already provided, after repeated requests for you to do so. At this point not doing so is extremely rude. You seem to be new here, so you might not know this, but moderators don't appreciate rudeness here, so if you continue trying to communicate with me without going back to read the examples I worked out, you can expect your posts to disappear.
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It would not, as it started witnessing the event at lets call it TIME_X, from which, their respective clocks continue ticking onwards but at different rates. At TIME_X, the events such as Ship1 leaving the point X have already happened, regardless of any time-reference frame.
This is simply false, the event that ship 1 left point X happens a long time in the future according to someone at the coffee break travelling with some velocity relative to ship 1.
Uh, stop right here. That's not true and there is no math that could back this up. When you SEE the event-B (coffee break) that is an outcome of an event-A happening (Ship1 leaving point X), it means, logically, that regardless of your speed, event-A is already in your past. Sorry man, that's how causality works.
Edit: To publicly address some private note - no, I don't feel like I'm doing a logical fallacy here, proving causality isn't broken by assuming it cannot be broken, no.
I think we all agree causality is pretty much broken the moment something could move faster than the causality speed (lets just say c) through space. That is why it is called causality speed after all. Now, with Apparent FTL, where we do not move faster than c through space, logically, do not break causality. If we see a star explosion on the sky, do an instant FTL jump there, we would still arrive X (=ly distance) many years after the event, not a day before, not a day after (ignoring space expansion here). If someone witnessed our visit, while moving at some relativistic speed, and did an FTL jump back with us, would still arrive after we have left to see it, it's that simple.
PS. Yes I have read your examples, they are inadequate IMO. Just to point out some error, Observer1 at A sees distance from A to B to be 10ly, Observer2, traveling at relativistic speed of 0.7c passing A towards B would tell its a different distance; and to him, it would be. It is how relativity works. You ignored that completely in your calculations.
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It would not, as it started witnessing the event at lets call it TIME_X, from which, their respective clocks continue ticking onwards but at different rates. At TIME_X, the events such as Ship1 leaving the point X have already happened, regardless of any time-reference frame.
This is simply false, the event that ship 1 left point X happens a long time in the future according to someone at the coffee break travelling with some velocity relative to ship 1.
Uh, stop right here. That's not true and there is no math that could back this up. When you SEE the event-B (coffee break) that is an outcome of an event-A happening (Ship1 leaving point X), it means, logically, that regardless of your speed, event-A is already in your past. Sorry man, that's how causality works.
Edit: To publicly address some private note - no, I don't feel like I'm doing a logical fallacy here, proving causality isn't broken by assuming it cannot be broken, no.
This directly is circular logic, or "begging the question." You are saying that ship 1 leaving must be in the past because of causality, therefore causality is preserved.
I think we all agree causality is pretty much broken the moment something could move faster than the causality speed (lets just say c) through space. That is why it is called causality speed after all.
No, no one including me has been able to come up with an example of causality breaking from a single FTL jump. If you can, please share.
Now, with Apparent FTL, where we do not move faster than c through space, logically, do not break causality. If we see a star explosion on the sky, do an instant FTL jump there, we would still arrive X (=ly distance) many years after the event, not a day before, not a day after (ignoring space expansion here). If someone witnessed our visit, while moving at some relativistic speed, and did an FTL jump back with us, would still arrive after we have left to see it, it's that simple.
Your last sentence is simply wrong, and ignores that in the reference frame of the other ship, the event of the first ship leaving can be in the future, because it is a spacelike separated event. This means that it can jump back to before the first ship left.
PS. Yes I have read your examples, they are inadequate IMO. Just to point out some error, Observer1 at A sees distance from A to B to be 10ly, Observer2, traveling at relativistic speed of 0.7c passing A towards B would tell its a different distance; and to him, it would be. It is how relativity works. You ignored that completely in your calculations.
I explicitly remember showing that effect, and I always accounted for it, because it is built directly into the Lorentz transformations. Please point me to the post where you think I didn't. (Right click on the post title and copy link, or just quote the post, which creates a link)
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Now, with Apparent FTL, where we do not move faster than c through space, logically, do not break causality. If we see a star explosion on the sky, do an instant FTL jump there, we would still arrive X (=ly distance) many years after the event, not a day before, not a day after (ignoring space expansion here). If someone witnessed our visit, while moving at some relativistic speed, and did an FTL jump back with us, would still arrive after we have left to see it, it's that simple.
Your last sentence is simply wrong, and ignores that in the reference frame of the other ship, the event of the first ship leaving can be in the future, because it is a spacelike separated event. This means that it can jump back to before the first ship left.
Again, if ship2 witnessed the event-B, then regardless of its reference frame, event-A must be in its past. Cannot be in the future.
Let's dig deeper. Lets say Oberserver 1 clock ticks 1time for 1min, its current tick count at event-A is 1000, at event-B is 1010. Journey home, clock is at 1025 (after 5 ticks for coffee break).
Observer 2 clock is ticking way slower, relatively to Observer 1, let's just say it's been like that forever. At the event-A, Observer2's clock is at 200, and at 202 when event-B starts. This conjunction of 2 different clocks running at different rates happens when event-B occurs. Now, Observer 2, watches the event, which is 1 tick long to him then takes 2 ticks of his clock to travel the distance of points Y->X. Arrives at point X on tick 205, while to point X Observers, Observer2 arrives at tick 1025. They both arrive at the same time.
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Again, if ship2 witnessed the event-B, then regardless of its reference frame, event-A must be in its past. Cannot be in the future.
Again, this is simply inconsistent with the Lorentz transforms that underlie special relativity. If A and B are spacelike separated events you can always find a reference frame in which they occur in whatever order you choose. FTL travel is by definition travel between spacelike separated events.
Let's dig deeper. Lets say Oberserver 1 clock ticks 1time for 1min, its current tick count at event-A is 1000, at event-B is 1010. Journey home, clock is at 1025 (after 5 ticks for coffee break).
Observer 2 clock is ticking way slower, relatively to Observer 1, let's just say it's been like that forever. At the event-A, Observer2's clock is at 200, and at 202 when event-B starts.
This is wrong. You have already defined the situation to be inconsistent with special relativity. The time of events A and B in frame 2 need to be calculated using the Lorentz transformations, which take into account the distance between the events.
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There are I think three possible resolutions to FTL paradoxes:
1. FTL is possible but there is no communication possible with the outside world until the light cone has caught up. So for instance, you jump 1 ly away, but then cannot communicate (in any way, in either direction) with the outside world for a year. Although this at first seems a bit pointless, it would allow light speed travel, which is much better than we can do now.
2. FTL travel moves you into a parallel universe, no paradoxes are possible within that stack of universes. Perhaps you could return to your own universe/origin, but only if no paradoxes have been created in any frame of reference.
3. Paradoxes are not possible because of some unknown physical principle. Although we can create paradoxes with thought experiments, this unknown principle means that those thought experiments cannot be realized.
Probably number 3. Any instant jump would probably have to be with respect to a rest frame, not a relativistic one. This kind of jump would be independent from relativity.
Where you run into problems with jumping instantaneously from point to point is energy/momentum conservation. If FTL is possible then it probably isn't instantaneous jumps from point to point.
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2. FTL travel moves you into a parallel universe, no paradoxes are possible within that stack of universes. Perhaps you could return to your own universe/origin, but only if no paradoxes have been created in any frame of reference.
I just wanted to comment on this case. It may be weirder than you think.
Im going to ignore the possibility of slipping back to your previous universe. In that case you just have 3:
3. Paradoxes are not possible because of some unknown physical principle. Although we can create paradoxes with thought experiments, this unknown principle means that those thought experiments cannot be realized.
(ie some other as yet unspecified solution to FTL.)
If you don't have 3 then you just have branching universes as a solution to FTL and time travel in general. You can go back in time and murder your grandfather, no problem. From your POV your history and memory is uninterrupted. From the POV of your destination universe you are just a stranger.
The weirdness is, I think you are now in a scenario where non-travellers do not see people performing FTL, ie beginning a voyage at A and reappearing at B. Like the grandfather killer, anyone that appears is a stranger.
Im not sure if you would have a situation where
(a) there was often a similarity between the person who began the voyage and the person who returns, and only sometimes no similarity at all, as in the grandfather killer who was never born, or
(b) whether you would have branching universes who only ever experienced one successful-ish FTL flight returnee, namely you, and all other FTL flights simply vanish to some other universe, never to return. The travellers might experience a typical star-hopping experience, but every universe they arrived in would see them as absolutely unique, and no universe would bother to have an FTL economy because no one comes back.
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Side note: Speaking of FTL experimentation, wave-function collapse problem, quantum effects etc., perhaps there is a way to construct an experiment that encapsulates some time-loop event but we only learn its outcome afterwards? (where causality is not broken/threatened). Some setup that would allow to prove that some particle went back in time, and changed state of something before it was used, but in such way that it would be impossible for us to act upon said change of state? For example (simplified/layman version): Blackbox where dice is dropped, regardless of its result, an event A is executed if the number is odd, event B of it's even. At the same time, before dice touches the ground, event C is executed. Event A is a light sent through A slit inside the Blackbox onto a detector. Event B is null, no light being sent. Event C is light sent through slit B inside the Blackbox onto a detector. Everything is recorded and available only after the experiment took place. Expected result, perhaps after 1000's of tries, would show some slight interference pattern being detected? This of course is just simple double-slit event experiment. Perhaps there are some other events that are suspected to produce particles that could possibly go back in time, and base the Blackbox setup on that. Anyway, general idea is to make a setup where event A or B happens regardless of C and A B C take place before ANY action can be made by observers.
Been done.
https://www.nbcnews.com/science/weird-science/great-scott-reverse-causality-experiment-ends-quantum-muddle-n336766
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Please play nice. Polite questions and answers are the soul of NSF. If we wanted romper room, we'd take it to Reddit.
Play nice? First post in the forum and the guy comes treating everyone as morons. He didn´t read a single page of this thread. Just comes and say "it's all a big misunderstanding" and the proceeds to say a lot of things already talked and debunked before here. Says we are confused and thinks he cleared things up when we have been talking about those same things the past 12 pages!
Your first post in the forum, thinking you are wiser than everyone else while not even attempting to read past pages: THAT is what is not playing nice.
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Suppose we have solved the grandfather paradoxes, (eg by using the rule that the CMB temperature cannot be hotter at your destination, ie the universe cannot be 'younger')
Is it possible for mass to just vanish at one point and appear at another without violating any conservation law?
I just thought of a possible problem: You would have jumped back in time from some frames of reference even if you have avoided grandfather paradoxes. Does this mean that from THAT frame of reference there are two of you existing simultaneously? and there is more mass in the universe, more gravity and so on?
(In the worst case, I think you could solve these conservation issues by your 'stargate' having some sort of mass that you add to when you enter and subtract from when you exit, but it might put a damper on 'warp travel' style FTL.)
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Please play nice. Polite questions and answers are the soul of NSF. If we wanted romper room, we'd take it to Reddit.
Play nice? First post in the forum and the guy comes treating everyone as morons. He didn´t read a single page of this thread. Just comes and say "it's all a big misunderstanding" and the proceeds to say a lot of things already talked and debunked before here. Says we are confused and thinks he cleared things up when we have been talking about those same things the past 12 pages!
Your first post in the forum, thinking you are wiser than everyone else while not even attempting to read past pages: THAT is what is not playing nice.
I did read all pages before posting, and the only viable option to me was that there is some misunderstanding of what WarpTech had in mind and what was being debated.
Nothing what I said was debunked, how can you debunk something related to FTL or A-FTL if we have neither to put on to a test? We can only speculate and there is a disagreement, that's all to it.
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Again, if ship2 witnessed the event-B, then regardless of its reference frame, event-A must be in its past. Cannot be in the future.
Again, this is simply inconsistent with the Lorentz transforms that underlie special relativity. If A and B are spacelike separated events you can always find a reference frame in which they occur in whatever order you choose. FTL travel is by definition travel between spacelike separated events.
Let's dig deeper. Lets say Oberserver 1 clock ticks 1time for 1min, its current tick count at event-A is 1000, at event-B is 1010. Journey home, clock is at 1025 (after 5 ticks for coffee break).
Observer 2 clock is ticking way slower, relatively to Observer 1, let's just say it's been like that forever. At the event-A, Observer2's clock is at 200, and at 202 when event-B starts.
This is wrong. You have already defined the situation to be inconsistent with special relativity. The time of events A and B in frame 2 need to be calculated using the Lorentz transformations, which take into account the distance between the events.
That's a small detail. Given what you've said, if there was no Ship2 (Observer2), but Ship1 had ability to quickly accelerate to 0.7c, and jump back to Point X, he would end up in its past. Why? Because if there was a Ship2 and saw the event while going at 0.7c, and after event took place, just waited a short while, during which Ship1 matched it speed of 0.7c, and then they both jumped back to point X, they would end up at point X at the same time in space, which wouldn't be in the past by the way.
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https://www.youtube.com/watch?v=msVuCEs8Ydo
This is a great primer for what the Lorentz Transformations are, and what the Speed of Light actually is.
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Again, if ship2 witnessed the event-B, then regardless of its reference frame, event-A must be in its past. Cannot be in the future.
Again, this is simply inconsistent with the Lorentz transforms that underlie special relativity. If A and B are spacelike separated events you can always find a reference frame in which they occur in whatever order you choose. FTL travel is by definition travel between spacelike separated events.
Let's dig deeper. Lets say Oberserver 1 clock ticks 1time for 1min, its current tick count at event-A is 1000, at event-B is 1010. Journey home, clock is at 1025 (after 5 ticks for coffee break).
Observer 2 clock is ticking way slower, relatively to Observer 1, let's just say it's been like that forever. At the event-A, Observer2's clock is at 200, and at 202 when event-B starts.
This is wrong. You have already defined the situation to be inconsistent with special relativity. The time of events A and B in frame 2 need to be calculated using the Lorentz transformations, which take into account the distance between the events.
That's a small detail.
Consistency with the theory of relativity is not a "small detail"
Given what you've said, if there was no Ship2 (Observer2), but Ship1 had ability to quickly accelerate to 0.7c, and jump back to Point X, he would end up in its past. Why? Because if there was a Ship2 and saw the event while going at 0.7c, and after event took place, just waited a short while, during which Ship1 matched it speed of 0.7c, and then they both jumped back to point X, they would end up at point X at the same time in space,
Yes if Ship 1 had the ability to quickly accelerate to 0.7 c, it could make a jump and end up in its own past. This is an unavoidable consequence of special relativity + FTL (of any sort).
which wouldn't be in the past by the way.
I already did the math that demonstrates that this would very much be in ship 1's past. Do you have any specific disputes with that math?
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Again, if ship2 witnessed the event-B, then regardless of its reference frame, event-A must be in its past. Cannot be in the future.
Again, this is simply inconsistent with the Lorentz transforms that underlie special relativity. If A and B are spacelike separated events you can always find a reference frame in which they occur in whatever order you choose. FTL travel is by definition travel between spacelike separated events.
Let's dig deeper. Lets say Oberserver 1 clock ticks 1time for 1min, its current tick count at event-A is 1000, at event-B is 1010. Journey home, clock is at 1025 (after 5 ticks for coffee break).
Observer 2 clock is ticking way slower, relatively to Observer 1, let's just say it's been like that forever. At the event-A, Observer2's clock is at 200, and at 202 when event-B starts.
This is wrong. You have already defined the situation to be inconsistent with special relativity. The time of events A and B in frame 2 need to be calculated using the Lorentz transformations, which take into account the distance between the events.
That's a small detail.
Consistency with the theory of relativity is not a "small detail"
Given what you've said, if there was no Ship2 (Observer2), but Ship1 had ability to quickly accelerate to 0.7c, and jump back to Point X, he would end up in its past. Why? Because if there was a Ship2 and saw the event while going at 0.7c, and after event took place, just waited a short while, during which Ship1 matched it speed of 0.7c, and then they both jumped back to point X, they would end up at point X at the same time in space,
Yes if Ship 1 had the ability to quickly accelerate to 0.7 c, it could make a jump and end up in its own past. This is an unavoidable consequence of special relativity + FTL (of any sort).
which wouldn't be in the past by the way.
I already did the math that demonstrates that this would very much be in ship 1's past. Do you have any specific disputes with that math?
I'll bite. Please provide math that supports this short story:
1. Ship uses A-FTL to (instantly) jump 100 light years away from point X, to point Y
2. At point Y, accelerates to 0.7c (instantly)
3. Ship uses A-FTL to jump (instantly) back from point Y to point X, ends up in its own past.
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I already did the math that demonstrates that this would very much be in ship 1's past. Do you have any specific disputes with that math?
I'll bite. Please provide math that supports this short story:
1. Ship uses A-FTL to (instantly) jump 100 light years away from point X, to point Y
2. At point Y, accelerates to 0.7c (instantly)
3. Ship uses A-FTL to jump (instantly) back from point Y to point X, ends up in its own past.
What part of "already did the math" did you not understand?
You claimed that you had read my posts with math from the beginning of the thread.
Here is a link to one that answers basically the same scenario, except with only 10 light years, and allowing 5 weeks travel time instead of instantaneous. Ship 2 in that scenario is exactly equivalent to a ship 1 that accelerates rapidly to match ship 2's speed. Instantaneous travel and larger distance only make the amount of time travel larger.
(Top of the quote is a link back to the full post)
Let me break it down with numbers. Define that Ship 1 is at rest in the Earth frame at t= 0, x = 0. At this time ship 1 activates its FTL drive, allowing it to arrive at a location in the earth frame of x = 10 light years, at time t = 5 weeks, (apparent speed of roughly 100 c). ...
Contrary to one of your previous posts where you claimed that I didn't account for length contraction, you can see in that post where I explicitly listed the length contracted distance to Earth.
PS. Yes I have read your examples, they are inadequate IMO. Just to point out some error, Observer1 at A sees distance from A to B to be 10ly, Observer2, traveling at relativistic speed of 0.7c passing A towards B would tell its a different distance; and to him, it would be. It is how relativity works. You ignored that completely in your calculations.
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https://www.youtube.com/watch?v=msVuCEs8Ydo
This is a great primer for what the Lorentz Transformations are, and what the Speed of Light actually is.
yeah, I also posted these two other videos that specifically talk about superluminal travel... Kamill says he read the whole thread, but I think he skipped these videos
https://www.youtube.com/watch?v=1YFrISfN7jo
https://www.youtube.com/watch?time_continue=646&v=HUMGc8hEkpc
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https://www.youtube.com/watch?v=msVuCEs8Ydo
This is a great primer for what the Lorentz Transformations are, and what the Speed of Light actually is.
yeah, I also posted these two other videos that specifically talk about superluminal travel... Kamill says he read the whole thread, but I think he skipped these videos
https://www.youtube.com/watch?v=1YFrISfN7jo
https://www.youtube.com/watch?time_continue=646&v=HUMGc8hEkpc
That is because those videos are barely related to the Apparent FTL travel. They are both about "what happens if you travel faster than light through space, and why you cannot".
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I already did the math that demonstrates that this would very much be in ship 1's past. Do you have any specific disputes with that math?
I'll bite. Please provide math that supports this short story:
1. Ship uses A-FTL to (instantly) jump 100 light years away from point X, to point Y
2. At point Y, accelerates to 0.7c (instantly)
3. Ship uses A-FTL to jump (instantly) back from point Y to point X, ends up in its own past.
What part of "already did the math" did you not understand?
You claimed that you had read my posts with math from the beginning of the thread.
Here is a link to one that answers basically the same scenario, except with only 10 light years, and allowing 5 weeks travel time instead of instantaneous. Ship 2 in that scenario is exactly equivalent to a ship 1 that accelerates rapidly to match ship 2's speed. Instantaneous travel and larger distance only make the amount of time travel larger.
(Top of the quote is a link back to the full post)
Let me break it down with numbers. Define that Ship 1 is at rest in the Earth frame at t= 0, x = 0. At this time ship 1 activates its FTL drive, allowing it to arrive at a location in the earth frame of x = 10 light years, at time t = 5 weeks, (apparent speed of roughly 100 c). ...
Contrary to one of your previous posts where you claimed that I didn't account for length contraction, you can see in that post where I explicitly listed the length contracted distance to Earth.
PS. Yes I have read your examples, they are inadequate IMO. Just to point out some error, Observer1 at A sees distance from A to B to be 10ly, Observer2, traveling at relativistic speed of 0.7c passing A towards B would tell its a different distance; and to him, it would be. It is how relativity works. You ignored that completely in your calculations.
Like I said earlier, your math is not fully correct. For example, if ship1 and ship2 have same origin at x=0, and ship2 is going at 0.7c, then for ship2 to witness ship1's exit 10 light years away, would mean that in the tim reference of ship1, ship2 would have to have a head start of at least 14 years. So, ship2 leaves x=0 at year t=-14y, arrives at exit point at around t=5weeks. Then, jumps back, and he isnt getting back any of those 14 years, sorry. He still ends up at ship1's relative time of t=5weeks(+[5*timedilation]weeks if we assume its same A-FTL and not instant). So yeah, check all reference frames and you will see your math is wrong.
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...
This is a great primer for what the Lorentz Transformations are, and what the Speed of Light actually is.
yeah, I also posted these two other videos that specifically talk about superluminal travel... Kamill says he read the whole thread, but I think he skipped these videos
...
That is because those videos are barely related to the Apparent FTL travel. They are both about "what happens if you travel faster than light through space, and why you cannot".
Once again: It does not matter how you travel between two the two points, only that you can be at two places in space "faster than light can travel between them".
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I'll bite. Please provide math that supports this short story:
1. Ship uses A-FTL to (instantly) jump 100 light years away from point X, to point Y
2. At point Y, accelerates to 0.7c (instantly)
3. Ship uses A-FTL to jump (instantly) back from point Y to point X, ends up in its own past.
Okej, others have already demonstrated the math but I'll do your exercise. Lets assume that the A-FTL drive causes a flash of light when activated for visualization purposes. The numbers are slightly rounded by using a Lorentz factor of 1.4 instead of 1.4003 for 0.7 c.
Ship jumps from X to Y 100 light years away, sending out a light pulse that will reach Y in 100 years. If it were to jump back immediately the second light pulse would reach X in 100 years as well (and they would pass each other half way). The two events (departure and arrival) are simultaneous in this reference frame.
Instead the ship at Y instantly accelerates to 0.7 c towards X. The distance to X is now contracted to 100/1.4 = 71.4 light years and the light from X will arrive at Y in 100*1.4 = 140 years (as would be shown by the time dilation of a timer left at Y and now traveling at 0.7 c w.r.t. the ship). The light pulse will then have taken 71.4/(1-0.7) = 238 years to cover the distance and was therefore emitted from X 238-140 = 98 years ago in this reference frame. The ship jumps back to X and arrives 98 years after the pulse was sent and 71.4/(1+0.7) = 42 years before the light form its departure from Y arrives at X.
These times are 98/1.4 = 70 years and 42/1.4 = 30 years in the reference frame of X and Y. According to X the ships departs, arrives at Y and departs again instantaneously but returns 70 years in the future on the jump back. Inconvenient but maybe not a problem?
The symmetric scenario is that the ship instead accelerates instantaneously to 0.7 c away from X before making the second jump. The X-Y distance and the time of arrival of the departure light pulse at Y are again 71.4 light years and 140 years in the future. The pulse will now have taken 71.4/(1+0.7) = 42.0 years to cover the distance and must therefore be emitted 140-42= 98 years in the future in this reference frame. The ship jumps back to X and arrives 98 years before the pulse was sent and 71.4/(1-0.7) = 238 years before the light from its departure from Y arrives at X.
These times are 98/1.4 = 70 years and 238/1.4 = 170 years in the reference frame of X and Y. According to X the ships departs, arrives at Y and departs again instantaneously but returns 70 years before it left on the jump back...
Please let me know if I made any errors.
EDIT: Fixed some grammar.
EDIT: Of course I get the directions wrong :P Never mind ::)
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Like I said earlier, your math is not fully correct.
You said earlier that I didn't account for length contractino, when i explicitly did.
For example, if ship1 and ship2 have same origin at x=0, and ship2 is going at 0.7c, then for ship2 to witness ship1's exit 10 light years away, would mean that in the tim reference of ship1, ship2 would have to have a head start of at least 14 years.
First, it is irrelevant whether ship 2 started from Earth, or took some other path to end up there and as I stated, the result is the same as if ship 1 rapidly accelerates to 0.7 c after the jump. The "same origin" is simply part of applying the Lorentz transformation. The math is just simpler if you define the origins to be the same event.
Second, time dilation means that it has not been 14 years for ship 2, if ship 2 had originally departed from Earth.
So, ship2 leaves x=0 at year t=-14y, arrives at exit point at around t=5weeks.
Those numbers are all in the ship 1 frame, but time and distance for ship 2 need to be measured in the ship 2 frame.
Then, jumps back, and he isnt getting back any of those 14 years, sorry.
Not 14 years, if you actually calculate it, you would find the time of Ship1 exiting FTL is t=-483 weeksin its own frame.
He still ends up at ship1's relative time of t=5weeks(+[5*timedilation]weeks if we assume its same A-FTL and not instant). So yeah, check all reference frames and you will see your math is wrong.
This is simply untrue because you did not apply the Lorentz transformation, and you are trying to calculate ship 2's behavior in something other than its own rest frame. Since all frames are equal, the ship 2 rest frame is equally valid, and we defined the FTL speed as relative to the ship's own rest frame.
You are the one who needs to learn to do calculations in different frames.
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Instead the ship at Y instantly accelerates to 0.7 c towards X.
This is the wrong direction of acceleration if you want to setup time travel to the past.
Your calculations attempt to simply use the time dilation and length contraction effects. these are not the full story of relativity, you instead need to use the full Lorentz transformations that have the time dilation and length contraction embedded in them, but also account for movement of the origins of the frames.
The distance to X is now contracted to 100/1.4 = 71.4 light years and the light from X will arrive at Y in 100*1.4 = 140 years (as would be shown by the time dilation of a timer left at Y and now traveling at 0.7 c w.r.t. the ship). The light pulse will then have taken 71.4/(1-0.7) = 238 years to cover the distance and was therefore emitted from X 238-140 = 98 years ago in this reference frame.
No, speed of light is the same in every frame, and in this frame the earth is travelling towards the source of the signal, so they will meet in the middle in just 71.4/(1+0.7) = 42 years. Also, since the acceleration happens at the same time and location as the light pulse, the light pulse in this frame was just emitted.
The ship jumps back to X and arrives 98 years after the pulse was sent and 71.4/(1+0.7) = 42 years before the light form its departure from Y arrives at X.
These times are 98/1.4 = 70 years and 42/1.4 = 30 years in the reference frame of X and Y.
Somehow some of your backwards description canceled out, so you got to the arriving 42 years before the light (in the Y frame) answer correctly. Also, you are correct that it arrives at t = 70 years in the X frame, but the calculation of t' = 30 years in the Y frame does not make sense. I think part of the problem is that you never clearly defined the origin of the Y frame. Usually you pick the origin of the 2 frames to be the same event in spacetime (the ship originally departing point X in this case.) With that definition, the time in that frame is the 98 years number. By the construction of the problem, this is the same time in the Y frame as the time in the Y frame at point Y just before the jump. Your calculation of 42/1.4 = 30 is actually the calculation of how many years remaining before the light pulse arrives at X in the X frame as of when the ship arrives back at X.
According to X the ships departs, arrives at Y and depart again instantaneously but returns 70 years in the future on the jump back. Inconvenient but maybe not a problem?
This is correct, it is the other direction of acceleration that leads to a paradox.
Please let me know if I made any errors.
Let me know if you are still confused, and I can try to help. I don't think I did a particularly good job explaining in this post, so I assume you will have questions.
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Instead the ship at Y instantly accelerates to 0.7 c towards X.
This is the wrong direction of acceleration if you want to setup time travel to the past.
Your calculations attempt to simply use the time dilation and length contraction effects. these are not the full story of relativity, you instead need to use the full Lorentz transformations that have the time dilation and length contraction embedded in them, but also account for movement of the origins of the frames.
You had me confused with the directions there for a while - are you saying I'm correct (boost away to put your FTL origin in the future and back to put it in the past)? I did both to show the difference.
I was trying to visualize it a bit more than just boosting coordinates as that has been done in the thread already. As you say, you can do it manually by time dilation and length contraction if you consider the shifting of the origin.
The distance to X is now contracted to 100/1.4 = 71.4 light years and the light from X will arrive at Y in 100*1.4 = 140 years (as would be shown by the time dilation of a timer left at Y and now traveling at 0.7 c w.r.t. the ship). The light pulse will then have taken 71.4/(1-0.7) = 238 years to cover the distance and was therefore emitted from X 238-140 = 98 years ago in this reference frame.
No, speed of light is the same in every frame, and in this frame the earth is travelling towards the source of the signal, so they will meet in the middle in just 71.4/(1+0.7) = 42 years. Also, since the acceleration happens at the same time and location as the light pulse, the light pulse in this frame was just emitted.
Yes, the speed of light is 1, I'm just being lazy and calculating the time as how far ahead of X the first light pulse has to get divided by the relative speed.
The ship jumps back to X and arrives 98 years after the pulse was sent and 71.4/(1+0.7) = 42 years before the light form its departure from Y arrives at X.
These times are 98/1.4 = 70 years and 42/1.4 = 30 years in the reference frame of X and Y.
Somehow some of your backwards description canceled out, so you got to the arriving 42 years before the light (in the Y frame) answer correctly. Also, you are correct that it arrives at t = 70 years in the X frame, but the calculation of t' = 30 years in the Y frame does not make sense. I think part of the problem is that you never clearly defined the origin of the Y frame. Usually you pick the origin of the 2 frames to be the same event in spacetime (the ship originally departing point X in this case.) With that definition, the time in that frame is the 98 years number. By the construction of the problem, this is the same time in the Y frame as the time in the Y frame at point Y just before the jump. Your calculation of 42/1.4 = 30 is actually the calculation of how many years remaining before the light pulse arrives at X in the X frame as of when the ship arrives back at X.
This is a little confusing - X and Y are two points in space the same reference frame, with the second frame being that of the boosted ship. Yes, I mix and match a bit between the frames here, I guess it doesn't help the clarity...
According to X the ships departs, arrives at Y and depart again instantaneously but returns 70 years in the future on the jump back. Inconvenient but maybe not a problem?
This is correct, it is the other direction of acceleration that leads to a paradox.
Please let me know if I made any errors.
Let me know if you are still confused, and I can try to help. I don't think I did a particularly good job explaining in this post, so I assume you will have questions.
I'm unsure of whether I'm confused or not :) If I put the origin at Y=(x,t)=(0 light years, 0 years) I get:
Go from Earth at X=(-100,0) to Y=(0,0), boost to v=+0.7 c (i.e. away from X)
=> You're now at Y'=(0,0) and you left in the future at X'=(-140,98).
Earth is currently at (-71.4,0), go there and boost back
=> You're now at (-100,-70), i.e. same location you started from (Earth) but 70 years before you left.
EDIT: Clarified by starting from Earth.
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Instead the ship at Y instantly accelerates to 0.7 c towards X.
This is the wrong direction of acceleration if you want to setup time travel to the past.
Your calculations attempt to simply use the time dilation and length contraction effects. these are not the full story of relativity, you instead need to use the full Lorentz transformations that have the time dilation and length contraction embedded in them, but also account for movement of the origins of the frames.
You had me confused with the directions there for a while - are you saying I'm correct (boost away to put your FTL origin in the future and back to put it in the past)? I did both to show the difference.
I only went through the math on the accelerate towards point X version, which you correctly concluded does not lead to a paradox.
I'm unsure of whether I'm confused or not :) If I put the origin at Y=(x,t)=(0 light years, 0 years) I get:
Go from X=(-100,0) to Y=(0,0), boost to v=+0.7 c (i.e. away from X)
=> You're now at Y'=(0,0) and you left in the future at X'=(-140,98).
Location X' is currently at (-71.4,0), go there and boost back
=> You're now at (-100,-70), i.e. same location you started from but 70 years before you left.
Yes, I believe that is all correct. The main errors I saw in your original post were in your description of the time light takes (I can't see a relevant frame where light would be travelling for 238 years, because none of the distances are that large. Looking again, this seems to be due to you flipping the sign on the velocity, treating it as if X was moving away from Y in the setup where X was moving towards Y.)
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The underlying question is:
Does the Lorentz Transformation (And Fitzgerald Contraction) actually apply at supraluminal speeds (if such a thing exits)?
I am not voicing an opinion about this, just noting that is what the debate is about.
I will note - if it does, the object would have a negative length, to go along with travelling backwards in time.
Also, what would be perceived inside such a reference frame? How would it be perceived from an external reference frame?
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https://www.youtube.com/watch?v=msVuCEs8Ydo
This is a great primer for what the Lorentz Transformations are, and what the Speed of Light actually is.
yeah, I also posted these two other videos that specifically talk about superluminal travel... Kamill says he read the whole thread, but I think he skipped these videos
https://www.youtube.com/watch?v=1YFrISfN7jo
https://www.youtube.com/watch?time_continue=646&v=HUMGc8hEkpc
That is because those videos are barely related to the Apparent FTL travel. They are both about "what happens if you travel faster than light through space, and why you cannot".
no, there is a third video, which you can only see the link, which uses the example of a WARP DRIVE ship. Link corrected so you can see the video
https://www.youtube.com/watch?v=HUMGc8hEkpc
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maybe Miguel Alcubierre, the guy who invented the concept of warp drive (as we think it nowadays), can convince you?
https://www.youtube.com/watch?v=zj5Jxux4uYk
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maybe Miguel Alcubierre, the guy who invented the concept of warp drive (as we think it nowadays), can convince you?
He gives the basic problem near the beginning (the light cone diagrams we have all seen, the problem of simultaneous being different for different observers.)
https://www.youtube.com/watch?v=zj5Jxux4uYk?t=626 (or go to 10:26)
Starts talking about Grandfather paradox here: https://www.youtube.com/watch?v=zj5Jxux4uYk?t=2700 (45:00 minutes)
Doesn't really talk about how to get around it except to say the causality conjecture does not specifically ban FTL, it would just step in and mess up any attempt to create a time machine, perhaps sort of like feedback of a microphone (I think he said something like that in there somewhere). Doesn't really explain what rules it would impose in practice.
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Im keeping out of all the special relativity tutorials :)
Anyone got an opinion in whether there are conservation issues even if the grandfather paradoxes are avoided?
I brought up a specific case where from one observer's perspective an FTL flight would lead to an overlap, where for a period the FTL vehicle would exist as two instances simultaneously, and the universe would have a bit more mass. Another observer travelling with the opposite velocity observing the same FTL flight would experience a period where the FTL vehicle's mass had vanished from the universe.
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Im keeping out of all the special relativity tutorials :)
Anyone got an opinion in whether there are conservation issues even if the grandfather paradoxes are avoided?
I brought up a specific case where from one observer's perspective an FTL flight would lead to an overlap, where for a period the FTL vehicle would exist as two instances simultaneously, and the universe would have a bit more mass. Another observer travelling with the opposite velocity observing the same FTL flight would experience a period where the FTL vehicle's mass had vanished from the universe.
Local conservation might be violated depending on the details, but I think globally it is potentially okay (with the caveat that general relativity already produces problems with even defining global conservation laws). Spacelike separated events can't effect each other (and to the extent they can because we are assuming FTL, we are barring certain offensive situations) so I don't see this as being a problem. I could be missing something though.Seeing something in 2 places wouldn't be a problem, I believe that already happens with some gravitational lensing. Bringing the 2 versions of an object too close together to exploit there being 2 of them in a certain frame would run afoul of the no causality violation conditions.
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Like I said earlier, your math is not fully correct.
You said earlier that I didn't account for length contractino, when i explicitly did.
For example, if ship1 and ship2 have same origin at x=0, and ship2 is going at 0.7c, then for ship2 to witness ship1's exit 10 light years away, would mean that in the tim reference of ship1, ship2 would have to have a head start of at least 14 years.
First, it is irrelevant whether ship 2 started from Earth, or took some other path to end up there and as I stated, the result is the same as if ship 1 rapidly accelerates to 0.7 c after the jump. The "same origin" is simply part of applying the Lorentz transformation. The math is just simpler if you define the origins to be the same event.
Second, time dilation means that it has not been 14 years for ship 2, if ship 2 had originally departed from Earth.
So, ship2 leaves x=0 at year t=-14y, arrives at exit point at around t=5weeks.
Those numbers are all in the ship 1 frame, but time and distance for ship 2 need to be measured in the ship 2 frame.
Then, jumps back, and he isnt getting back any of those 14 years, sorry.
Not 14 years, if you actually calculate it, you would find the time of Ship1 exiting FTL is t=-483 weeksin its own frame.
He still ends up at ship1's relative time of t=5weeks(+[5*timedilation]weeks if we assume its same A-FTL and not instant). So yeah, check all reference frames and you will see your math is wrong.
This is simply untrue because you did not apply the Lorentz transformation, and you are trying to calculate ship 2's behavior in something other than its own rest frame. Since all frames are equal, the ship 2 rest frame is equally valid, and we defined the FTL speed as relative to the ship's own rest frame.
You are the one who needs to learn to do calculations in different frames.
I did say "t" isntead of "t' " on purpose, cause if your calculation does not hold up in Ship1's reference, there must be something wrong with it. In Ship1's time reference, Ship2 must have left "x=0" 14 years earlier. Jumping back wont give that time back to Ship2.
Later in this thread RSE fairly noted that Lorentz transformations might not apply for A-FTL. I agree with that, as C is clearly broken, but not in a way that would result in time travels.
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no, there is a third video, which you can only see the link, which uses the example of a WARP DRIVE ship. Link corrected so you can see the video
https://www.youtube.com/watch?v=HUMGc8hEkpc
The video proves nothing but the fact that the math used today to do those calculations is not valid from all reference frames, hence it must be somehow broken. Lets recap, in the end of the video, Matthew transforms the field to a perspective of 0.99c traveler, fine. In that field, he draws a world paths for the Paradox ship that go beyond the causality plane and then back, showing how it could end up on X=0, about 100 years before its departure. This proves just how exactly Lorentz transformation is not applicable in this case, as such travel can only be possible in the eyes of the 0.99c Ship, but not the Paradox ship it self, that still has a clock that ticks forward, as same rate as on Earth (X=0). The issue comes from the fact that in Lorentz transformation, time axis is reversed if speed > c, while this is only the case for speed through space, not with space. That's why in the causality plane going beyond the field and then back can look like rewinding some time, while its not. The diagram supposed to be for an A-FTL travel, while it clearly assumes the time on board the Paradox ship reverses as it goes beyond the causality plane, and it does not (again, it remains in sync with Earth time/tick/ratio).
Let's take a look are Paradox ship reference frame again, it moves along Earth time axis, and no matter where it would go, its clock (same as Earths) would move forward, in sync, hence no matter the destination & way/path back, it would never end up in its past (without actually breaking C speed through space).
Having said that, let's do a small thought experiment. Let's assume, we, here on Earth, have this magical universe remote control device with 2 buttons, button1 freezes entire Universe, however big it is, and for every coordindate within it, assigns a clock, resets it to zero. We have pressed it. Now, button2 gives us access to any clock value from any coordinate in space, relative to the moment we have pressed it here on Earth. With incorrect math, clocks beyond our visible/causally connected Universe would be negative, as they move away at speed > c, (like A-FTL). Good math/transformation should give a positive value, no matter how small for any point in the entire Universe, not matter how small, but it would be > 0.
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I did say "t" isntead of "t' " on purpose, cause if your calculation does not hold up in Ship1's reference, there must be something wrong with it. In Ship1's time reference, Ship2 must have left "x=0" 14 years earlier. Jumping back wont give that time back to Ship2.
Yes, something is wrong when you get causality violations, but the thing that is wrong is FTL. You can't actually point out a calculation I have done wrong because I did everything correct. The problem is assuming FTL. Meanwhile, you aren't even responding to the objection I already made showing that your statement is fundamentally contradictory to relativitySecond, time dilation means that it has not been 14 years for ship 2, if ship 2 had originally departed from Earth.
Later in this thread RSE fairly noted that Lorentz transformations might not apply for A-FTL. I agree with that, as C is clearly broken, but not in a way that would result in time travels.
Lorentz transformations do apply. They apply to the objects moving in different reference frames, and no reference frame is different than another. RSE was talking about the objects during the jump, but this doesn't matter, all that matters is their coordinates and relative speeds at the beginning and end of the jumps.
The video proves nothing but the fact that the math used today to do those calculations is not valid from all reference frames, hence it must be somehow broken.
No, again, you have not shown that the math is inapplicable, you just refuse to even consider that the premise of "FTL exists" can be an incorrect assumption. Relativity is the only theory that consistently explains how physics works in all reference frames, so unless you have an alternative that can also explain all of the experiments confirming relativity, we are stuck with it. Also, you apparently skipped over the video where the person who came up with the modern concept of how to build a warp drive explains that even if it was possible to build such a device, it would violate causality.
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I did say "t" isntead of "t' " on purpose, cause if your calculation does not hold up in Ship1's reference, there must be something wrong with it. In Ship1's time reference, Ship2 must have left "x=0" 14 years earlier. Jumping back wont give that time back to Ship2.
Yes, something is wrong when you get causality violations, but the thing that is wrong is FTL. You can't actually point out a calculation I have done wrong because I did everything correct. The problem is assuming FTL. Meanwhile, you aren't even responding to the objection I already made showing that your statement is fundamentally contradictory to relativitySecond, time dilation means that it has not been 14 years for ship 2, if ship 2 had originally departed from Earth.
Later in this thread RSE fairly noted that Lorentz transformations might not apply for A-FTL. I agree with that, as C is clearly broken, but not in a way that would result in time travels.
Lorentz transformations do apply. They apply to the objects moving in different reference frames, and no reference frame is different than another. RSE was talking about the objects during the jump, but this doesn't matter, all that matters is their coordinates and relative speeds at the beginning and end of the jumps.
The video proves nothing but the fact that the math used today to do those calculations is not valid from all reference frames, hence it must be somehow broken.
No, again, you have not shown that the math is inapplicable, you just refuse to even consider that the premise of "FTL exists" can be an incorrect assumption. Relativity is the only theory that consistently explains how physics works in all reference frames, so unless you have an alternative that can also explain all of the experiments confirming relativity, we are stuck with it. Also, you apparently skipped over the video where the person who came up with the modern concept of how to build a warp drive explains that even if it was possible to build such a device, it would violate causality.
You cannot apply Lorentz transformation for an object that jumped over space, instead of traveling through it. It will end up in a mess that makes it look like there are paradoxes possible. If you watch the video again, you will see that Matthew first shows how everything looks good from Paradox ship reference, but wrong from 0.99c-ship reference, therefore, Paradox ship ends up in the past? No, what about the first chart, it was all good in Paradox ship reference, he simply doesn't address that anymore. How convenient.
I did not skip the video, I do not agree with the statements within it. Big claim? I do not think so. We can all agree that everything should follow cause and effect from all reference frames, despite how it might look like from there (B before A, etc.), then why do you insist the FTL is the problem, if the supposed "proof" why it'S the problem, is not even consistent from within two reference frames? You cannot disprove something with a broken solution (again, when you transform any distance via Lorentz, it automatically assumes that distance was traveled through space, and in A-FTL case it is simply not true).
PS. To do a proper Lorentz transformation for an A-FTL drive, the distance delta has to be set to 0. So technically, the ship as far the transformation is concerned has never even moved. Then feel free to recalculate.
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You cannot apply Lorentz transformation for an object that jumped over space, instead of traveling through it. It will end up in a mess that makes it look like there are paradoxes possible. If you watch the video again, you will see that Matthew first shows how everything looks good from Paradox ship reference, but wrong from 0.99c-ship reference, therefore, Paradox ship ends up in the past? No, what about the first chart, it was all good in Paradox ship reference, he simply doesn't address that anymore. How convenient.
You are the one trying to conveniently ignore a reference frame. By only picking one reference frame, you are defining a frame for absolute simultaneity. We know that there is no such thing as absolute simultaneity, and for something to be possible, it has to be consistent in any reference frame. The Lorentz transformations are only being applied to the objects just before/after the FTL jumps, so it does not matter what happens during the jump.
I did not skip the video, I do not agree with the statements within it. Big claim? I do not think so.
You are disagreeing with someone recognized as one of the world's experts on general relativity, and the entire basis of your objection is that his statements don't allow FTL. Do you see the inherent arrogance in your statement?
We can all agree that everything should follow cause and effect from all reference frames, despite how it might look like from there (B before A, etc.), then why do you insist the FTL is the problem, if the supposed "proof" why it'S the problem, is not even consistent from within two reference frames?
The inconsistency is the proof. It is called proof by contradiction. FTL has never been demonstrated, however, special relativity has countless supporting experiments. You cannot have both while also maintaining causality.
You cannot disprove something with a broken solution (again, when you transform any distance via Lorentz, it automatically assumes that distance was traveled through space, and in A-FTL case it is simply not true).
PS. To do a proper Lorentz transformation for an A-FTL drive, the distance delta has to be set to 0. So technically, the ship as far the transformation is concerned has never even moved. Then feel free to recalculate.
What "distance delta"? That is simply not a defined term. There are spacetime coordinates of different events in different reference frames, and the Lorentz transformations describe how to translate between them. The relevant events are all taken just before or after the FTL jump, and there is no relevance to how an object moved between the events.
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You are the one trying to conveniently ignore a reference frame. By only picking one reference frame, you are defining a frame for absolute simultaneity. We know that there is no such thing as absolute simultaneity, and for something to be possible, it has to be consistent in any reference frame. The Lorentz transformations are only being applied to the objects just before/after the FTL jumps, so it does not matter what happens during the jump.
I'm not picking a frame. I'm merely stating that if you want to prove something wrong, your solution must be self-consistent too, right? So to prove A-FTL results in a time travel, time-travel must be observable from all reference frames, not just one. If it's noticeable only from one, then there is a problem of your proof, thus making it invalid.
(...)
You are disagreeing with someone recognized as one of the world's experts on general relativity, and the entire basis of your objection is that his statements don't allow FTL. Do you see the inherent arrogance in your statement?
So, these days if you want to disagree with someone with a title, you are automatically ignorant? Do you really think it works that way? Sorry to hear that.
(...)
The inconsistency is the proof. It is called proof by contradiction. FTL has never been demonstrated, however, special relativity has countless supporting experiments. You cannot have both while also maintaining causality.
That's exactly the case here. Special relativity has countless supporting experiments, and they are all based on data where particles travel at <=c through space. Even Lorentz transformations have this embedded so they are not fully adequate for theoretical A-FTL calculations.
(...)
What "distance delta"? That is simply not a defined term. There are spacetime coordinates of different events in different reference frames, and the Lorentz transformations describe how to translate between them. The relevant events are all taken just before or after the FTL jump, and there is no relevance to how an object moved between the events.
That's not true. If we take points A and B separated by some distance and use regular 0.7c-capable drive to get there in 10 days, and then A-FTL drive but crank down the engine to go at 0.7c as well, they both end up at B at the same time, but their reference frames are not same. While in your different perspective transformations they would be treated as such. That is why if we add A-FTL the the mix you end up with negative-value transformations that are wrong.
The only case that results in a time-travel that I can see could be illustrated using a traversable worm hole, where both ends are at coordinates that are at different relative velocities. Say A is at rest B is moving towards (or away from) A at 0.XXc. You cross the tunnel at T=0 from A to B, spend 10 years at B, go back to A at T'=10years and you can either end up at time T=10+(0..N) years or T=10-(10-(10/N)) years (yeah, this can never go negative, but can come infinitely close to zero. At best, you can almost instantly leave A and arrive back, or leave A and come back billion years later. Never in the past though.
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gee... another video, from the Starship Conference... you mostly have guys working with FTL here... including the first talk, by Dr Sonny White (the guy from the Warp Drive NASA "ship"), etc
Skip to 59 minutes. Talk by Eric Davies.
He shows how the LOCAL LIGHT cone can rotate, so that LOCALLY, in a WARP DRIVE OR WORMHOLE (he specifically mentions both too), FTL and Causality are not violated.
But even if the LOCAL causality is not violated, he clearly shows that for an outside observer, the ship WILL BE TRAVELLING BACK IN TIME.
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(...)
You are the one trying to conveniently ignore a reference frame. By only picking one reference frame, you are defining a frame for absolute simultaneity. We know that there is no such thing as absolute simultaneity, and for something to be possible, it has to be consistent in any reference frame. The Lorentz transformations are only being applied to the objects just before/after the FTL jumps, so it does not matter what happens during the jump.
I'm not picking a frame. I'm merely stating that if you want to prove something wrong, your solution must be self-consistent too, right? So to prove A-FTL results in a time travel, time-travel must be observable from all reference frames, not just one. If it's noticeable only from one, then there is a problem of your proof, thus making it invalid.
All reference frames agree on the causality violation which you would see if you ever actually did the math. They disagree on which leg of the trip time travel happens during, but they agree on the net result. When you refuse to consider the second FTL jump from its own rest frame.
(...)
You are disagreeing with someone recognized as one of the world's experts on general relativity, and the entire basis of your objection is that his statements don't allow FTL. Do you see the inherent arrogance in your statement?
So, these days if you want to disagree with someone with a title, you are automatically ignorant? Do you really think it works that way? Sorry to hear that.
When you don't have a single technical argument against them, and they have spent their life studying the topic? Note that I used the word arrogance, you brought up ignorant.
(...)
The inconsistency is the proof. It is called proof by contradiction. FTL has never been demonstrated, however, special relativity has countless supporting experiments. You cannot have both while also maintaining causality.
That's exactly the case here. Special relativity has countless supporting experiments, and they are all based on data where particles travel at <=c through space. Even Lorentz transformations have this embedded so they are not fully adequate for theoretical A-FTL calculations.
I said this repeatedly, but you seem to have missed it: all calculations are done before/after the jumps so that the nature of the jumps doesn't matter. What does matter is that since all reference frames are equivalent, you should use the rest frame of the ship just before the jump for consistency.
(...)
What "distance delta"? That is simply not a defined term. There are spacetime coordinates of different events in different reference frames, and the Lorentz transformations describe how to translate between them. The relevant events are all taken just before or after the FTL jump, and there is no relevance to how an object moved between the events.
That's not true. If we take points A and B separated by some distance and use regular 0.7c-capable drive to get there in 10 days, and then A-FTL drive but crank down the engine to go at 0.7c as well, they both end up at B at the same time, but their reference frames are not same. While in your different perspective transformations they would be treated as such. That is why if we add A-FTL the the mix you end up with negative-value transformations that are wrong.
If you turn off the warp drive, and then the ship is stationary, this means it obviously has a different reference frame than the other ship if the other ship is still moving. If you then accelerate it to 0.7 c or stop the other ship then they have the same reference frame. I seriously don't have a clue how you think this changes or counters anything about what I said.
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gee... another video, from the Starship Conference... you mostly have guys working with FTL here... including the first talk, by Dr Sonny White (the guy from the Warp Drive NASA "ship"), etc
Skip to 59 minutes. Talk by Eric Davies.
He shows how the LOCAL LIGHT cone can rotate, so that LOCALLY, in a WARP DRIVE OR WORMHOLE (he specifically mentions both too), FTL and Causality are not violated.
But even if the LOCAL causality is not violated, he clearly shows that for an outside observer, the ship WILL BE TRAVELLING BACK IN TIME.
Can't find that video, but it sounds like he meant that the Observer could only draw such conclusion, that some event happened way before it could have, ergo time travel, but in reality this would be just a distorted view. If such observer then navigated to a location and asked the inhabitants around, he would learn that all events happened in proper, causally correct order.
That being said, there are few other examples that could fool the Observer, for instance, an A-FTL ship (with instant jumps), could calculate a set of points in a spherical configuration around the Observer and jump to each one at slightly decreased distance, each time generating a flash of lower intensity & wavelength. Observer would then see the same flash appear all at once everywhere around him. To scientist on board it would be hard to figure the event order. Point being, doesn't matter what the Observer can see, reality might be completely different.
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here the video, forgot the link
https://www.youtube.com/watch?v=ucyBMB_PWr8
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I've been looking for an experiment where SR is tested for symmetry. Have there been any tests, where the "observer" has been accelerated to relativistic speeds, and the clock in the laboratory frame was observed to be time-dilated?
Time dilation in GR is due to the equivalence principle. It is not symmetrical. Someone in a gravity well, will look up and see time moving faster in the rest of the universe, not slower. In general, if anything is "accelerated" to a relativistic velocity delta, "v - v0", it is equivalent to a gravitational field and changing the (Newtonian) gravitational potential. In which case, when it stops accelerating it is at a lower gravitational potential than where it started from.
Nobody would use Lorentz transformations to compare two inertial reference frames that have "different" gravitational potentials. But, that is precisely what we are doing when we assume SR is symmetrical and there is no experiment that can be done to tell which one is moving. I can't find any "relativistic" experiment that actually verifies this assumption. Lorentz transformations are based on it. It is "Math" but has such symmetry been verified physically?
Any assistance or references would be appreciated.
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I've been looking for an experiment where SR is tested for symmetry. Have there been any tests, where the "observer" has been accelerated to relativistic speeds, and the clock in the laboratory frame was observed to be time-dilated?
The Hafele-Keating experiment is probably the closest thing to what you're looking for. Not quite the same, as the laboratory frame is defined as that of the center of the Earth at rest; and the Earth-surface frame is actually a third 'observer' frame. That said, the three 'observer' frames all behaved as expected within error limits. More importantly, IMO, is that the duration of the test allowed it to both detect and divorce both types of relativistic effects even though the velocities involved aren't traditionally considered relativistic. In principal, it should be very straightforward to do a twin-paradox-esque experiment with today's technology; though I know of no plans to do so.
If we relax our definition of 'clock', then we can consider other experiements such as muon lifetime experiements (e.g., Frisch-Smith), where the half-lives of unstable particles increase drastically at relativistic velocities. Running variations of this experiment is quite popular with students today. Perhaps this is more to your liking, as the very existence of the particle itself confirms that the effect is more than a mere mathematical curiosity.
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I've been looking for an experiment where SR is tested for symmetry. Have there been any tests, where the "observer" has been accelerated to relativistic speeds, and the clock in the laboratory frame was observed to be time-dilated?
The Hafele-Keating experiment is probably the closest thing to what you're looking for. Not quite the same, as the laboratory frame is defined as that of the center of the Earth at rest; and the Earth-surface frame is actually a third 'observer' frame. That said, the three 'observer' frames all behaved as expected within error limits. More importantly, IMO, is that the duration of the test allowed it to both detect and divorce both types of relativistic effects even though the velocities involved aren't traditionally considered relativistic. In principal, it should be very straightforward to do a twin-paradox-esque experiment with today's technology; though I know of no plans to do so.
If we relax our definition of 'clock', then we can consider other experiements such as muon lifetime experiements (e.g., Frisch-Smith), where the half-lives of unstable particles increase drastically at relativistic velocities. Running variations of this experiment is quite popular with students today. Perhaps this is more to your liking, as the very existence of the particle itself confirms that the effect is more than a mere mathematical curiosity.
Thanks, but it's not quite what I was looking for. The clocks were compared to determine the elapsed time when they were brought back down to the lab. They apparently were not compared when actually in flight.
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I've been looking for an experiment where SR is tested for symmetry. Have there been any tests, where the "observer" has been accelerated to relativistic speeds, and the clock in the laboratory frame was observed to be time-dilated?
The Hafele-Keating experiment is probably the closest thing to what you're looking for. Not quite the same, as the laboratory frame is defined as that of the center of the Earth at rest; and the Earth-surface frame is actually a third 'observer' frame. That said, the three 'observer' frames all behaved as expected within error limits. More importantly, IMO, is that the duration of the test allowed it to both detect and divorce both types of relativistic effects even though the velocities involved aren't traditionally considered relativistic. In principal, it should be very straightforward to do a twin-paradox-esque experiment with today's technology; though I know of no plans to do so.
If we relax our definition of 'clock', then we can consider other experiements such as muon lifetime experiements (e.g., Frisch-Smith), where the half-lives of unstable particles increase drastically at relativistic velocities. Running variations of this experiment is quite popular with students today. Perhaps this is more to your liking, as the very existence of the particle itself confirms that the effect is more than a mere mathematical curiosity.
Thanks, but it's not quite what I was looking for. The clocks were compared to determine the elapsed time when they were brought back down to the lab. They apparently were not compared when actually in flight.
Tests of time dilation using particle lifetimes are comparisons while in flight. The most basic test of the symmetry described by special relativity is the Michelson Morley experiment. Can you describe a theory that can accurately predict the results of the above experiments and Michelson Morley, yet diverges for some other test of symmetry?
Otherwise you are just asking for a wild goose chase, since these experiments solidly confirm the symmetry of special relativity.
In which case, when it stops accelerating it is at a lower gravitational potential than where it started from.
An object can be accelerated from the ground to Earth orbit, or from Earth orbit to the ground. How exactly can you say that the end result of an acceleration results in a lower gravitational potential in general?
To put things another way: the acceleration only is producing the same time dilation as being stationary in a gravitational field while the acceleration is happening. This different time dilation is what makes the difference between the twins in the "twin paradox" which can be solved using Lorentz transformations. Your description of an accelerated object ending up in a lower gravitational potential does not make sense here.
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Tests of time dilation using particle lifetimes are comparisons while in flight. The most basic test of the symmetry described by special relativity is the Michelson Morley experiment. Can you describe a theory that can accurately predict the results of the above experiments and Michelson Morley, yet diverges for some other test of symmetry?
Otherwise you are just asking for a wild goose chase, since these experiments solidly confirm the symmetry of special relativity.
In which case, when it stops accelerating it is at a lower gravitational potential than where it started from.
An object can be accelerated from the ground to Earth orbit, or from Earth orbit to the ground. How exactly can you say that the end result of an acceleration results in a lower gravitational potential in general?
To put things another way: the acceleration only is producing the same time dilation as being stationary in a gravitational field while the acceleration is happening. This different time dilation is what makes the difference between the twins in the "twin paradox" which can be solved using Lorentz transformations. Your description of an accelerated object ending up in a lower gravitational potential does not make sense here.
The issue is about "Reciprocity" not symmetry.
This page, https://en.wikipedia.org/wiki/Time_dilation (https://en.wikipedia.org/wiki/Time_dilation) has a well written section on Reciprocity in SR, "velocity time dilation". Then in the next section on Gravitational time dilation it says;
"Contrarily to velocity time dilation, in which both observers measure the other as aging slower (a reciprocal effect), gravitational time dilation is not reciprocal. This means that with gravitational time dilation both observers agree that the clock nearer the center of the gravitational field is slower in rate, and they agree on the ratio of the difference."
The Hafele and Keating experiment supports no-reciprocity. Even the Michelson-Moorley experiment does not demonstrate reciprocity. So far, I have not found any experimental evidence to support a reciprocity effect. Gravitational time dilation is the result of the Equivalence principle alone, not any particular solution of GR.
Reciprocity is a requirement of the Lorentz transformation and the Lorentz group, it is assumed in its derivation. Reciprocity is what forces the paradox to happen. Reciprocity is not one of the postulates of SR. It is an assumption that reciprocity is required for "The laws of physics to remain invariant in all inertial reference frames". However, it is trivial to show that the law of physics remain unchanged, even when the flat Minkowski metric is transformed by a constant coefficient "A", in such a way that;
ds2 = (1/A)*c2dt2 - A*(dx2 + dy2 + dz2)
Resulting in a scaled system of units where "force" is an invariant wrt the constant "A". Leaving all physical laws and experimental data, including EM fields unchanged, but the transformation from A=1 to A>1 is not reciprocal. In the latter time is slow, in the former it's not. No reciprocity, no paradox. IMO this too is the result of the Equivalence principle, when one body accelerates to velocity v=0.6c and the other does not. The end result is not reciprocal.
As far as I'm concerned, until someone shows evidence of reciprocity, it is by no means proven.
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Tests of time dilation using particle lifetimes are comparisons while in flight. The most basic test of the symmetry described by special relativity is the Michelson Morley experiment. Can you describe a theory that can accurately predict the results of the above experiments and Michelson Morley, yet diverges for some other test of symmetry?
Otherwise you are just asking for a wild goose chase, since these experiments solidly confirm the symmetry of special relativity.
In which case, when it stops accelerating it is at a lower gravitational potential than where it started from.
An object can be accelerated from the ground to Earth orbit, or from Earth orbit to the ground. How exactly can you say that the end result of an acceleration results in a lower gravitational potential in general?
To put things another way: the acceleration only is producing the same time dilation as being stationary in a gravitational field while the acceleration is happening. This different time dilation is what makes the difference between the twins in the "twin paradox" which can be solved using Lorentz transformations. Your description of an accelerated object ending up in a lower gravitational potential does not make sense here.
The issue is about "Reciprocity" not symmetry.
This page, https://en.wikipedia.org/wiki/Time_dilation (https://en.wikipedia.org/wiki/Time_dilation) has a well written section on Reciprocity in SR, "velocity time dilation". Then in the next section on Gravitational time dilation it says;
"Contrarily to velocity time dilation, in which both observers measure the other as aging slower (a reciprocal effect), gravitational time dilation is not reciprocal. This means that with gravitational time dilation both observers agree that the clock nearer the center of the gravitational field is slower in rate, and they agree on the ratio of the difference."
The Hafele and Keating experiment supports no-reciprocity. Even the Michelson-Moorley experiment does not demonstrate reciprocity. So far, I have not found any experimental evidence to support a reciprocity effect. Gravitational time dilation is the result of the Equivalence principle alone, not any particular solution of GR.
Reciprocity is a requirement of the Lorentz transformation and the Lorentz group, it is assumed in its derivation. Reciprocity is what forces the paradox to happen. Reciprocity is not one of the postulates of SR. It is an assumption that reciprocity is required for "The laws of physics to remain invariant in all inertial reference frames". However, it is trivial to show that the law of physics remain unchanged, even when the flat Minkowski metric is transformed by a constant coefficient "A", in such a way that;
ds2 = (1/A)*c2dt2 - A*(dx2 + dy2 + dz2)
Resulting in a scaled system of units where "force" is an invariant wrt the constant "A". Leaving all physical laws and experimental data, including EM fields unchanged, but the transformation from A=1 to A>1 is not reciprocal. In the latter time is slow, in the former it's not. No reciprocity, no paradox. IMO this too is the result of the Equivalence principle, when one body accelerates to velocity v=0.6c and the other does not. The end result is not reciprocal.
As far as I'm concerned, until someone shows evidence of reciprocity, it is by no means proven.
I would be interested to see the rate at which a clock on a space probe ticks that moves to reduce the dipole shift of the CMB as opposed to a clock on a probe which moves to increase the CMB dipole shift. I would wonder if it would be similar to the planes that when moving around the earth in the direction of earth rotation as opposed to a plane moving to oppose earth rotation.
Considering the Hafele–Keating experiment in a frame of reference at rest with respect to the center of the earth, a clock aboard the plane moving eastward, in the direction of the Earth's rotation, had a greater velocity (resulting in a relative time loss) than one that remained on the ground, while a clock aboard the plane moving westward, against the Earth's rotation, had a lower velocity than one on the ground.
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You look for a resolution?
Here we have one:
Our space-time has three space dimensions, it means that "physical objects" are distributed on a 3-brane.
General Relativity needs 4 dimensions, it means that an infinite number of 3-branes can be piled up one over the other along the 4th dimension without us observing this possibility by our eyes.
At relativistic speed it is possible to move into these parallel branes.
It seems that all logical paradoxes of relativity are resolved if this possibility is real.
The actual mechanism has been discussed here:
http://aip.scitation.org/doi/10.1063/1.1867271
Available on ArXiv.
Comments?
I have one: the theory is correct, our present ability to observe reality is very limited...
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The Hafele and Keating experiment supports no-reciprocity. Even the Michelson-Moorley experiment does not demonstrate reciprocity.
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Reciprocity is a requirement of the Lorentz transformation and the Lorentz group, it is assumed in its derivation. Reciprocity is what forces the paradox to happen. Reciprocity is not one of the postulates of SR. It is an assumption that reciprocity is required for "The laws of physics to remain invariant in all inertial reference frames". However, it is trivial to show that the law of physics remain unchanged, even when the flat Minkowski metric is transformed by a constant coefficient "A", in such a way that;
ds2 = (1/A)*c2dt2 - A*(dx2 + dy2 + dz2)
Resulting in a scaled system of units where "force" is an invariant wrt the constant "A". Leaving all physical laws and experimental data, including EM fields unchanged, but the transformation from A=1 to A>1 is not reciprocal.
Please demonstrate that this is actually consistent with the Michelson Morley experiment. It seems that anything other than A = constant would basically say that you are no longer dealing with flat spacetime. Michelson Morley experiment, Hafele-Keating, and general synchronization of atomic clocks on the surface of the Earth (and with those on GPS satellites) demonstrate the accuracy of the special relativity portion of time dilation that has A be a constant equal to 1. If you think otherwise, demonstrate how this could possibly not be the case and explain the results of all of these using a variable A between different inertial reference frames.
Possibly the clearest demonstration is in the decay times of moving particles. Particles moving in opposing directions in the lab frame would be measured to have different decay times if reciprocity was not true. (If reciprocity was not true then the 2 particles would not see symmetrically the same behavior from the other particle. This would then clearly translate to non-symmetric measurements of them in the lab frame.) Instead experiments all confirm decay times to be dilated consistent with relativity.
Also, units of force scaling consistently does not mean that all the other units do. You made similar claims earlier in the thread, and I demonstrated that other units like velocity did not scale consistently in your system.
In the latter time is slow, in the former it's not. No reciprocity, no paradox.
Your last sentence is simply a logical fallacy. Just because reciprocity results in a paradox, does not mean lack of reciprocity can't also result in a paradox. Looking it up, this fallacy is common enough someone gave it its own name: https://en.wikipedia.org/wiki/Denying_the_antecedent
As I have explained before, general relativity and curved spacetime reduce to special relativity in flat spacetime. since things are nice and smooth, slightly curved spacetime will behave very similarly to flat spacetime. If you are lucky, this reduces the amount of time travel in the paradox, but it wouldn't just make it instantly all go away. In fact there are quite a few solutions to general relativity known to be able to produce closed timelike curves.
As far as I'm concerned, until someone shows evidence of reciprocity, it is by no means proven.
You have not described what the requirements of such an experiment are. As far as I can tell the listed experiments should cover any reasonable requirements, but it appears you are choosing to not fully consider them because you refuse to accept that flat spacetime is inherently reciprocal.
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You look for a resolution?
Here we have one:
Our space-time has three space dimensions, it means that "physical objects" are distributed on a 3-brane.
General Relativity needs 4 dimensions,
Spacetime is 4 dimensions not 3. There are 3 spatial dimensions and time. And time is the 4th dimension in GR. GR does not require any dimensions beyond this.
If you actually read what you linked you would see the same thing I just said. What they are proposing is a 5th dimension on top of the 4 we are familiar with.
Anyway, I believe "FTL drops you off in another universe" has been suggested a couple times in this thread as a resolution. Presumably any such models would require that attempts at using this to time travel would just end up with you in a different universe.
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"FTL drops you off in another universe" looks like a good answer.
Having x, y, z filled with matter and t almost empty except for t=present time looks like a waste of resources.
In addition "something" should leak out because of quantum indeterminacy.
So if this is true the problem is resolved.
BTW the linked paper says: "To ensure agreement with these data and to keep a full agreement with the well-known Special Relativity, the proposed model changes our view of reality by giving to “time” the secondary role of derived coordinate. The overall number of fundamental large dimensions is still equal to the observed four, which have now the properties of spatial dimensions."
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Having x, y, z filled with matter and t almost empty except for t=present time looks like a waste of resources.
Even if this was true, it wouldn't make sense to call it a waste of resources. If there is an object at coordinates (x,y,z,t) = (1,2,3,0) (in some arbitrary coordinate system) and then that object moves so that at t = 10, its coordinates are (5,6,7,10). The answer to the question what is at the spacetime coordinates (1,2,3,0) the answer is still "that object"
BTW the linked paper says: "To ensure agreement with these data and to keep a full agreement with the well-known Special Relativity, the proposed model changes our view of reality by giving to “time” the secondary role of derived coordinate. The overall number of fundamental large dimensions is still equal to the observed four, which have now the properties of spatial dimensions."
I had only read the abstract of the paper which seemed fine. Looking at the rest, it does not actually support most of its arguments. It does not actually add an extra dimension, but tries to swap the roles of the invariant spacetime interval and time. This does not do what they claim, or really make any sense at all.
They also say:
Despite its success, SR is often affected by ambiguities of interpretation of the results.
They do not actually list a single example where this is true, and I know of no such case. There are results that are unintuitive, but the unituitive results have been experimentally confirmed which they even stated in the previous sentence.
Their conclusions paragraph goes even more off the rails, claiming that there are only 4 "electromagnetically orthogonal" spacetimes, despite never even having defined that term, and the fact that they clearly need an infinite number of "universes" for their theory to hold water.
And then they say:
Gravitational phenomena can allow navigation in the 4-space and, as soon as technology will permit, it will be possible to discover the possible real existence and nature of the remaining three space-times.
This is the part where in a consistent paper, they would be stating exactly what experiment would need to be done to demonstrate their theory is correct. Technological limitations are irrelevant.
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You look for a resolution?
Here we have one:
Our space-time has three space dimensions, it means that "physical objects" are distributed on a 3-brane.
General Relativity needs 4 dimensions,
Spacetime is 4 dimensions not 3. There are 3 spatial dimensions and time. And time is the 4th dimension in GR. GR does not require any dimensions beyond this.
If you actually read what you linked you would see the same thing I just said. What they are proposing is a 5th dimension on top of the 4 we are familiar with.
Anyway, I believe "FTL drops you off in another universe" has been suggested a couple times in this thread as a resolution. Presumably any such models would require that attempts at using this to time travel would just end up with you in a different universe.
Time as the Fourth dimension confuses me. In the three spatial dimensions, A co-ordinate (x,y,z) can be defined regardless of the inertial reference frame you are in. Yet, by the same rules, time cannot be given a particular co-ordinate point, as there is no "Universal Time", and ll time is relative to the particular inertial reference frame from which it is being measured.
How can you define a co-ordinate system without any fixed co-ordinates (along the time axis)?
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Time as the Fourth dimension confuses me. In the three spatial dimensions, A co-ordinate (x,y,z) can be defined regardless of the inertial reference frame you are in. Yet, by the same rules, time cannot be given a particular co-ordinate point, as there is no "Universal Time", and ll time is relative to the particular inertial reference frame from which it is being measured.
How can you define a co-ordinate system without any fixed co-ordinates (along the time axis)?
It is no different than picking the x, y, and z coordinates. All space is just as relative to the particular inertial coordinate system as time is.
If you are having trouble recognizing time as a valid dimension, you should first think about it from the perspective of Galilean relativity rather than special relativity.
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Tests of time dilation using particle lifetimes are comparisons while in flight. The most basic test of the symmetry described by special relativity is the Michelson Morley experiment. Can you describe a theory that can accurately predict the results of the above experiments and Michelson Morley, yet diverges for some other test of symmetry?
Otherwise you are just asking for a wild goose chase, since these experiments solidly confirm the symmetry of special relativity.
In which case, when it stops accelerating it is at a lower gravitational potential than where it started from.
An object can be accelerated from the ground to Earth orbit, or from Earth orbit to the ground. How exactly can you say that the end result of an acceleration results in a lower gravitational potential in general?
To put things another way: the acceleration only is producing the same time dilation as being stationary in a gravitational field while the acceleration is happening. This different time dilation is what makes the difference between the twins in the "twin paradox" which can be solved using Lorentz transformations. Your description of an accelerated object ending up in a lower gravitational potential does not make sense here.
The issue is about "Reciprocity" not symmetry.
This page, https://en.wikipedia.org/wiki/Time_dilation (https://en.wikipedia.org/wiki/Time_dilation) has a well written section on Reciprocity in SR, "velocity time dilation". Then in the next section on Gravitational time dilation it says;
"Contrarily to velocity time dilation, in which both observers measure the other as aging slower (a reciprocal effect), gravitational time dilation is not reciprocal. This means that with gravitational time dilation both observers agree that the clock nearer the center of the gravitational field is slower in rate, and they agree on the ratio of the difference."
The Hafele and Keating experiment supports no-reciprocity. Even the Michelson-Moorley experiment does not demonstrate reciprocity. So far, I have not found any experimental evidence to support a reciprocity effect. Gravitational time dilation is the result of the Equivalence principle alone, not any particular solution of GR.
Reciprocity is a requirement of the Lorentz transformation and the Lorentz group, it is assumed in its derivation. Reciprocity is what forces the paradox to happen. Reciprocity is not one of the postulates of SR. It is an assumption that reciprocity is required for "The laws of physics to remain invariant in all inertial reference frames". However, it is trivial to show that the law of physics remain unchanged, even when the flat Minkowski metric is transformed by a constant coefficient "A", in such a way that;
ds2 = (1/A)*c2dt2 - A*(dx2 + dy2 + dz2)
Resulting in a scaled system of units where "force" is an invariant wrt the constant "A". Leaving all physical laws and experimental data, including EM fields unchanged, but the transformation from A=1 to A>1 is not reciprocal. In the latter time is slow, in the former it's not. No reciprocity, no paradox. IMO this too is the result of the Equivalence principle, when one body accelerates to velocity v=0.6c and the other does not. The end result is not reciprocal.
As far as I'm concerned, until someone shows evidence of reciprocity, it is by no means proven.
I guess I know Puthoff wrote this equation this way. https://scholar.google.com/scholar?cluster=17157422968110203841&hl=en&as_sdt=0,26
ds2 = (1/K)*c2dt2 - K*(dx2 + dy2 + dz2)
where A=K
I am not sure why he converts c_o*t_o to c*t/K when it seems the conversion should be K*c=c_o and t*sqrt(K)=t_o so c_o*t_o=c*t*K .
However, I found it a bit easier to think of it in terms of the shrunken ruller. For the distance that light traverses over a time in a polarized vacuum greater than 1 or K>1 . (c2/K2)(t2*K)=(c*t)2/K . In that space a person with a ruler measures light but their ruler shrinks by Puthoff's equatons such that dx2/K is the non local length of the persons modified ruler. As a result their ruler scales exactly with the distance traversed by light so that they measure the same exact local speed of light as a person with a non-contracted ruler.
This of course scales the metric such that the metric near gravitational sources shrinks. The gradient in the metric forces a curvature on space and time.
For a non gravitational source that accelerates to reach some relativistic velocity it should gain effective mass , slow in time, and experience length contraction. In their immediate local metric they might even measure the speed of light and still observe a constant speed though with extra Doppler shifting. With Doppler shifting do we have conserved force from photons?
Along with a constant measured speed of light we have other conserved quantities such as Force and something else I am forgetting. Momentum? :(
This modification of their local metric seems to suggest a frame in which their ruler is normal to a distant observer. Accelerated objects gaining in energy and actually traveling through time unlike non-accelerated objects and hence the twin paradox.
In the case of the plane that moves in the opposite direction of rotation of the earth, it actually decelerates to a lower velocity to go around the earth. As a result its clock speeds up instead of slowing down. Hence my curiosity about a distant space probe moving to reduce the dipole shift of the cmb, away from our local vacuum.
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Time as the Fourth dimension confuses me. In the three spatial dimensions, A co-ordinate (x,y,z) can be defined regardless of the inertial reference frame you are in. Yet, by the same rules, time cannot be given a particular co-ordinate point, as there is no "Universal Time", and ll time is relative to the particular inertial reference frame from which it is being measured.
How can you define a co-ordinate system without any fixed co-ordinates (along the time axis)?
Ask Heisenberg.
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Time as the Fourth dimension confuses me. In the three spatial dimensions, A co-ordinate (x,y,z) can be defined regardless of the inertial reference frame you are in. Yet, by the same rules, time cannot be given a particular co-ordinate point, as there is no "Universal Time", and ll time is relative to the particular inertial reference frame from which it is being measured.
How can you define a co-ordinate system without any fixed co-ordinates (along the time axis)?
Ask Heisenberg.
It isn't really that confusing. Time is variable in the rate at which is passes. Distance is also variable in the rate at which is passes. As the universe has freedom in dimension at which objects move through space it also has some freedom to change the rate at which time passes.
Did you know the magnetic field would not exist were it not for this freedom? Let us say the current in an observing magnet travels in circles. Current is made up of charges and one charge in the observing magnet sees the current circling in the other magnet. This observing charge sees current in the opposite magnet is moving in the opposite direction as it is. By relativity charges moving in the opposite direction are slowed in time so move slower. This observing charge sees other charges in the other magnet as moving with it. These charges moving with the observing charge by relativity move faster in time, so these charges spend less time existing where they move faster and more time where they move slower.
Only the negative charges are moving in the circle so it is the negative charges that spend more time where time is perceived to be slower. The positive charges are not moving in a circle so they remain evenly distributed around the cricle. This creates a dipole field but this dipole field changes depending on the observing charge.
http://www.spacetimetravel.org/tompkins/node7.html
(http://images.iop.org/objects/asia/news/thumb/3/8/2/Figure2.jpg)
This is exactly what a magnetic field is, a dipole electric field that changes depending on the observing charge. Magnetic field lines are the electric potential lines. A velocity dependent (direction and magnitude) dipole electric field - perpendicular to the potential lines. The magnetic field is actually a relativistic electric field. The magnetic field describes the relativistic aspects of the electric field and the standard electric field is used to describe the non-relativistic aspects.
Now is there some deeper meaning to the rate of time passing being a variable? Possibly but the fact that it has a degree of freedom makes it an extra dimension.
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The issue is about "Reciprocity" not symmetry.
This page, https://en.wikipedia.org/wiki/Time_dilation (https://en.wikipedia.org/wiki/Time_dilation) has a well written section on Reciprocity in SR, "velocity time dilation". Then in the next section on Gravitational time dilation it says;
"Contrarily to velocity time dilation, in which both observers measure the other as aging slower (a reciprocal effect), gravitational time dilation is not reciprocal. This means that with gravitational time dilation both observers agree that the clock nearer the center of the gravitational field is slower in rate, and they agree on the ratio of the difference."
The Hafele and Keating experiment supports no-reciprocity. Even the Michelson-Moorley experiment does not demonstrate reciprocity. So far, I have not found any experimental evidence to support a reciprocity effect. Gravitational time dilation is the result of the Equivalence principle alone, not any particular solution of GR.
Reciprocity is a requirement of the Lorentz transformation and the Lorentz group, it is assumed in its derivation. Reciprocity is what forces the paradox to happen. Reciprocity is not one of the postulates of SR. It is an assumption that reciprocity is required for "The laws of physics to remain invariant in all inertial reference frames". However, it is trivial to show that the law of physics remain unchanged, even when the flat Minkowski metric is transformed by a constant coefficient "A", in such a way that;
ds2 = (1/A)*c2dt2 - A*(dx2 + dy2 + dz2)
Resulting in a scaled system of units where "force" is an invariant wrt the constant "A". Leaving all physical laws and experimental data, including EM fields unchanged, but the transformation from A=1 to A>1 is not reciprocal. In the latter time is slow, in the former it's not. No reciprocity, no paradox. IMO this too is the result of the Equivalence principle, when one body accelerates to velocity v=0.6c and the other does not. The end result is not reciprocal.
As far as I'm concerned, until someone shows evidence of reciprocity, it is by no means proven.
I guess I know Puthoff wrote this equation this way. https://scholar.google.com/scholar?cluster=17157422968110203841&hl=en&as_sdt=0,26
ds2 = (1/K)*c2dt2 - K*(dx2 + dy2 + dz2)
where A=K
I am not sure why he converts c_o*t_o to c*t/K when it seems the conversion should be K*c=c_o and t*sqrt(K)=t_o so c_o*t_o=c*t*K .
However, I found it a bit easier to think of it in terms of the shrunken ruller. For the distance that light traverses over a time in a polarized vacuum greater than 1 or K>1 . (c2/K2)(t2*K)=(c*t)2/K . In that space a person with a ruler measures light but their ruler shrinks by Puthoff's equatons such that dx2/K is the non local length of the persons modified ruler. As a result their ruler scales exactly with the distance traversed by light so that they measure the same exact local speed of light as a person with a non-contracted ruler.
This of course scales the metric such that the metric near gravitational sources shrinks. The gradient in the metric forces a curvature on space and time.
...
Hi Dustin,
I used "A" to represent a constant, because "K = K(x,y,z,t)" should be reserved as a variable function of the coordinates. Some people around here don't like it when a redefine letters of the alphabet from one post to another. ::)
Look at it this way;
ds2 = (1/K)*c2dt2 - K*(dx2 + dy2 + dz2) = c2dt02 - (dx02 + dy02 + dz02)
Then you should see that space-time interval, ds2 does not change from flat space-time when Puthoff transforms length and time. It only affects the rulers and clocks.
What I'm trying to figure out is; that when accelerations are involved to change relative velocities, the equivalence principle breaks reciprocity in SR. The object has actually changed its relative potential, just like it would in a gravitational field. It is obvious when we use a turntable to do the experiment, but when objects are moving toward or away from each other, it's not so clear. What I need most is just more time to relax and think about this stuff. It's not high on my priority list right now.
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The issue is about "Reciprocity" not symmetry.
This page, https://en.wikipedia.org/wiki/Time_dilation (https://en.wikipedia.org/wiki/Time_dilation) has a well written section on Reciprocity in SR, "velocity time dilation". Then in the next section on Gravitational time dilation it says;
"Contrarily to velocity time dilation, in which both observers measure the other as aging slower (a reciprocal effect), gravitational time dilation is not reciprocal. This means that with gravitational time dilation both observers agree that the clock nearer the center of the gravitational field is slower in rate, and they agree on the ratio of the difference."
The Hafele and Keating experiment supports no-reciprocity. Even the Michelson-Moorley experiment does not demonstrate reciprocity. So far, I have not found any experimental evidence to support a reciprocity effect. Gravitational time dilation is the result of the Equivalence principle alone, not any particular solution of GR.
Reciprocity is a requirement of the Lorentz transformation and the Lorentz group, it is assumed in its derivation. Reciprocity is what forces the paradox to happen. Reciprocity is not one of the postulates of SR. It is an assumption that reciprocity is required for "The laws of physics to remain invariant in all inertial reference frames". However, it is trivial to show that the law of physics remain unchanged, even when the flat Minkowski metric is transformed by a constant coefficient "A", in such a way that;
ds2 = (1/A)*c2dt2 - A*(dx2 + dy2 + dz2)
Resulting in a scaled system of units where "force" is an invariant wrt the constant "A". Leaving all physical laws and experimental data, including EM fields unchanged, but the transformation from A=1 to A>1 is not reciprocal. In the latter time is slow, in the former it's not. No reciprocity, no paradox. IMO this too is the result of the Equivalence principle, when one body accelerates to velocity v=0.6c and the other does not. The end result is not reciprocal.
As far as I'm concerned, until someone shows evidence of reciprocity, it is by no means proven.
I guess I know Puthoff wrote this equation this way. https://scholar.google.com/scholar?cluster=17157422968110203841&hl=en&as_sdt=0,26
ds2 = (1/K)*c2dt2 - K*(dx2 + dy2 + dz2)
where A=K
I am not sure why he converts c_o*t_o to c*t/K when it seems the conversion should be K*c=c_o and t*sqrt(K)=t_o so c_o*t_o=c*t*K .
However, I found it a bit easier to think of it in terms of the shrunken ruller. For the distance that light traverses over a time in a polarized vacuum greater than 1 or K>1 . (c2/K2)(t2*K)=(c*t)2/K . In that space a person with a ruler measures light but their ruler shrinks by Puthoff's equatons such that dx2/K is the non local length of the persons modified ruler. As a result their ruler scales exactly with the distance traversed by light so that they measure the same exact local speed of light as a person with a non-contracted ruler.
This of course scales the metric such that the metric near gravitational sources shrinks. The gradient in the metric forces a curvature on space and time.
...
Hi Dustin,
I used "A" to represent a constant, because "K = K(x,y,z,t)" should be reserved as a variable function of the coordinates. Some people around here don't like it when a redefine letters of the alphabet from one post to another. ::)
Look at it this way;
ds2 = (1/K)*c2dt2 - K*(dx2 + dy2 + dz2) = c2dt02 - (dx02 + dy02 + dz02)
Then you should see that space-time interval, ds2 does not change from flat space-time when Puthoff transforms length and time. It only affects the rulers and clocks.
What I'm trying to figure out is; that when accelerations are involved to change relative velocities, the equivalence principle breaks reciprocity in SR. The object has actually changed its relative potential, just like it would in a gravitational field. It is obvious when we use a turntable to do the experiment, but when objects are moving toward or away from each other, it's not so clear. What I need most is just more time to relax and think about this stuff. It's not high on my priority list right now.
Doesn't the speed of light co=K*c such that c2ot2o = K*c2t2 Why not use co?
I have noticed during acceleration the tilting of the light cone happens during acceleration symbolizing travel through time as one passes through space. Their space axis now passes through time - their time axis now passes through space (space/time). The space axis always tilting up in time in the direction of travel. Time travel always being into the future it is the individual that accelerates that ages slower and travels into the future.
I would be curious however to explore 2 individuals who exist traveling through the universe at c/8. One leaves their sibling at c/8 and decelerates so their light cone is now normal traveling away from their sibling at c/8 but stationary w.r.t. the light cone (he should technically age faster now). - their light cone is not tilted while his siblings remains at c/8. However, now to get back the sibling that left must accelerate to exceed c/8. Now the sibling who left should technically age slower during this part of the trip. I suppose the answer should be in the math.
I would suppose that is just one perspective from a set frame. When they meet up their ages should be the same in all frames suggesting relativity may some what hide the concept of a frame with out a tilted light cone.
Edit: I think I see what is going on with Puthoff's S^2= metric. By using c instead of cK this equation describes the difference in distance slow light would traverse in the slower time as opposed to the distance the normal light traverses in slower time.
Mistake made fixed to show correct equation:
c(K)2dt(K)2 - (x[K]2+y[K]2+z[K]2) = c2dt2/K - (x2+y2+z2)*K =
c(K)2dt(K)2 - c2dt(K)2 = c2dt2/K - c2dt2K
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Look at it this way;
ds2 = (1/K)*c2dt2 - K*(dx2 + dy2 + dz2) = c2dt02 - (dx02 + dy02 + dz02)
Then you should see that space-time interval, ds2 does not change from flat space-time when Puthoff transforms length and time. It only affects the rulers and clocks.
Doesn't the speed of light co=K*c such that c2ot2o = K*c2t2 Why not use co?
...
The coordinate speed of light is found by setting ds2 = 0. The coordinate speed of light in the x direction would be;
cK = c/K = dx/dt
If you do it this way, you don't need c0. I find it confuses a lot of people if you us c = c0/K. It's best to be specific, or define a different variable, cK for the coordinate speed.
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....
c2dt(K)2 - (x[K]2+y[K]2+z[K]2) = c2dt2/K - (x2+y2+z2)*K
This is okay, but...
c2dt2/K - c(K)2dt(K)2 = c2dt2/K - c2dt2K
This makes no sense. c(K)2dt(K)2 = (cdt)2/K3,
assuming c(K) = c/K.
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Time as the Fourth dimension confuses me. In the three spatial dimensions, A co-ordinate (x,y,z) can be defined regardless of the inertial reference frame you are in. Yet, by the same rules, time cannot be given a particular co-ordinate point, as there is no "Universal Time", and ll time is relative to the particular inertial reference frame from which it is being measured.
How can you define a co-ordinate system without any fixed co-ordinates (along the time axis)?
Ask Heisenberg.
My apologies. I think I see what your talking about now. I am not sure this will help but maybe the magnetic field is a good way to visualize multiple probabilities in time. The magnetic field being velocity dependent (direction and magnitude.) . Relative velocity also has connections with changes in time. For a magnetic field it seems to represent multiple probabilities that might exist simultaneously. I.e. a dipole relativistic electric field that changes depending on the observer. This field appears to accommodate all observers such that a particular observation collapses that probability and gives an actual observation.
This field of probability accommodates all directions x,y,z velocity, and maybe charge. It does almost seem like multiple dimensions of possibility depending on the observer though unlike quantum I guess it isn't quite as random. Unless the observers location and momentum were uncertain dx*dp.
I have a tendency to want to think of quantum mechanics as a field of possibilities that exist simultaneously. Then when an observer interacts the field of probabilities collapses. Similar to the universe stitching up some uncertainty in time as to what actually happens. This to me almost suggest Wheeler-Feynman absorber theory or something similar to it. https://en.wikipedia.org/wiki/Wheeler%E2%80%93Feynman_absorber_theory
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....
c2dt(K)2 - (x[K]2+y[K]2+z[K]2) = c2dt2/K - (x2+y2+z2)*K
This is okay, but...
c2dt2/K - c(K)2dt(K)2 = c2dt2/K - c2dt2K
This makes no sense. c(K)2dt(K)2 = (cdt)2/K3,
assuming c(K) = c/K.
Ack! your right, I had it backwards. I should have written c(K)2dt(K)2 - c2dt(K)2 = c2dt2/K - c2dt2K
emphases on the 2nd speed of light being not a function of K.
Are you sure c(K)2dt(K)2 = (cdt)2/K3 ?
(https://latex.codecogs.com/gif.latex?\begin{matrix}&space;\Delta&space;t(K)=&space;\Delta&space;t&space;\sqrt{K}&space;\,\,\,\,&space;,&space;&&space;\Delta&space;r(K)=&space;\frac{\Delta&space;r}{\sqrt{K}}&space;\,\,\,\,,&space;&&space;\frac{\Delta&space;r(K)}{\Delta&space;t(K)}=\frac{\Delta&space;r}{\Delta&space;t\,K}=c(K)&space;\\&space;c(K)^{2}dt(K)^{2}=&space;c^{2}\,dt^2\,\frac{K}{K^{2}}&space;=&space;\frac{c^{2}dt^{2}}{K}\,\,\,\,&space;&&space;&&space;\end{matrix})
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....
c2dt(K)2 - (x[K]2+y[K]2+z[K]2) = c2dt2/K - (x2+y2+z2)*K
This is okay, but...
c2dt2/K - c(K)2dt(K)2 = c2dt2/K - c2dt2K
This makes no sense. c(K)2dt(K)2 = (cdt)2/K3,
assuming c(K) = c/K.
Ack! your right, I had it backwards. I should have written c(K)2dt(K)2 - c2dt(K)2 = c2dt2/K - c2dt2K
emphases on the 2nd speed of light being not a function of K.
Are you sure c(K)2dt(K)2 = (cdt)2/K3 ?
(https://latex.codecogs.com/gif.latex?\begin{matrix}&space;\Delta&space;t(K)=&space;\Delta&space;t&space;\sqrt{K}&space;\,\,\,\,&space;,&space;&&space;\Delta&space;r(K)=&space;\frac{\Delta&space;r}{\sqrt{K}}&space;\,\,\,\,,&space;&&space;\frac{\Delta&space;r(K)}{\Delta&space;t(K)}=\frac{\Delta&space;r}{\Delta&space;t\,K}=c(K)&space;\\&space;c(K)^{2}dt(K)^{2}=&space;c^{2}\,dt^2\,\frac{K}{K^{2}}&space;=&space;\frac{c^{2}dt^{2}}{K}\,\,\,\,&space;&&space;&&space;\end{matrix})
By your own equation above; dt(K)2 = dt2/K.
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Hi Dustin,
I used "A" to represent a constant, because "K = K(x,y,z,t)" should be reserved as a variable function of the coordinates. Some people around here don't like it when a redefine letters of the alphabet from one post to another. ::)
Look at it this way;
ds2 = (1/K)*c2dt2 - K*(dx2 + dy2 + dz2) = c2dt02 - (dx02 + dy02 + dz02)
Then you should see that space-time interval, ds2 does not change from flat space-time when Puthoff transforms length and time. It only affects the rulers and clocks.
What I'm trying to figure out is; that when accelerations are involved to change relative velocities, the equivalence principle breaks reciprocity in SR. The object has actually changed its relative potential, just like it would in a gravitational field. It is obvious when we use a turntable to do the experiment, but when objects are moving toward or away from each other, it's not so clear. What I need most is just more time to relax and think about this stuff. It's not high on my priority list right now.
I get it now. The dt and other dx are a functions of K where they are being operated on to put them in the non-variant form dto and dxo.
Something i notice that was interesting was that distance dx^2+dy^2+dz^2 being a ruler could be substituted by the speed of light over a passage of time.
When I played with the math:
(https://latex.codecogs.com/gif.latex?\begin{matrix}&space;S^2=c^{2}dt[K]^{2}/K-K\left(dx[K]^{2}+dy[K]^{2}+dz[K]^{2}\right)&space;\\&space;S^2=c^{2}dt[K]^{2}/K-K\left(c[K]^{2}dt[K]^{2}\right)&space;\\&space;S^2=\left(\frac{ct[K]}{\sqrt{K}}-\sqrt{K}c[K]t[K]\right)\left(\frac{ct[K]}{\sqrt{K}}+\sqrt{K}c[K]t[K]\right)&space;\\&space;\frac{i \psi}{dt[K]}=\left(\frac{ic\psi}{S\sqrt{K}}\pm&space;\frac{\sqrt{K}ic[K]\psi}{S}\right)&space;\end{matrix})
I may not have it quite right but it looks like we get something that almost looks like for the space term dx+dy+dz a retarded wave multiplied by an advanced wave. Or maybe a positive index wave multiplied by a negative index wave. This reminds me of Heidi Fearn's discussion a bit. https://www.youtube.com/watch?v=t0wmh6b9UQM
Not sure it would really indicate a retarded wave but it seemed interesting. Also interesting reguarding ftl communications if retarded waves can really exist but I am sure nature some how excludes their actual use for that.
Edit: Ok, I do like the standing waves a bit better and what Heidi describes does seem a lot like a standing wave. Standing waves do have the backwards propagating wave if allowed the time. Not sure it takes into account all the quantum phenomena. It might. She mentions the advanced and retarded waves concept she used to explain quantum phenomena in a paper about the "quantum eraser" mentioned at time stamp 25:20 https://www.youtube.com/watch?v=mliNE_B_vNQ
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Hi Dustin,
I used "A" to represent a constant, because "K = K(x,y,z,t)" should be reserved as a variable function of the coordinates. Some people around here don't like it when a redefine letters of the alphabet from one post to another. ::)
Look at it this way;
ds2 = (1/K)*c2dt2 - K*(dx2 + dy2 + dz2) = c2dt02 - (dx02 + dy02 + dz02)
Then you should see that space-time interval, ds2 does not change from flat space-time when Puthoff transforms length and time. It only affects the rulers and clocks.
What I'm trying to figure out is; that when accelerations are involved to change relative velocities, the equivalence principle breaks reciprocity in SR. The object has actually changed its relative potential, just like it would in a gravitational field. It is obvious when we use a turntable to do the experiment, but when objects are moving toward or away from each other, it's not so clear. What I need most is just more time to relax and think about this stuff. It's not high on my priority list right now.
I get it now. The dt and other dx are a functions of K where they are being operated on to put them in the non-variant form dto and dxo.
Something i notice that was interesting was that distance dx^2+dy^2+dz^2 being a ruler could be substituted by the speed of light over a passage of time.
When I played with the math:
(https://latex.codecogs.com/gif.latex?\begin{matrix}&space;S^2=c^{2}dt[K]^{2}/K-K\left(dx[K]^{2}+dy[K]^{2}+dz[K]^{2}\right)&space;\\&space;S^2=c^{2}dt[K]^{2}/K-K\left(c[K]^{2}dt[K]^{2}\right)&space;\\&space;S^2=\left(\frac{ct[K]}{\sqrt{K}}-\sqrt{K}c[K]t[K]\right)\left(\frac{ct[K]}{\sqrt{K}}+\sqrt{K}c[K]t[K]\right)&space;\\&space;\frac{i \psi}{dt[K]}=\left(\frac{ic\psi}{S\sqrt{K}}\pm&space;\frac{\sqrt{K}ic[K]\psi}{S}\right)&space;\end{matrix})
I may not have it quite right but it looks like we get something that almost looks like for the space term dx+dy+dz a retarded wave multiplied by an advanced wave. Or maybe a positive index wave multiplied by a negative index wave. This reminds me of Heidi Fearn's discussion a bit. ...
Not sure it would really indicate a retarded wave but it seemed interesting. Also interesting reguarding ftl communications if retarded waves can really exist but I am sure nature some how excludes their actual use for that.
It appears you're still doing the math wrong by confusing dt with dt0 and dx with dx0, etc... That's why you're getting weird results. Your second line is simply the flat metric, no dependence on K at all since they all cancel out. The 3rd and 4th line are just confused...
I don't need advanced waves. I consider them simply as partial reflections in the polarizable vacuum. An outgoing EM wave leaving a gravitational field is red-shifted because it's losing energy to partial reflections as the refractive index changes. These partial reflected waves behave the same as advanced waves would, and cause the same effects, or so I believe.
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Hey I think you guys should check the OP and maybe self moderate.
The goal is to explain how paradoxes are avoided. The paradoxes are simple so the answers should be similarly simple.
If you are hoping to sell someone a ticket on your FTL, and they ask what they actually experience, a face full of math are not going to be convincing.
The topic also is not about arguing an FTL theory is actually part of this universe. It is purely about whether you can explain what behaviour you are even talking about when you say "FTL".
We have basically one "Good enough for Science fiction" solution for avoiding FTL paradoxes at the moment: Treating the CMB rest frame as special or, I think equivalently, defining instantaneous according to the CMB temperature: for example, right now the CMB temperature is 2.725°. So long as any FTL trip takes you to a point where the universe is older, in the sense that the CMB temperature is even colder, I believe no paradox is possible.
Parallel universes are often brought up as a solution for FTL and time travel in general. Papers postulating parallel universes don't add anything to the conversation unless they describe what you actually experience when you try to implement a paradox.
I have not yet seen a clear description of what a universe with FTL made possible by parallel universes looks like. All I can surmise is that people who jump into their FTL ships drunk and shouting about what a bastard their granddad was tend to never be seen again, but also strangers occasionally pop in and kill innocent people for things they purportedly would have done in the future. Since every action has an aspect of this paradox, I expect you would have a universe where there is an entirely fuzzy relationship between people who enter FTL and people who exit it. Sometimes there are similarities. Sometimes people vanish. Sometimes people with no histories appear. It is not very satisfactory.
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On the OP original question, I think both WarpTech and meberbs are correct – to a certain extent. It is a matter of reference frame perspective.
Let me provide the following thought problem, to explain this.
We have two communication stations, one on Earth and one circling Sirius at 8.7 light years away. They are continuously transmitting data to each other. According to GR, each perceived the incoming transmission from the other planet as having occurred 8.7 years ago. Logs are kept for 20 years at both ends.
So far, so good.
Somebody builds some form of FTL ship on earth. It travels to Sirius, .7 years, with a complete log of the earth transmissions from before the departure date, back 20 years. (I am not looking at how, or the perspective if the occupants. One set of headaches at a time, please.)
The ship popped into existence at Sirius. Since it went FTL, did it travel backwards in time? It depends on your reference frame. According to the Earth reference frame, a ship left, period. No paradox. According to the Sirius reference frame, it did travel backwards in time, per GR, but it travelled backwards in time from the future! It went backwards in time from exactly 8 years in the future, with information from the future, by Sirius'es reference frame. Sirius now knows, in advance, what the signals are going to be incoming for the next 8 years. Once again, no paradox, and the backward in time requirement of GR is upheld.
The ship loads the tapes from Sirius for Sirius'es last 20 years of transmissions. It heads back to Earth, with the same .7 travel time.
Does it arrive before it left? Absolutely not! It arrives 1.4 years after it left, (.7 going, .7 coming back), with the next 8 years of Sirius'es transmissions, in hand. Once again the ship travelled backwards in time, from the future, from Earth's reference frame. No paradox. (The only way the ship could arrive before it left is if it took negative duration for the trip, i.e., if it arrived at Sirius before it left Earth, by Earth's own reference frame. That truly would be time travel. . .
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(I am not looking at how, or the perspective if the occupants. One set of headaches at a time, please.)
Agreed, significant confusion comes from doing that, and it is irrelevant at the moment.
Does it arrive before it left? Absolutely not! It arrives 1.4 years after it left, (.7 going, .7 coming back), with the next 8 years of Sirius'es transmissions, in hand. Once again the ship travelled backwards in time, from the future, from Earth's reference frame. No paradox.
Describing a situation that doesn't involve a paradox does not mean that there are no situations that involve a paradox.
(The only way the ship could arrive before it left is if it took negative duration for the trip, i.e., if it arrived at Sirius before it left Earth, by Earth's own reference frame. That truly would be time travel. . .
But there are many reference frames equally valid as the Earth frame that do see the trip as having a negative duration. You have provided no reason why someone in one of those equally valid frames passing by Sirius could not just use the same type of FTL drive in their frame to go to Earth carrying all of the records from the other ship. Since in that frame the Earth ship arrived at Sirius before it left, this ship can go forward in time while it travels FTL to Earth and still arrive before the Earth ship left. I did all of the relevant calculations earlier for this type of situation.
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(I am not looking at how, or the perspective if the occupants. One set of headaches at a time, please.)
Agreed, significant confusion comes from doing that, and it is irrelevant at the moment.
Does it arrive before it left? Absolutely not! It arrives 1.4 years after it left, (.7 going, .7 coming back), with the next 8 years of Sirius'es transmissions, in hand. Once again the ship travelled backwards in time, from the future, from Earth's reference frame. No paradox.
Describing a situation that doesn't involve a paradox does not mean that there are no situations that involve a paradox.
(The only way the ship could arrive before it left is if it took negative duration for the trip, i.e., if it arrived at Sirius before it left Earth, by Earth's own reference frame. That truly would be time travel. . .
But there are many reference frames equally valid as the Earth frame that do see the trip as having a negative duration. You have provided no reason why someone in one of those equally valid frames passing by Sirius could not just use the same type of FTL drive in their frame to go to Earth carrying all of the records from the other ship. Since in that frame the Earth ship arrived at Sirius before it left, this ship can go forward in time while it travels FTL to Earth and still arrive before the Earth ship left. I did all of the relevant calculations earlier for this type of situation.
In SR, time dilation as observed by two observers moving at constant relative velocity wrt each other is "reciprocal", meaning each observer sees the other's clock running slow. In GR, time dilation as observed by two observers at rest at different gravitational potentials is not reciprocal. The observer at a lower altitude sees the clock at a higher altitude run "fast" not slow. This is also the case when one observer is circling around the other observer at a constant angular speed, while the observer at the center is at rest in an inertial frame (feels no forces). The observer feeling the force pulling him in a circular motion, is observed to have a slower clock than the observer at the center. It is not reciprocal.
To my knowledge, there have been no experiments, no tests of SR that verify/prove reciprocity. It is a prediction of the mathematics when objects are moving toward or away from each other, but there is no physical evidence which proves it. Experiments so far have only shown non-reciprocity in the results. Meberbs assumes reciprocity is real and his assertions are based on this assumption. I for one do not agree.
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In SR, time dilation as observed by two observers moving at constant relative velocity wrt each other is "reciprocal", meaning each observer sees the other's clock running slow. In GR, time dilation as observed by two observers at rest at different gravitational potentials is not reciprocal. The observer at a lower altitude sees the clock at a higher altitude run "fast" not slow. This is also the case when one observer is circling around the other observer at a constant angular speed, while the observer at the center is at rest in an inertial frame (feels no forces). The observer feeling the force pulling him in a circular motion, is observed to have a slower clock than the observer at the center. It is not reciprocal.
It does not matter that the gravitational/acceleration effect on time dilation is not symmetric. General relativity still has time dilation due to relative velocities, and that part is still symmetric, and still means that FTL allows time travel.
Also, your description of someone circling someone at rest is incomplete. (For clarity I will refer to person A as the one in the center and B as circling.) A sees B's clock run slower, due to the fact that B is both moving and accelerating. B will not see A's clock running faster by the same amount, because the velocity portion of the time dilation is symmetric, and B sees A's clock moving at the difference between the acceleration and velocity effects.
This kind of thing is seen in GPS satellites where the clock speedup of the satellites from being further out of Earth's gravity well is reduced by the slowdown due to their relative velocity.
To my knowledge, there have been no experiments, no tests of SR that verify/prove reciprocity. It is a prediction of the mathematics when objects are moving toward or away from each other, but there is no physical evidence which proves it. Experiments so far have only shown non-reciprocity in the results. Meberbs assumes reciprocity is real and his assertions are based on this assumption. I for one do not agree.
False. Maybe you missed the last post on this topic that you never replied to. I am not basing this on any kind of assumption without experimental support. You simply cannot explain the experimental results without reciprocity.
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To my knowledge, there have been no experiments, no tests of SR that verify/prove reciprocity. It is a prediction of the mathematics when objects are moving toward or away from each other, but there is no physical evidence which proves it. Experiments so far have only shown non-reciprocity in the results. Meberbs assumes reciprocity is real and his assertions are based on this assumption. I for one do not agree.
False. Maybe you missed the last post on this topic that you never replied to. I am not basing this on any kind of assumption without experimental support. You simply cannot explain the experimental results without reciprocity.
False. Time dilation is caused by damping of the quantum wave functions as explained in my paper, published in the proceedings from Estes Park, last year. As long as you ignore this and the references it contains, there is no point in responding to you.
Simply put; A gravitational field around a planet size object has a greater damping factor near the surface than at higher altitude. A test clock in motion relative to this gravitational source, will have a higher damping factor than clock a rest relative to the source. As long as you consider the vacuum field and its relative damping factor, there is no time travel. Clocks tick at different rates due to the relative damping factor. Lorentz Transformations are only a description of what is observed due to the c being a local constant, they are not the cause of it.
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False. Time dilation is caused by damping of the quantum wave functions as explained in my paper, published in the proceedings from Estes Park, last year. As long as you ignore this and the references it contains, there is no point in responding to you.
You asked for experiments that show that time dilation in relativity works the way that relativity says it does. You have been provided with those experiments and explanations of them but you continue to ignore the results. You have not demonstrated any way that your claims that special relativity is wrong can be consistent with the results of these experiments.
Lorentz Transformations are only a description of what is observed due to the c being a local constant, they are not the cause of it.
Cause is irrelevant for this discussion, only the resulting behavior. I don't think you ever gave a clear answer to whether your theory produces the same results as General Relativity or not (at least at macroscopic scales that are relevant to this discussion). If it is the same results, then there is no need to discuss your theory, standard GR works perfectly well for this discussion. If not, then before you insist on discussing your theory, you need to work out how it can somehow still explain the experimental results that were listed.
Remember that I already demonstrated in this thread that your explanation of the "twin paradox" was inconsistent. When you did not understand a basic part of special relativity, I am not sure why you would think that your theory of quantum gravity would be consistent.
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False. Time dilation is caused by damping of the quantum wave functions as explained in my paper, published in the proceedings from Estes Park, last year. As long as you ignore this and the references it contains, there is no point in responding to you.
You asked for experiments that show that time dilation in relativity works the way that relativity says it does. You have been provided with those experiments and explanations of them but you continue to ignore the results. You have not demonstrated any way that your claims that special relativity is wrong can be consistent with the results of these experiments.
Lorentz Transformations are only a description of what is observed due to the c being a local constant, they are not the cause of it.
Cause is irrelevant for this discussion, only the resulting behavior. I don't think you ever gave a clear answer to whether your theory produces the same results as General Relativity or not (at least at macroscopic scales that are relevant to this discussion). If it is the same results, then there is no need to discuss your theory, standard GR works perfectly well for this discussion. If not, then before you insist on discussing your theory, you need to work out how it can somehow still explain the experimental results that were listed.
Remember that I already demonstrated in this thread that your explanation of the "twin paradox" was inconsistent. When you did not understand a basic part of special relativity, I am not sure why you would think that your theory of quantum gravity would be consistent.
The consistency of my "model" with GR is definitively spelled out with equations and examples in my paper, in the proceedings from Estes Park. I am not going to re-write it here for your convenience!!! Until you take the 20 minutes to read it, I ask that you stop the derogatory comments about a paper you have not read.
As to demonstrating consistency with the experiments, that will require another paper. It's not something I can explain in detail on a forum. I have better things to do with my time than write papers for someone who refuses to read them.
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Meberbs, I would like to “show my work” in my analysis.
1. At earth time “t”, there is a continuous stream of data going to Sirius. It arrives at Sirius 8.7 years later. This is standard Relativity.
2. At earth time “t prime”, which is exactly 8.7 years after earth time “t”, a FTL ship set out for Sirius. Its cargo is a complete transcript of all the transmission from earth to Sirius for 20 years, up to the moment that the FTL ship starts. The ship arrives at Sirius, .7 years from when it left earth.
3 At Sirius, the transcripts are matched up. They are found to be in sync, up to the current transmissions being received at Sirius, but the transmissions on the ship now have an extra 8 years worth of data, that has not been received by Sirius yet. (Earth time “t prime” - .7 years of transit equal 8 years) Under Relativity, where did this data come from?
4. From Sirius's reference frame, under Relativity, it could have only come from the future. 8 years from the future, to be precise. How could it get from the future to Sirius, at the time the data arrived at Sirius? It has to travel backward in time, from the future, exactly 8 years. This is the calculation required from Relativity, as you point out.
5. Here is where it gets tricky. Where is the future starting point? From Sirius's reference frame, it is 8 years in the future from the point where the ship, bearing the data, arrived. Yet the arrival time for the ship, at Sirius, is actually “in the future” to start with. Let me explain.
The data being received at Sirius from earth's beam is from the past. Exactly 8.7 years in the past. So when you match up the data, from the FTL ship, it is being done at a time 8 years in the future from when the data was sent from earth, via beam (at time “t”). It can't be any earlier, as the data to match with (from the earth beam) would not have arrived at Sirius yet for comparison. So upon the ship arriving at Sirius, it did so .7 years after it left earth at “t prime”, by Sirius's reference frame. It has to, for the comparison to match. (The ship left earth at “t prime” 8.7 years after the signals to be compared are transmitted. It takes 8.7 years for them to arrive from the transmission. For them to match, both data records have to be at the same place, at the same time, in order to be matched.) Note, 8 years in the “future”, from Sirius's reference frame, coincides with the departure of the ship, minus the transit time, in earth's reference frame.
6. From earth's reference frame, the results is very simple. The ship disappears. Period. There is no way to observe the ship, as any method of observation is limited by c. Assuming that the FTL ship arrived at Sirius, after .7 years transit, it could not be observed on earth for 8.7 +.7 years.
7. On the return to earth, everything applies the same way. The ship leaves Sirius, (with the Sirius's data transcripts) and returns to earth. It takes .7 years transit time. The ship is now perceived from earth's reference frame as returning from “the future”, coming backwards in time, as required by Relativity. It has 8 years of future data, just like when it arrived at Sirius. But it does not arrive before it left, because it left in the Sirius's reference frame, which would have to be perceived from the earth's reference frame as “the future”, the the amount of travel backwards in time cannot exceed the difference between the “distance” minus the transit time required.
Meberbs, I went to all this detail to try to determine exactly where the “point of asymmetry” between the two viewpoints arises. Thank you for your time.
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The consistency of my "model" with GR is definitively spelled out with equations and examples in my paper, in the proceedings from Estes Park. I am not going to re-write it here for your convenience!!! Until you take the 20 minutes to read it, I ask that you stop the derogatory comments about a paper you have not read.
The answer is either a yes or a no. If you don't show that the answer is in general a "yes" then the answer is no.
As to demonstrating consistency with the experiments, that will require another paper. It's not something I can explain in detail on a forum. I have better things to do with my time than write papers for someone who refuses to read them.
What you are saying here is that it is not consistent with general relativity, because if it was, you wouldn't need another paper to show its consistency with the listed experiments. Since you need another paper to do so, it is clear that the paper you have written does not answer the questions I asked. (Anyway, I have skimmed it, but it looked like you didn't actually answer the questions I have, which your statements here now confirm)
A paper showing that your model is consistent with basic tests of relativity is something you should want to write anyway if you actually care about your theory. The fact that I showed your explanation of a basic application of relativity (the "twin paradox") was inconsistent, means that you need to go back and update your model to account for what you learned in that discussion, and until you have done so, I don't know why I should spend time reviewing something that has known flaws.
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Meberbs, I would like to “show my work” in my analysis.
Your work is irrelevant, because as I already stated, you are not discussing a paradox causing situation, and I never stated that anything was wrong with your answers. I will use a couple things you mention to clarify some misunderstandings you seem to have.
2. At earth time “t prime”,
Please call this t2. When discussing special relativity, the prime notation is used for indicating a different reference frame, not time coordinates in the same reference frame. This is just for clarity in communication.
Under Relativity, where did this data come from?
4. From Sirius's reference frame, under Relativity, it could have only come from the future.
No. It came from a spacelike separated point that is undefined as being the past or future. Using the Earth's reference frame it came from 0.7 years in the past.
5. Here is where it gets tricky. Where is the future starting point? From Sirius's reference frame, it is 8 years in the future from the point where the ship, bearing the data, arrived.
No, Sirius (for purposes relevant to this example) is moving at the same speed as Earth, so Sirius's frame and the Earth frame are the same frame as far as relativity is concerned. You can define a frame with the same speed and a new origin at the ship's arrival at Sirius, which would just be a linear transformation of t' = t-0.7 years, x' = x - 8 light years. No special relativity involved.
The rest of your description is just you agreeing with this until you say:
Note, 8 years in the “future”, from Sirius's reference frame, coincides with the departure of the ship, minus the transit time, in earth's reference frame.
Which doesn't make sense, because as you just explained, the ship came from Sirius's past, not future.
7. On the return to earth, everything applies the same way. The ship leaves Sirius, (with the Sirius's data transcripts) and returns to earth. It takes .7 years transit time. The ship is now perceived from earth's reference frame as returning from “the future”, coming backwards in time,
No, that is not what relativity says. The ship is still starting from a frame with the same velocity, so it is still travelling forward in time just like it was during the journey out. To see travelling backwards in time, you would have to look at it from a frame that is travelling at some speed relative to the Earth.
Meberbs, I went to all this detail to try to determine exactly where the “point of asymmetry” between the two viewpoints arises. Thank you for your time.
The "point of asymmetry" as you call it arises from the problems that occur when you look at things from the perspective of some frame with a different relative velocity. As long as you don't consider a different rest frame, you are not actually applying relativity. Look at the examples I discussed early in this thread for how to do that.
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The consistency of my "model" with GR is definitively spelled out with equations and examples in my paper, in the proceedings from Estes Park. I am not going to re-write it here for your convenience!!! Until you take the 20 minutes to read it, I ask that you stop the derogatory comments about a paper you have not read.
The answer is either a yes or a no. If you don't show that the answer is in general a "yes" then the answer is no.
As to demonstrating consistency with the experiments, that will require another paper. It's not something I can explain in detail on a forum. I have better things to do with my time than write papers for someone who refuses to read them.
What you are saying here is that it is not consistent with general relativity, because if it was, you wouldn't need another paper to show its consistency with the listed experiments. Since you need another paper to do so, it is clear that the paper you have written does not answer the questions I asked. (Anyway, I have skimmed it, but it looked like you didn't actually answer the questions I have, which your statements here now confirm)
A paper showing that your model is consistent with basic tests of relativity is something you should want to write anyway if you actually care about your theory. The fact that I showed your explanation of a basic application of relativity (the "twin paradox") was inconsistent, means that you need to go back and update your model to account for what you learned in that discussion, and until you have done so, I don't know why I should spend time reviewing something that has known flaws.
The paper that shows the PV Model of GR is consistent with GR was written by Hal Puthoff. My equations for how the variable refractive index effects space-time are identical to his. The only mathematical difference is that I have the Schwarzschild solution for K where he has an exponential solution for K. Both have the same 1st order approximation which is all that is needed to prove consistency with multiple test of GR. For me to republish what he has already done several times over is simply redundant. Check the references in my paper, and those posted by @dustinthewind here in this thread.
For your convenience:
https://arxiv.org/pdf/gr-qc/9909037.pdf (https://arxiv.org/pdf/gr-qc/9909037.pdf)
What you're asking for is proof of consistency with the experiments of SR, but by your own assertion, if the model is consistent with GR is must be consistent with SR in the limit of applicability. My assertion is that there is no time travel because the gravitational field gives us a baseline for the rate of clocks, and time dilation is a physical effect caused by damping of the quantum wave functions, not geometry. Geometry is a description, not a cause. The description that includes time travel is a stretch of the imagination, not a physical reality.
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What you're asking for is proof of consistency with the experiments of SR, but by your own assertion, if the model is consistent with GR is must be consistent with SR in the limit of applicability.
Exactly, but just after you claim that your model is consistent with GR, you claim then claim something that contradicts relativity.
Also, it is not my assertion that GR reduces to SR in flat spacetime, but a fact that general relativity simply is an extension of special relativity, as stated by every intro to GR text I have ever seen for example: http://web.mit.edu/edbert/GR/gr1.pdf (see the second key point they mention)
My assertion is that there is no time travel because the gravitational field gives us a baseline for the rate of clocks,
GR does not do this, your assertion is false. It seems like you keep trying to treat GR as if it said that time dilation only comes from gravitational fields/acceleration, while ignoring that it still has time dilation due to relative velocity.
and time dilation is a physical effect caused by damping of the quantum wave functions, not geometry. Geometry is a description, not a cause.
As I already said, cause is irrelevant, only the measured effect.
The description that includes time travel is a stretch of the imagination, not a physical reality.
Physical reality is that the space between stars is relatively flat and special relativity is completely applicable. General relativity includes more ways to time travel than special relativity, not less.
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and time dilation is a physical effect caused by damping of the quantum wave functions, not geometry. Geometry is a description, not a cause.
As I already said, cause is irrelevant, only the measured effect.
The description that includes time travel is a stretch of the imagination, not a physical reality.
Physical reality is that the space between stars is relatively flat and special relativity is completely applicable. General relativity includes more ways to time travel than special relativity, not less.
When someone measures or demonstrates time travel, I will change my mind. Until then, there is no evidence of it. If GR and SR predict it, then it needs to be demonstrated or else Relativity is wrong - Period. My model does not predict it and yet is consistent with all the measurable effects of GR and SR.
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When someone measures or demonstrates time travel, I will change my mind. Until then, there is no evidence of it. If GR and SR predict it, then it needs to be demonstrated or else Relativity is wrong - Period. My model does not predict it and yet is consistent with all the measurable effects of GR and SR.
You are not making any sense. Time travel in special relativity requires FTL, and special relativity does not have a way to do FTL. General relativity does have ways to do FTL, and it predicts that they result in time travel, but all of the ones we know of also require things that to our knowledge are non-existent, such as negative mass. You are saying that you want a demonstration of something that is impossible before you believe that it is impossible. This is simply a contradiction.
If your model does not predict it, then contrary to your previous claims, your model is not consistent with relativity, because the time dilation in relativity has been demonstrated multiple ways by different experiments, and FTL = time travel is an inevitable consequence of this time dilation.
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When someone measures or demonstrates time travel, I will change my mind. Until then, there is no evidence of it. If GR and SR predict it, then it needs to be demonstrated or else Relativity is wrong - Period. My model does not predict it and yet is consistent with all the measurable effects of GR and SR.
You are not making any sense. Time travel in special relativity requires FTL, and special relativity does not have a way to do FTL. General relativity does have ways to do FTL, and it predicts that they result in time travel, but all of the ones we know of also require things that to our knowledge are non-existent, such as negative mass. You are saying that you want a demonstration of something that is impossible before you believe that it is impossible. This is simply a contradiction.
If your model does not predict it, then contrary to your previous claims, your model is not consistent with relativity, because the time dilation in relativity has been demonstrated multiple ways by different experiments, and FTL = time travel is an inevitable consequence of this time dilation.
Wow! I said; "When someone measures or demonstrates time travel, I will change my mind. Until then, there is no evidence of it." and somehow you interpreted that sentence to mean the exact opposite of what I said. I do NOT believe time travel is possible. It is impossible and until someone demonstrates it, I will continue to believe it is impossible.
If GR predict time travel, it is probably wrong about that. Which means that my model, which derives time dilation without time travel, is an improvement! It is consistent with all the "measurable" classical tests of GR that have been predicted, as demonstrated by Puthoff.
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Wow! I said; "When someone measures or demonstrates time travel, I will change my mind. Until then, there is no evidence of it." and somehow you interpreted that sentence to mean the exact opposite of what I said.
You said that GR is wrong unless someone demonstrates time travel, while ignoring that GR only predicts time travel if you allow things that enable FTL travel. You are contradicting yourself from one sentence to the next.
I do NOT believe time travel is possible. It is impossible and until someone demonstrates it, I will continue to believe it is impossible.
Then you must either demonstrate that fundamental and tested parts of GR are wrong, or admit that FTL is impossible.
If GR predict time travel, it is probably wrong about that. Which means that my model, which derives time dilation without time travel, is an improvement! It is consistent with all the "measurable" classical tests of GR that have been predicted, as demonstrated by Puthoff.
First, if you read the paper that you linked, you will see that your statements fall flat. The paper does not discuss gravitational radiation or frame dragging and admits as much. We have been through this discussion before, so you really shouldn't be repeating these false claims.
It is simply not possible to be consistent with general relativity in the various stated situations, and not also include the conclusion that FTL means time travel. This comes from a trivial part of special relativity. The model in Puthoff's paper does not avoid this, and whatever you have done in your model to come to a different conclusion indicates an inconsistency in your model. This is certainly related to the fact that when you tried to explain what happens in the "twin paradox" with your model, you ended up with a contradiction.
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Wow! I said; "When someone measures or demonstrates time travel, I will change my mind. Until then, there is no evidence of it." and somehow you interpreted that sentence to mean the exact opposite of what I said.
You said that GR is wrong unless someone demonstrates time travel, while ignoring that GR only predicts time travel if you allow things that enable FTL travel. You are contradicting yourself from one sentence to the next.
I do NOT believe time travel is possible. It is impossible and until someone demonstrates it, I will continue to believe it is impossible.
Then you must either demonstrate that fundamental and tested parts of GR are wrong, or admit that FTL is impossible.
If GR predict time travel, it is probably wrong about that. Which means that my model, which derives time dilation without time travel, is an improvement! It is consistent with all the "measurable" classical tests of GR that have been predicted, as demonstrated by Puthoff.
First, if you read the paper that you linked, you will see that your statements fall flat. The paper does not discuss gravitational radiation or frame dragging and admits as much. We have been through this discussion before, so you really shouldn't be repeating these false claims.
It is simply not possible to be consistent with general relativity in the various stated situations, and not also include the conclusion that FTL means time travel. This comes from a trivial part of special relativity. The model in Puthoff's paper does not avoid this, and whatever you have done in your model to come to a different conclusion indicates an inconsistency in your model. This is certainly related to the fact that when you tried to explain what happens in the "twin paradox" with your model, you ended up with a contradiction.
The contradiction you refer to arrises because you allow reciprocity in SR. I do not, so I do not see any contradiction and FTL does not equate to time travel UNLESS you allow reciprocity.
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The contradiction you refer to arrises because you allow reciprocity in SR. I do not, so I do not see any contradiction and FTL does not equate to time travel UNLESS you allow reciprocity.
Without that reciprocity in SR you will get different results with the twin paradox and so your theory is incompatible with SR. Since the whole disagreement seems to live here maybe the discussion should be limited to the twin paradox.
So is one twin really really older than the other or is the answer to that meaningless as SR claims? What experiment would determine the answer?
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The contradiction you refer to arrises because you allow reciprocity in SR. I do not, so I do not see any contradiction and FTL does not equate to time travel UNLESS you allow reciprocity.
And not allowing reciprocity leads to trivial contradictions in non-FTL situations. As I already explained, you cannot explain measurements such as the time dilation of fast moving particle decay times (or really any special relativistic effect) without reciprocity. Non-reciprocity means that there must be some reference frame with a velocity that is "special," And Michelson-Morley type experiments demonstrate that there is not a special reference frame.
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The contradiction you refer to arrises because you allow reciprocity in SR. I do not, so I do not see any contradiction and FTL does not equate to time travel UNLESS you allow reciprocity.
And not allowing reciprocity leads to trivial contradictions in non-FTL situations. As I already explained, you cannot explain measurements such as the time dilation of fast moving particle decay times (or really any special relativistic effect) without reciprocity. Non-reciprocity means that there must be some reference frame with a velocity that is "special," And Michelson-Morley type experiments demonstrate that there is not a special reference frame.
False. My model explains all of this very well.
1. Long flight time (slow decay) of fast moving particles is determined by time dilation. My model predicts time dilation due to increased damping of the quantum wave function for the particle that is fast moving wrt the sun or the earth. The motion of fast moving particles does not demonstrate reciprocity! It only demonstrates time dilation for the particle moving fast with respect to the center of the local gravitational field.
2. The Michelson-Morley experiment is resolved by length contraction in the direction of motion. My model predicts length contraction due to increased damping...etc. for the experiment moving wrt the sun or the earth. The MM experiment does not demonstrate reciprocity, it only demonstrates length contraction in the direction of motion relative to the center of the gravitational field.
"Thus for a co-ordinate system moving with the earth the mirror system of Michelson and Morley is not shortened, but it is shortened for a co-ordinate system which is at rest relatively to the sun.
— Albert Einstein, 1916"
The gravitational field of the galaxy, the sun and the earth set the relative baseline for the rate at which clocks tick and the length of a ruler. Proximity to, and motion relative to the source of this baseline gravitational field increases damping. There have been NO experiments done that are so far distant that the gravitational fields of the earth, the sun or the galaxy are irrelevant. There have been NO experiments that demonstrate reciprocity.
The rate at which clocks tick is determined by damping and cannot be independent of the local gravitational field. If you use SR where there is no gravitational field, you get bogus concepts such as reciprocity that leads to the bogus prediction of time travel. If you treat all flat space-times as equal, without accounting for their relative damping, you get the same bogus predictions out of GR. Flat space-time is simply a damping factor whose derivatives vanish. There are an infinite number of different damping factors that result in different conformal scaling of matter. GR ignores this. To my knowledge, conformal gravity and string theory do not. I'm doing my research so I can write a paper, but I also have a day job.
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1. Long flight time (slow decay) of fast moving particles is determined by time dilation. My model predicts time dilation due to increased damping of the quantum wave function for the particle that is fast moving wrt the sun or the earth. The motion of fast moving particles does not demonstrate reciprocity! It only demonstrates time dilation for the particle moving fast with respect to the center of the local gravitational field.
Read my previous post again, and remember that the lab frame is NOT at rest with respect to the Earth or the sun.
Possibly the clearest demonstration is in the decay times of moving particles. Particles moving in opposing directions in the lab frame would be measured to have different decay times if reciprocity was not true. (If reciprocity was not true then the 2 particles would not see symmetrically the same behavior from the other particle. This would then clearly translate to non-symmetric measurements of them in the lab frame.) Instead experiments all confirm decay times to be dilated consistent with relativity.
If what you are saying was true, there would be a significant difference between particles moving with or against the Earth's orbit due to their different velocities relative to the sun.
2. The Michelson-Morley experiment is resolved by length contraction in the direction of motion. My model predicts length contraction due to increased damping...etc. for the experiment moving wrt the sun or the earth. The MM experiment does not demonstrate reciprocity, it only demonstrates length contraction in the direction of motion relative to the center of the gravitational field.
Except length contraction in the direction of motion would yield different results in the Michelson Morley experiment depending on the direction of the arms, since the lab is not stationary with respect to the Earth or the sun. Try thinking about what the Michelson Morley experiment actually shows before your next post. (Hint: it involves things not changing with velocities relative to gravity wells or anything else.)
"Thus for a co-ordinate system moving with the [surface of the] earth the mirror system of Michelson and Morley is not shortened, but it is shortened for a co-ordinate system which is at rest relatively to the sun.
— Albert Einstein, 1916"
I added a few words since you seem to be misapplying Einstein's quote.
The gravitational field of the galaxy, the sun and the earth set the relative baseline for the rate at which clocks tick and the length of a ruler. Proximity to, and motion relative to the source of this baseline gravitational field increases damping. There have been NO experiments done that are so far distant that the gravitational fields of the earth, the sun or the galaxy are irrelevant. There have been NO experiments that demonstrate reciprocity.
Only if you ignore every experimental test of relativity. You have simply refused to accept the results, and acted like the results are different from what they actually are. You have been asked to describe an experiment that would settle reciprocity for you, and the only response you have given was asking for a demonstration of something that is impossible.
The rate at which clocks tick is determined by damping and cannot be independent of the local gravitational field.
Yet the velocity portion of time dilation on GPS satellites has no correlation with their velocity relative to the sun, despite being much deeper in the sun's gravitational field than the Earth's.
If you use SR where there is no gravitational field, you get bogus concepts such as reciprocity that leads to the bogus prediction of time travel. If you treat all flat space-times as equal, without accounting for their relative damping, you get the same bogus predictions out of GR.
You called it bogus, well you must be right then </sarcasm>
Seriously, this seems to come down to you not liking what reality says, but reality doesn't care. Experiments show that all spacetime is equivalent and not affected by what velocity you are moving relative to a gravity well. (Being in the gravity well to begin with does have an affect, but the velocity doesn't matter.)
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I don't have a lot of time to respond but wanted to say at least this. I know of one instance where the speed of light one way around the earth is faster than the speed of light the other way around the earth. This would be frame dragging. Locally this would seem so suggest some difference in the speed of light one way as opposed to the other. I still haven't really resolved how this doesn't suggest some frame of reference in this instance.
On the other hand this velocity difference via frame dragging is confusing for me. I thought c locally measured was constant and only the frequency changed.
I wanted to throw this out there also. If this damping effect matches relativity then how is it for a current in a coil in the lab frame forms a dipole electric field for a charge not in the lab frame. That is for electrons, moving with the moving observing charge, move faster in time, while on the return path, electrons in the coil move slower in time. This shifts around in orientation depending on the observers direction of velocity.
I.e. It should replicate the effects that create our magnetic fields is what I am suggesting.
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Seriously, this seems to come down to you not liking what reality says, but reality doesn't care. Experiments show that all spacetime is equivalent and not affected by what velocity you are moving relative to a gravity well. (Being in the gravity well to begin with does have an affect, but the velocity doesn't matter.)
Your comments show a severe misunderstanding on your part. You think that I'm saying there is an aether, and we can measure our speed relative to this aether and therefore, the results of the M-M experiment will change. I am NOT saying that! This is your misunderstanding.
We cannot measure speed relative to the vacuum EM ZPF. This has been proven. The field is proportional to ω3, as such, a Lorentz transformation leaves the field unchanged! Therefore, the M-M experiment is unaffected, it will never detect the velocity relative to the ZPF, and in my model, that means the gravitational field. Length contraction, regardless of the relative velocity or which direction it's moving, will prevent any measure of it. The M-M experiment will NOT measure a speed relative to an aether because there is no aether, there is a ZP EM field and, this result is guaranteed by the spectral energy density of the ZPF being proportional to ω3.
Got it?
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Your comments show a severe misunderstanding on your part. You think that I'm saying there is an aether, and we can measure our speed relative to this aether and therefore, the results of the M-M experiment will change. I am NOT saying that! This is your misunderstanding.
No, what you are saying is that time dilation is dependent on velocity relative to local gravitational wells, that is different from aether, but equally disproven by the M-M experiment.
The motion of fast moving particles does not demonstrate reciprocity! It only demonstrates time dilation for the particle moving fast with respect to the center of the local gravitational field.
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The MM experiment does not demonstrate reciprocity, it only demonstrates length contraction in the direction of motion relative to the center of the gravitational field.
Emphasis mine. I only took your words for what they said, and I never mentioned aether.
We cannot measure speed relative to the vacuum EM ZPF. This has been proven. The field is proportional to ω3, as such, a Lorentz transformation leaves the field unchanged!
But you are claiming that the Lorentz transformation is wrong every time that you claim that FTL can exist without allowing time travel because you think that reciprocity doesn't exist. The Lorentz transformation itself is inherently reciprocal and if you try to make it non-reciprocal, you quickly get contradictions.
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No, what you are saying is that time dilation is dependent on velocity relative to local gravitational wells, that is different from aether, but equally disproven by the M-M experiment.
How so? The spectral energy density associated with the sun's gravitational field ADDS to that of the earth's gravitational field. The spectral energy density is a scalar field in this situation. There are no vector components associated with it that would cause the M-M experiment to detect it. (I'm not considering frame dragging here) The whole experiment is immersed in the SUM of all the scalar fields in the solar system, and beyond, at that location. As far as the equipment is concerned, it exists in a uniform field with a spectral energy density ρ(ω).
We cannot measure speed relative to the vacuum EM ZPF. This has been proven. The field is proportional to ω3, as such, a Lorentz transformation leaves the field unchanged!
But you are claiming that the Lorentz transformation is wrong every time that you claim that FTL can exist without allowing time travel because you think that reciprocity doesn't exist. The Lorentz transformation itself is inherently reciprocal and if you try to make it non-reciprocal, you quickly get contradictions.
The Lorentz transformation is a valuable mathematical tool. The logic and math is correct. What is wrong is the assumption that it is based on, which is that all vacuums in flat space-time are identical and interchangeable. They are not. There can be an infinite number of flat space-times that have different vacuum spectral energy density ρ(ω), which results in matter (clocks and rulers) having a different conformal scale. In GR these would be different vacuum solutions of Einstein's equations for flat space-time, but most people ignore this possibility. A proper accounting of these differences in the vacuum energy density will allow us to properly determine whether a situation is reciprocal or not, and avoid time travel paradoxes when moving FTL.
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No, what you are saying is that time dilation is dependent on velocity relative to local gravitational wells, that is different from aether, but equally disproven by the M-M experiment.
How so? The spectral energy density associated with the sun's gravitational field ADDS to that of the earth's gravitational field. The spectral energy density is a scalar field in this situation. There are no vector components associated with it that would cause the M-M experiment to detect it. (I'm not considering frame dragging here) The whole experiment is immersed in the SUM of all the scalar fields in the solar system, and beyond, at that location. As far as the equipment is concerned, it exists in a uniform field with a spectral energy density ρ(ω).
Read the words that you wrote. You said that what matters is velocity relative to the center of the gravitational field. What you state here is correct in that it shows that your previous statements are nonsensical and wrong.
We cannot measure speed relative to the vacuum EM ZPF. This has been proven. The field is proportional to ω3, as such, a Lorentz transformation leaves the field unchanged!
But you are claiming that the Lorentz transformation is wrong every time that you claim that FTL can exist without allowing time travel because you think that reciprocity doesn't exist. The Lorentz transformation itself is inherently reciprocal and if you try to make it non-reciprocal, you quickly get contradictions.
The Lorentz transformation is a valuable mathematical tool. The logic and math is correct. What is wrong is the assumption that it is based on, which is that all vacuums in flat space-time are identical and interchangeable. They are not.
The assumptions are based on experiment.
There can be an infinite number of flat space-times that have different vacuum spectral energy density ρ(ω), which results in matter (clocks and rulers) having a different conformal scale. In GR these would be different vacuum solutions of Einstein's equations for flat space-time, but most people ignore this possibility. A proper accounting of these differences in the vacuum energy density will allow us to properly determine whether a situation is reciprocal or not, and avoid time travel paradoxes when moving FTL.
And within each of these possible flat space times, special relativity holds exactly, including prohibitions on FTL due to time travel. The asymmetric effects of gravity on time dilation are in addition to the symmetric effects that velocity has. For the examples of how FTL would enable time travel, the gravitational effects are negligible compared to the velocity effects.
You don't get to pick and choose when the Lorentz transformations apply.
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No, what you are saying is that time dilation is dependent on velocity relative to local gravitational wells, that is different from aether, but equally disproven by the M-M experiment.
How so? The spectral energy density associated with the sun's gravitational field ADDS to that of the earth's gravitational field. The spectral energy density is a scalar field in this situation. There are no vector components associated with it that would cause the M-M experiment to detect it. (I'm not considering frame dragging here) The whole experiment is immersed in the SUM of all the scalar fields in the solar system, and beyond, at that location. As far as the equipment is concerned, it exists in a uniform field with a spectral energy density ρ(ω).
Read the words that you wrote. You said that what matters is velocity relative to the center of the gravitational field. What you state here is correct in that it shows that your previous statements are nonsensical and wrong.
How so? Explain please, how choosing a reference frame from which to measure the relative velocity makes any difference to the M-M experiment? The velocity can be measured "relative to" the center of the earth, the center of the sun, the center of the galaxy, etc... The results of the experiment will be the same. What difference does it make to the outcome of the experiment, that I choose to say relative to the center of gravity?
Thank you.
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Read the words that you wrote. You said that what matters is velocity relative to the center of the gravitational field. What you state here is correct in that it shows that your previous statements are nonsensical and wrong.
How so? Explain please, how choosing a reference frame from which to measure the relative velocity makes any difference to the M-M experiment? The velocity can be measured "relative to" the center of the earth, the center of the sun, the center of the galaxy, etc... The results of the experiment will be the same. What difference does it make to the outcome of the experiment, that I choose to say relative to the center of gravity?
Thank you.
You were claiming that it only shows time dilation relative to the center of gravity. If you want to say the results are valid regardless of reference frame, you are accepting reciprocity. Choice of reference frame makes no difference in the M-M experiment under special relativity, but if you reject reciprocity, choice of reference frame matters.
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Read the words that you wrote. You said that what matters is velocity relative to the center of the gravitational field. What you state here is correct in that it shows that your previous statements are nonsensical and wrong.
How so? Explain please, how choosing a reference frame from which to measure the relative velocity makes any difference to the M-M experiment? The velocity can be measured "relative to" the center of the earth, the center of the sun, the center of the galaxy, etc... The results of the experiment will be the same. What difference does it make to the outcome of the experiment, that I choose to say relative to the center of gravity?
Thank you.
You were claiming that it only shows time dilation relative to the center of gravity. If you want to say the results are valid regardless of reference frame, you are accepting reciprocity. Choice of reference frame makes no difference in the M-M experiment under special relativity, but if you reject reciprocity, choice of reference frame matters.
This only proves that if the M-M experiment is done at the surface of the Earth, or where ever. The outcome is independent of what frame I observe it from. It says nothing about reciprocity.
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You were claiming that it only shows time dilation relative to the center of gravity. If you want to say the results are valid regardless of reference frame, you are accepting reciprocity. Choice of reference frame makes no difference in the M-M experiment under special relativity, but if you reject reciprocity, choice of reference frame matters.
This only proves that if the M-M experiment is done at the surface of the Earth, or where ever. The outcome is independent of what frame I observe it from. It says nothing about reciprocity.
I honestly can't tell which statement in my post the word "that" (bolded above) is referring to. (I am assuming the word "this" refers to the M-M experiment, but maybe you meant something else)
Whatever you were trying to say though, your last 2 sentences are contradictory. Being independent of frame leads directly to the Lorentz transforms, which are inherently reciprocal. Your previous attempts to explain how the experimental results don't show reciprocity included marking the rest frame of the local large mass as "special," despite the fact that this is inconsistent with the actual experimental results. You seem to have taken this back, so you now have no remaining arguments supporting your claim that the experiments that demonstrate reciprocity don't do so.
To repeat clearly, non-reciprocity by definition means that there is some special frame defined by some speed and velocity where time dilation is always relative to that frame. Without such a frame, there would be no way for everyone to agree on which clock is faster or slower, so you end up with reciprocity, where 2 observers moving separately each see the other's clock as moving slower. Experiments show that there is no such frame, so reciprocity holds.*
Rather than continuing to assert contradictory things, could you respond to at least one of the following?
-ppnl's suggestion to describe the concrete scenario of the "twin paradox" and how that can be consistent under non-reciprocity (just don't repeat your description from earlier in the thread that I showed to be inconsistent)
-The description of an experiment that could be used to demonstrate reciprocity to you.
-An actually consistent non-reciprocal explanation for existing experiments. (You recently tried and failed at this, so I recommend not this option.)
* There is a special position (the location of the mass for the example of the Schwarzschild solution) so that the gravitational portion of time dilation is non-reciprocal, everyone agrees on how deep they are in the gravity well, but this does not introduce a special frame for velocity.
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You were claiming that it only shows time dilation relative to the center of gravity. If you want to say the results are valid regardless of reference frame, you are accepting reciprocity. Choice of reference frame makes no difference in the M-M experiment under special relativity, but if you reject reciprocity, choice of reference frame matters.
This only proves that if the M-M experiment is done at the surface of the Earth, or where ever. The outcome is independent of what frame I observe it from. It says nothing about reciprocity.
I honestly can't tell which statement in my post the word "that" (bolded above) is referring to. (I am assuming the word "this" refers to the M-M experiment, but maybe you meant something else)
The word "that" is being used as a conjunction, not a pronoun. Have you ever watched the show "Monk"? You remind me of that guy. (Now I used "that" as a pronoun.) ;D
You obsess over precision in language and misinterpret anything that doesn't meet your expectations. You do this to everyone and it's very annoying.
I'll get to the rest of this later...
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You were claiming that it only shows time dilation relative to the center of gravity. If you want to say the results are valid regardless of reference frame, you are accepting reciprocity. Choice of reference frame makes no difference in the M-M experiment under special relativity, but if you reject reciprocity, choice of reference frame matters.
This only proves that if the M-M experiment is done at the surface of the Earth, or where ever. The outcome is independent of what frame I observe it from. It says nothing about reciprocity.
I honestly can't tell which statement in my post the word "that" (bolded above) is referring to. (I am assuming the word "this" refers to the M-M experiment, but maybe you meant something else)
The word "that" is being used as a conjunction, not a pronoun. Have you ever watched the show "Monk"? You remind me of that guy. (Now I used "that" as a pronoun.) ;D
You obsess over precision in language and misinterpret anything that doesn't meet your expectations. You do this to everyone and it's very annoying.
I'll get to the rest of this later...
I had considered that use of "that" as well, but "if the M-M experiment is done at the surface of the Earth" is a condition under which the experiment is performed, not something proven by anything, so I still have no idea what you are trying to say with that sentence. If you consider that sentence important you are going to have to explain it.
I am specifically trying to not misinterpret you which is why I stated exactly what I didn't understand. If you want me to understand what you are saying regardless of the words you write you are going to have to explain to me how to acquire psychic powers. If you are annoyed by me trying to have clear communication and avoid misunderstandings, then I have to ask if you care about clear communication. (You are simultaneously accusing me of misinterpretations and getting annoyed that I request clarification, so I really don't know what you expect.)
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I had considered that use of "that" as well, but "if the M-M experiment is done at the surface of the Earth" is a condition under which the experiment is performed, not something proven by anything, so I still have no idea what you are trying to say with that sentence. If you consider that sentence important you are going to have to explain it.
Rewrite: "The outcome of the M-M experiment is independent of the frame of reference from which it is observed."
Likewise, what is happening on earth "now" is independent of the frame of reference from which it is observed.
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I had considered that use of "that" as well, but "if the M-M experiment is done at the surface of the Earth" is a condition under which the experiment is performed, not something proven by anything, so I still have no idea what you are trying to say with that sentence. If you consider that sentence important you are going to have to explain it.
Rewrite: "The outcome of the M-M experiment is independent of the frame of reference from which it is observed."
Likewise, what is happening on earth "now" is independent of the frame of reference from which it is observed.
Thank you for the clarification.
Yes, and combined with the fact that the M-M results are constant regardless of time of day, season, etc. the results show that reference frames are all equivalent, which means Lorentz transformations, which means reciprocity. Therefore the experiment demonstrates reciprocity.
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I had considered that use of "that" as well, but "if the M-M experiment is done at the surface of the Earth" is a condition under which the experiment is performed, not something proven by anything, so I still have no idea what you are trying to say with that sentence. If you consider that sentence important you are going to have to explain it.
Rewrite: "The outcome of the M-M experiment is independent of the frame of reference from which it is observed."
Likewise, what is happening on earth "now" is independent of the frame of reference from which it is observed.
Thank you for the clarification.
Yes, and combined with the fact that the M-M results are constant regardless of time of day, season, etc. the results show that reference frames are all equivalent, which means Lorentz transformations, which means reciprocity. Therefore the experiment demonstrates reciprocity.
False. The M-M experiment can be done at different gravitational potentials, and this will not affect the outcome. Gravitational fields are not reciprocal. Therefore, as I said... The M-M experiment says nothing about reciprocity. Reciprocity has never been tested.
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False. The M-M experiment can be done at different gravitational potentials, and this will not affect the outcome. Gravitational fields are not reciprocal. Therefore, as I said... The M-M experiment says nothing about reciprocity. Reciprocity has never been tested.
See my above post with the difference between reciprocity of velocity while position is non-reciprocal.
The M-M experiment includes rotating the apparatus such that the arms have different orientations with respect to the current velocity relative to the sun/center of galaxy. For the same test with gravitational potential, you would need to change the gravitational potential applied to each arm. If you did so you would find the effective arm length changes and therefore be able to tell the existence of the gravitational potential gradient.
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False. The M-M experiment can be done at different gravitational potentials, and this will not affect the outcome. Gravitational fields are not reciprocal. Therefore, as I said... The M-M experiment says nothing about reciprocity. Reciprocity has never been tested.
See my above post with the difference between reciprocity of velocity while position is non-reciprocal.
The M-M experiment includes rotating the apparatus such that the arms have different orientations with respect to the current velocity relative to the sun/center of galaxy. For the same test with gravitational potential, you would need to change the gravitational potential applied to each arm. If you did so you would find the effective arm length changes and therefore be able to tell the existence of the gravitational potential gradient.
Sorry, I was specifically thinking of the experiment as it is done on the surface of the earth, where the gravitational acceleration is down, orthogonal to the plane of the experiment. Such as, testing at the top of Mt. Everest vs at the bottom of Death Valley. The outcome will be unaffected.
Reciprocity plays no role in the experiment. The outcome will be the same, regardless if Lorentz transforms are reciprocal or not. Therefore, the experiment doesn't test reciprocity at all.
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False. The M-M experiment can be done at different gravitational potentials, and this will not affect the outcome. Gravitational fields are not reciprocal. Therefore, as I said... The M-M experiment says nothing about reciprocity. Reciprocity has never been tested.
See my above post with the difference between reciprocity of velocity while position is non-reciprocal.
The M-M experiment includes rotating the apparatus such that the arms have different orientations with respect to the current velocity relative to the sun/center of galaxy. For the same test with gravitational potential, you would need to change the gravitational potential applied to each arm. If you did so you would find the effective arm length changes and therefore be able to tell the existence of the gravitational potential gradient.
Sorry, I was specifically thinking of the experiment as it is done on the surface of the earth, where the gravitational acceleration is down, orthogonal to the plane of the experiment. Such as, testing at the top of Mt. Everest vs at the bottom of Death Valley. The outcome will be unaffected.
Yes I understood that, and as I stated, the reason the results do not change is because you are not doing a test where the arms are at different gravitational potentials. Your argument that it does not test reciprocity because it doesn't detect the non-reciprocity of gravitational wells is invalid.
If there was non-reciprocity with velocity a single run of the M-M experiment would show it, the multiple runs to show reciprocity are to make sure you didn't get "lucky" the first time.
Reciprocity plays no role in the experiment. The outcome will be the same, regardless if Lorentz transforms are reciprocal or not. Therefore, the experiment doesn't test reciprocity at all.
The outcome shows that inertial reference frames are equivalent regardless of velocity, this directly leads to the Lorentz transformations, which are inherently reciprocal. It does not matter how many times you claim otherwise, you have no supporting argument, and are just ignoring what the results say.
Now, rather than continuing to repeatedly make the same incorrect claim as if it will become true through repetition, I had another post that you said you would get to later, how about you respond to that one, it would probably be more productive.
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I will respond to this.
* There is a special position (the location of the mass for the example of the Schwarzschild solution) so that the gravitational portion of time dilation is non-reciprocal, everyone agrees on how deep they are in the gravity well, but this does not introduce a special frame for velocity.
Consider a gravity well. It doesn't have to be a black hole, but whatever. There are twins hovering at the gravitational potential, Φ(R0) in separate identical ships.
One of the twins receives an impulse which imparts a momentum p, such that it's kinetic energy now equals its gravitational potential energy. In other words, he shuts down his engine and enters orbit around the center of gravity, at the radius R0. The twin in orbit is now following a geodesic path, so there is no force and no acceleration in this twin's frame of reference. The ship and the twin are in freefall.
This situation continues for who knows how long, and each time the two twins pass each other, they compare clocks. The one that is hovering is ageing faster than the one that is in orbit. There is no reciprocity in this situation. They both agree the one hovering is ageing faster than the one in orbit.
By the typical response to the twin paradox, the one accelerating should be younger. Here, the opposite is true. Why? Becuase it is the relative damping that determines the rate at which clocks tick. Since they are at the same gravitational potential, the field has the same density and at rest, it has the same damping factor. But the one who is in orbit now has a higher damping factor due to the added kinetic energy (velocity) imparted to it by the initial impulse, therefore the twin in orbit ages slower. To be accurate, it's not the velocity that matters but the "Jerk", which is approximated by; frequency squared times the velocity, which results in damping of the quantum oscillators. It's proportionality to velocity is inherent, but it's the Jerk term doing the damping. See Milonni sec. 5.4, last paragraph.
PS: I added Grammarly to my browser. Maybe it will help. ::)
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I will respond to this.
* There is a special position (the location of the mass for the example of the Schwarzschild solution) so that the gravitational portion of time dilation is non-reciprocal, everyone agrees on how deep they are in the gravity well, but this does not introduce a special frame for velocity.
Consider a gravity well. It doesn't have to be a black hole, but whatever. There are twins hovering at the gravitational potential, Φ(R0) in separate identical ships.
You know that the Schwarzschild solution applies to non-black holes too right? I never mentioned anything being a black hole.
One of the twins receives an impulse which imparts a momentum p, such that it's kinetic energy now equals its gravitational potential energy. In other words, he shuts down his engine and enters orbit around the center of gravity, at the radius R0. The twin in orbit is now following a geodesic path, so there is no force and no acceleration in this twin's frame of reference. The ship and the twin are in freefall.
This situation continues for who knows how long, and each time the two twins pass each other, they compare clocks. The one that is hovering is ageing faster than the one that is in orbit. There is no reciprocity in this situation. They both agree the one hovering is ageing faster than the one in orbit.
By the typical response to the twin paradox, the one accelerating should be younger. Here, the opposite is true.
No, the one that is accelerating is the one that is in orbit, and this is still consistent with the standard version of the twin paradox. The stationary twin is stationary because he has 2 forces applied to him, gravity and the rocket keeping him up. The other one can see that he is moving in a circle around the massive object, because his velocity (direction) is changing relative to it. This is not the closed elevator thought experiment, he can look and see the source of the gravitational field. He knows about being in a gravitational field and is accounting for it.
Lets consider another situation that we have actual data for, the GPS constellation. Using purely the time dilation due to gravitational potential, you can calculate that a clock at GPS altitude would run about 0.53 ns/s fast. If you calculate the expected clock slowdown due to special relativity, you get 0.08 ns/s. This totals 0.45 ns/s which matches what you calculate if you just use the full Schwarzschild metric to begin with.
You can try calculating what would be observed from the frame of an object in orbit, or from the frame of a distant observer whose relative velocity with respect to the massive object matches that of the instantaneous velocity of the object in orbit, but such calculations are difficult since they result in time dependent metrics. If you did all the work, you would be able to show that the velocity portion is reciprocal. The easiest way to see this is to take the case where you have a frame where the velocity relative to the massive object is sufficiently close to c that the time dilation from the gravity well is negligible in comparison. In this case, you simply recover special relativity with all of its symmetry.
PS: I added Grammarly to my browser. Maybe it will help. ::)
You might want to check if it is working, my browser pointed out a typo in your post ("becuase") I would be making such typos constantly if my browser didn't have auto spell check, and I still miss some. Also if it doesn't get confused by you using the technical definition of the word jerk I will be impressed.
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Here is an actual experiment with relativity that shows it is non symmetric. https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
Considering the Hafele–Keating experiment in a frame of reference at rest with respect to the center of the earth, a clock aboard the plane moving eastward, in the direction of the Earth's rotation, had a greater velocity (resulting in a relative time loss) than one that remained on the ground, while a clock aboard the plane moving westward, against the Earth's rotation, had a lower velocity than one on the ground.
2 aircraft flying in opposite directions on earth. Aircraft one, flying in the direction of the rotation of earth has its clock slowed the greatest. The clock on the ground is not as slow as aircraft 1 but is slower than aircraft 2. Aircraft 2's clock is the fastest as it moves the counter the earths rotation. Now take this path and reduce it to an instant in time with the two aircraft passing each other. One aircraft clock is running fast w.r.t. one plane while the other plane should see the others as slow. They quickly land and measure the smaller change in time via the shorter trip.
This appears to me to be non-symmetric. Oddly with respect to something that doesn't rotate and seems to be with respect to the earth center if this article is correct.
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I will respond to this.
* There is a special position (the location of the mass for the example of the Schwarzschild solution) so that the gravitational portion of time dilation is non-reciprocal, everyone agrees on how deep they are in the gravity well, but this does not introduce a special frame for velocity.
Consider a gravity well. It doesn't have to be a black hole, but whatever. There are twins hovering at the gravitational potential, Φ(R0) in separate identical ships.
You know that the Schwarzschild solution applies to non-black holes too right? I never mentioned anything being a black hole.
Obsessing over minutia again? It's insulting.
One of the twins receives an impulse which imparts a momentum p, such that its kinetic energy now equals its gravitational potential energy. In other words, he shuts down his engine and enters orbit around the center of gravity, at the radius R0. The twin in orbit is now following a geodesic path, so there is no force and no acceleration in this twin's frame of reference. The ship and the twin are in freefall.
This situation continues for who knows how long, and each time the two twins pass each other, they compare clocks. The one that is hovering is ageing faster than the one that is in orbit. There is no reciprocity in this situation. They both agree the one hovering is ageing faster than the one in orbit.
By the typical response to the twin paradox, the one accelerating should be younger. Here, the opposite is true.
No, the one that is accelerating is the one that is in orbit, and this is still consistent with the standard version of the twin paradox. The stationary twin is stationary because he has 2 forces applied to him, gravity and the rocket keeping him up. The other one can see that he is moving in a circle around the massive object, because his velocity (direction) is changing relative to it. This is not the closed elevator thought experiment, he can look and see the source of the gravitational field. He knows about being in a gravitational field and is accounting for it.
You have a strange notion of how the EEP works! ??? The twin in orbit is in free fall. By definition he is following a geodesic through space-time. There are no forces, no accelerations acting on him. He is in an inertial reference frame and he doesn’t need to close his eyes for this to be true. This is what the Math says under GR. This is where moving in a circle is equivalent to moving in a straight line in curved space-time.
"In the context of general relativity, where gravitation is reduced to a space-time curvature, a body in free fall has no force acting on it."
The twin in orbit was only accelerating for a tiny instant of time when the initial impulse gave his ship the kinetic energy and momentum to go into orbit at the same altitude as his brother. They don’t need to take the gravitational potential into account because they are both at the same potential. The only thing causing their clocks to disagree is the additional kinetic energy that was imparted to the orbiting twin, and it is inherently not reciprocal. It depends on the history. It was the orbiting twin that received the impulse and was raised to a higher energy state. Therefore his clock runs slower than his hovering twin. The twin that is hovering has been in a non-inertial reference frame the whole time, and his clock is running faster. The act of "turning around" that is usually credited as the solution to the twin paradox is inapplicable, and yet we have twins ageing at different rates in a steady state.
Lets consider another situation ...
Let's not. It doesn't help to complicate things. See the post above regarding the Hafele–Keating experiment. It supports the non-reciprocity of time dilation, though I don't think it's definitive. It would be better if they were orbiting clocks rather than aeroplanes. Then the two clocks flying in each direction would be in free fall.
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Consider a gravity well. It doesn't have to be a black hole, but whatever. There are twins hovering at the gravitational potential, Φ(R0) in separate identical ships.
You know that the Schwarzschild solution applies to non-black holes too right? I never mentioned anything being a black hole.
Obsessing over minutia again? It's insulting.
You brought up black holes for some reason, either you didn't know that the Schwarzschild solution covers planets and stars too, and I was providing information to make sure you knew what I was talking about, or you did know (and apparently thought I didn't) and I was letting you know that I was on the same page. So where exactly is the insult?
You have a strange notion of how the EEP works! ??? The twin in orbit is in free fall. By definition he is following a geodesic through space-time. There are no forces, no accelerations acting on him. He is in an inertial reference frame and he doesn’t need to close his eyes for this to be true. This is what the Math says under GR. This is where moving in a circle is equivalent to moving in a straight line in curved space-time.
I thought that your theory included interpreting the cause of GR effects as damping rather than space time curvature (And I do think that a non-curvature based interpretation of GR may aide creating a theory of quantum gravity) This is somewhat irrelevant pedantry though, so I'll try to restate the important point that I wanted to communicate:
The way gravity is treated in GR makes it easy to miscommunicate meaning when talking about words like acceleration. In the standard "twin paradox" it is the one that accelerates that ages slower. In the situation that you are describing, it seems clear that the definition of "one that accelerates" is "one with a non-constant velocity vector relative to a distant observer who is moving at constant velocity." The constantly changing velocity vector is the equivalent of turning around in the standard twin paradox, but the situation as described doesn't have any "non-accelerating" portions to clearly show the reciprocity.
The time dilation is purely related to the velocity, and the situation is replicated in special relativity by one person at rest, and another who flies in a big circle, but with no gravity present. It seems that you may be trying to apply the equivalence principle inside out, which is easy to do by accident. We agree on the answer though, and nothing about the situation you have described invalidates that relativity works and includes reciprocity.
Let's not. It doesn't help to complicate things.
I tried to give an example to show how general relativity has both gravitation potential and velocity based effects. if you think that complicates things, why don't we simplify things and you try to provide a consistent non-reciprocal explanation of what happens when you act out the twin paradox.
See the post above regarding the Hafele–Keating experiment. It supports the non-reciprocity of time dilation, though I don't think it's definitive. It would be better if they were orbiting clocks rather than aeroplanes. Then the two clocks flying in each direction would be in free fall.
I think I may understand the problem with your line of reasoning now. It seems like you think things are either reciprocal or non-reciprocal. If things were purely non-reciprocal then everyone would agree on the rate of time passing on everyone else's clocks. So if A thinks B's clock is at half speed, then B thinks that A's clock is at double speed. You keep taking any evidence that differs from perfect symmetry and jumping to this case.
The problem is that things don't have to be perfectly symmetric to include some reciprocity. A can think B's clock runs at half speed, while B thinks that A's clock runs at 2/3rds speed. (relative to each other, not to some distant observer)
The FTL resulting in time travel still happens in this scenario, and for the examples of paradox situations in this thread, gravitational wells involved produce very little time dilation compared to the velocities, to the extent they shouldn't have significant effect, maybe 50% vs 49% if that.
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Meberbs, I would like to “show my work” in my analysis.
Your work is irrelevant, because as I already stated, you are not discussing a paradox causing situation, and I never stated that anything was wrong with your answers. I will use a couple things you mention to clarify some misunderstandings you seem to have.
2. At earth time “t prime”,
Please call this t2. When discussing special relativity, the prime notation is used for indicating a different reference frame, not time coordinates in the same reference frame. This is just for clarity in communication.
Under Relativity, where did this data come from?
4. From Sirius's reference frame, under Relativity, it could have only come from the future.
No. It came from a spacelike separated point that is undefined as being the past or future. Using the Earth's reference frame it came from 0.7 years in the past.
5. Here is where it gets tricky. Where is the future starting point? From Sirius's reference frame, it is 8 years in the future from the point where the ship, bearing the data, arrived.
No, Sirius (for purposes relevant to this example) is moving at the same speed as Earth, so Sirius's frame and the Earth frame are the same frame as far as relativity is concerned. You can define a frame with the same speed and a new origin at the ship's arrival at Sirius, which would just be a linear transformation of t' = t-0.7 years, x' = x - 8 light years. No special relativity involved.
The rest of your description is just you agreeing with this until you say:
Note, 8 years in the “future”, from Sirius's reference frame, coincides with the departure of the ship, minus the transit time, in earth's reference frame.
Which doesn't make sense, because as you just explained, the ship came from Sirius's past, not future.
7. On the return to earth, everything applies the same way. The ship leaves Sirius, (with the Sirius's data transcripts) and returns to earth. It takes .7 years transit time. The ship is now perceived from earth's reference frame as returning from “the future”, coming backwards in time,
No, that is not what relativity says. The ship is still starting from a frame with the same velocity, so it is still travelling forward in time just like it was during the journey out. To see travelling backwards in time, you would have to look at it from a frame that is travelling at some speed relative to the Earth.
Meberbs, I went to all this detail to try to determine exactly where the “point of asymmetry” between the two viewpoints arises. Thank you for your time.
The "point of asymmetry" as you call it arises from the problems that occur when you look at things from the perspective of some frame with a different relative velocity. As long as you don't consider a different rest frame, you are not actually applying relativity. Look at the examples I discussed early in this thread for how to do that.
“The purpose of answers is to help us refine our questions.”
Meberbs, according to what you are saying, time at various FTL velocities (should they exist), causes a jump backwards in time, from almost the entire duration of the FTL trip, (at velocity just above c), and steadily dropping as the FTL velocity approaches infinity (instantaneous).
This strikes me as a strange discontinuity. (Graphing it also looks strange.)
Granted that for the purpose of Relativity there needs to be a negative sign, why must it be assigned to the time component? Could it not be assigned to the mass component? At this stage, with no way to experiment, why is there a preference?
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Meberbs, according to what you are saying, time at various FTL velocities (should they exist), causes a jump backwards in time, from almost the entire duration of the FTL trip, (at velocity just above c), and steadily dropping as the FTL velocity approaches infinity (instantaneous).
That doesn't sound like anything I have said.
What I said is that for an FTL jump that results in forward in time motion in the Earth frame will result in backwards in time motion in a reference frame moving sufficiently fast with respect to Earth. The closer to instantaneous the jump is from Earth's perspective, the more backwards in time it will appear to be from the same alternate reference frame. Similarly, the faster the FTL jump, the slower the other frame can be to see the jump as backwards in time motion.
It seems like you are making an assumption that "simultaneous" is something that doesn't change between reference frames. Observers moving at different velocities relative to each other do not ever agree on whether 2 events are simultaneous (unless the events are also co-located, but for the purpose of special relativity, that would make them the same event.).
Granted that for the purpose of Relativity there needs to be a negative sign, why must it be assigned to the time component? Could it not be assigned to the mass component? At this stage, with no way to experiment, why is there a preference?
Component of what with a negative sign? There is a negative sign attached to time in the metric, but there is no mass component in the metric to shift it to.
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You have a strange notion of how the EEP works! ??? The twin in orbit is in free fall. By definition, he is following a geodesic through space-time. There are no forces, no accelerations acting on him. He is in an inertial reference frame and he doesn’t need to close his eyes for this to be true. This is what the Math says under GR. This is where moving in a circle is equivalent to moving in a straight line in curved space-time.
I thought that your theory included interpreting the cause of GR effects as damping rather than space-time curvature (And I do think that a non-curvature based interpretation of GR may aide creating a theory of quantum gravity)
Interpreting is the keyword... Remember, any quantum gravity solution must be able to be interpreted as space-time curvature. The two interpretations are interchangeable.
This is somewhat irrelevant pedantry though, so I'll try to restate the important point that I wanted to communicate:
The way gravity is treated in GR makes it easy to miscommunicate meaning when talking about words like acceleration. In the standard "twin paradox" it is the one that accelerates that ages slower. In the situation that you are describing, it seems clear that the definition of "one that accelerates" is "one with a non-constant velocity vector relative to a distant observer who is moving at constant velocity." The constantly changing velocity vector is the equivalent of turning around in the standard twin paradox, but the situation as described doesn't have any "non-accelerating" portions to clearly show the reciprocity.
No, you're overthinking it. It is the one that has a higher energy content whose clock runs slower. Whatever frame you choose, the twins started in the same frame, at the same energy and "one" was given additional kinetic energy making his clock run slow. There is no reciprocity because the history of the situation is apparent and their clocks confirm it.
The time dilation is purely related to the velocity, and the situation is replicated in special relativity by one person at rest, and another who flies in a big circle but with no gravity present. It seems that you may be trying to apply the equivalence principle inside out, which is easy to do by accident. We agree on the answer though, and nothing about the situation you have described invalidates that relativity works and includes reciprocity.
I'm glad we agree. :) However, the situation is not the same as what you describe. Flying in a big circle requires forces acting on the ship/twin for the whole trip. This is equivalent to the twin hovering in my experiment. In your situation, the other twin at rest would age faster. In the situation which I described we have the opposite. It is the twin in the inertial frame in free fall that ages slower and the one accelerating (forces present) that ages faster.
See the attached image below. This is the crux of the issue I have with reciprocity.
The image shows in red, two clocks separated by some distance, (x2 - x1).
The clocks are at rest relative to each other and were synchronized in the past.
As long as nothing changes, (t = t' = Now) at both locations.
At any moment, an impulse is imparted to the clock at x2, causing it to move away from x1 at a constant velocity. These are the blue lines.
From your previous statements, you believe that after this impulse the situation is reciprocal. I say reciprocity in this situation is an illusion. It is not reciprocal because only the clock at x2 received an impulse.
After receiving the impulse, in the rest frame of the clock that started at x2. Looking behind it, it's x' axis (blue) which represents "Now" is directed into the past of the clock at x1. The longer the distance (x2 - x1), the farther into the past the axis extends. I say this is an illusion because the clock (and ruler) which started at x2 has been changed by the impulse it received. The clock at x1 didn't change and the impulse didn't suddenly give us access to the past, if and when FTL is possible.
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No, you're overthinking it. It is the one that has a higher energy content whose clock runs slower. Whatever frame you choose, the twins started in the same frame, at the same energy and "one" was given additional kinetic energy making his clock run slow. There is no reciprocity because the history of the situation is apparent and their clocks confirm it.
Except energy is frame dependent. In a frame based on a distant observer that is moving at the same instantaneous velocity as the orbiting twin, the orbiting twin is the one with less (0) kinetic energy. Your claim of "no reciprocity" ignores the existence of this frame.
The time dilation is purely related to the velocity, and the situation is replicated in special relativity by one person at rest, and another who flies in a big circle but with no gravity present. It seems that you may be trying to apply the equivalence principle inside out, which is easy to do by accident. We agree on the answer though, and nothing about the situation you have described invalidates that relativity works and includes reciprocity.
I'm glad we agree. :) However, the situation is not the same as what you describe. Flying in a big circle requires forces acting on the ship/twin for the whole trip. This is equivalent to the twin hovering in my experiment. In your situation, the other twin at rest would age faster. In the situation which I described we have the opposite. It is the twin in the inertial frame in free fall that ages slower and the one accelerating (forces present) that ages faster.
In both situations it is the twin that is moving in a circle as seen by a distant observer that ages slower. The situations are mathematically equivalent, yet you are insisting on defining your terms in such a way as to get an apparent contradiction.
See the attached image below. This is the crux of the issue I have with reciprocity.
The image shows in red, two clocks separated by some distance, (x2 - x1).
The clocks are at rest relative to each other and were synchronized in the past.
As long as nothing changes, (t = t' = Now) at both locations.
All of these statements are only true in one, ultimately arbitrary frame.
At any moment, an impulse is imparted to the clock at x2, causing it to move away from x1 at a constant velocity. These are the blue lines.
From your previous statements, you believe that after this impulse the situation is reciprocal. I say reciprocity in this situation is an illusion. It is not reciprocal because only the clock at x2 received an impulse.
And how would an observer coming in later know that that was the case and not that they had both started moving and the first clock had been slowed to a stop? Or if the observer who looks later happens to be moving with the same speed as the second clock, it is the first clock that they would see as moving and slowed.
After receiving the impulse, in the rest frame of the clock that started at x2. Looking behind it, it's x' axis (blue) which represents "Now" is directed into the past of the clock at x1. The longer the distance (x2 - x1), the farther into the past the axis extends. I say this is an illusion because the clock (and ruler) which started at x2 has been changed by the impulse it received. The clock at x1 didn't change and the impulse didn't suddenly give us access to the past, if and when FTL is possible.
Except there is nothing different between the 2 clocks, everything is exactly identical, and all of your conclusions are based on picking a preferred frame, but if you pick a preferred frame, you will no longer see the speed of light as constant in all frames.
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Except energy is frame dependent.
All energy gravitates. In that sense, it cannot be frame dependent when in a gravitational field because one clock/twin has the extra kinetic energy imparted to it and the other does not. Their gravitational attraction to the center of gravity will be different. Therefore, KE is not frame dependent when considering the gravitational effects of that energy. Time dilation is a gravitational effect based on the absolute energy content wrt the vacuum ZP energy, i.e., the gravitational field.
...In the situation which I described we have the opposite. It is the twin in the inertial frame in free fall that ages slower and the one accelerating (forces present) that ages faster.
In both situations, it is the twin that is moving in a circle as seen by a distant observer that ages slower. The situations are mathematically equivalent, yet you are insisting on defining your terms in such a way as to get an apparent contradiction.
See the attached image below. This is the crux of the issue I have with reciprocity.
The image shows in red, two clocks separated by some distance, (x2 - x1).
The clocks are at rest relative to each other and were synchronized in the past.
As long as nothing changes, (t = t' = Now) at both locations.
All of these statements are only true in one, ultimately arbitrary frame.
How can there be more than one true "now"? One is true, the rest are illusions.
At any moment, an impulse is imparted to the clock at x2, causing it to move away from x1 at a constant velocity. These are the blue lines.
From your previous statements, you believe that after this impulse the situation is reciprocal. I say reciprocity in this situation is an illusion. It is not reciprocal because only the clock at x2 received an impulse.
And how would an observer coming in later know that that was the case and not that they had both started moving and the first clock had been slowed to a stop? Or if the observer who looks later happens to be moving with the same speed as the second clock, it is the first clock that they would see as moving and slowed.
After receiving the impulse, in the rest frame of the clock that started at x2. Looking behind it, it's x' axis (blue) which represents "Now" is directed into the past of the clock at x1. The longer the distance (x2 - x1), the farther into the past the axis extends. I say this is an illusion because the clock (and ruler) which started at x2 has been changed by the impulse it received. The clock at x1 didn't change and the impulse didn't suddenly give us access to the past, if and when FTL is possible.
Except there is nothing different between the 2 clocks, everything is exactly identical, and all of your conclusions are based on picking a preferred frame,...
No, from a QM perspective, the clock that received the impulse was Doppler shifted into a higher energy ZP spectrum, i.e, a higher energy state wrt the vacuum ZP field. They are not exactly identical anymore at the QM scale or gravitationally. An observer coming in would not know this so an experiment would have to be conducted carefully, as was the Hafele-Keating experiment. The Lorentz transformations make the assumption that they are identical, it's built into the derivation but nobody has tested it!
but if you pick a preferred frame, you will no longer see the speed of light as constant in all frames.
This is a false assumption. As in the PV Model, everyone sees the same value c "locally". Time dilation and length contraction at higher energy states relative to the vacuum, assure that the rulers and clocks are scaled to always give "c" as the local value. It's NOT an aether.
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Except energy is frame dependent.
All energy gravitates. In that sense, it cannot be frame dependent when in a gravitational field because one clock/twin has the extra kinetic energy imparted to it and the other does not. Their gravitational attraction to the center of gravity will be different. Therefore, KE is not frame dependent when considering the gravitational effects of that energy. Time dilation is a gravitational effect based on the absolute energy content wrt the vacuum ZP energy, i.e., the gravitational field.
Moving objects have more energy, and therefore gravitate more, but the gravitational field is not simply a moving Schwarzchild solution with increased mass. Because of this, there is no contradiction between kinetic energy being different in different frames, and in fact it would not work if kinetic energy did not vary between frames. You still are simply ignoring the fact that general relativity has no problem looking at things from the perspective of a distant observer that is moving relative to the mass. This frame is still equally valid.
How can there be more than one true "now"? One is true, the rest are illusions.
I am not sure how you can ask that question. It is answered in every single book that discusses introductory relativity. The short version is that the concept of "one true now" does not make any sense given that spacelike separated events by definition cannot be put into a chronological order that everyone agrees on.
Except there is nothing different between the 2 clocks, everything is exactly identical, and all of your conclusions are based on picking a preferred frame,...
No, from a QM perspective, the clock that received the impulse was Doppler shifted into a higher energy ZP spectrum, i.e, a higher energy state wrt the vacuum ZP field. They are not exactly identical anymore at the QM scale or gravitationally.
What you are saying is that the quantum vacuum defines a universal rest frame, so as I said, you are just defining a preferred frame. This means that you should be able to measure your velocity relative to it. How would you do so? (And no, Hafele-Keating does not show a difference, you are going to state exactly what you are going to measure, and how 2 observers, one that comes in and is moving at the same velocity as clock 1 and one moving the same as clock 2, would agree on which clock was accelerated.)
An observer coming in would not know this so an experiment would have to be conducted carefully, as was the Hafele-Keating experiment. The Lorentz transformations make the assumption that they are identical, it's built into the derivation but nobody has tested it!
Except you just named a test of it. That experiment showed that relativity with its built in reciprocity makes the correct predictions. The M-M experiment clearly demonstrates that the speed of light is invariant between reference frames demonstrating that there is no difference between frames based on their velocity, which requires reciprocity to work.
You continue to claim that this has not been tested when you have been given evidence, and every counterargument you have made I have shown to be either contradictory or irrelevant. You continuing to claim this is simply ignoring everything I have written so far.
but if you pick a preferred frame, you will no longer see the speed of light as constant in all frames.
This is a false assumption. As in the PV Model, everyone sees the same value c "locally". Time dilation and length contraction at higher energy states relative to the vacuum, assure that the rulers and clocks are scaled to always give "c" as the local value. It's NOT an aether.
It is a preferred frame, you are claiming that the velocity measured relative to the vacuum matters. If that is true, then there must be a measurable difference based on this. This would be counter to the most fundamental principles that relativity is derived from, so you would simply not get the same results.
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I do not know of any reason why 2 clocks at rest and separated by a distance (x2 - x1) can't be synchronized by exchanging light pulses.
What you are saying is that the quantum vacuum defines a universal rest frame, so as I said, you are just defining a preferred frame. This means that you should be able to measure your velocity relative to it. How would you do so? (And no, Hafele-Keating does not show a difference, you are going to state exactly what you are going to measure, and how 2 observers, one that comes in and is moving at the same velocity as clock 1 and one moving the same as clock 2, would agree on which clock was accelerated.)
No. What "I" am saying is that the EM ZPF defines a zero baseline for the energy content of matter. Matter is in equilibrium with the vacuum it's immersed in. A different zero-point energy in the EM field results in a different equilibrium energy of the matter. As I said previously, you cannot measure velocity relative to the ZPF. The spectrum will Doppler shift and the matter will respond to this increased equilibrium energy. Its length will contract and time will dilate, such that the vacuum will look the same, regardless of the energy content of the object.
...The M-M experiment clearly demonstrates that the speed of light is invariant between reference frames demonstrating that there is no difference between frames based on their velocity, which requires reciprocity to work.
Again, the M-M experiment says nothing about reciprocity. You have not proven to me that it does. It only demonstrates that length contraction prevents it from detecting any change in the speed of light.
You continue to claim that this has not been tested when you have been given evidence and every counterargument you have made I have shown to be either contradictory or irrelevant. You continuing to claim this is simply ignoring everything I have written so far.
but if you pick a preferred frame, you will no longer see the speed of light as constant in all frames.
This is a false assumption. As in the PV Model, everyone sees the same value c "locally". Time dilation and length contraction at higher energy states relative to the vacuum, assure that the rulers and clocks are scaled to always give "c" as the local value. It's NOT an aether.
It is a preferred frame, you are claiming that the velocity measured relative to the vacuum matters. If that is true, then there must be a measurable difference based on this. This would be counter to the most fundamental principles that relativity is derived from, so you would simply not get the same results.
No, I'm not saying that, because I know you cannot measure velocity relative to the vacuum. You can, however, measure the energy state by comparing clocks and rulers.
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I do not know of any reason why 2 clocks at rest and separated by a distance (x2 - x1) can't be synchronized by exchanging light pulses.
The problem is the word "at rest" They can be at rest relative to each other, and synchronized in that frame, but in literally every other frame, they will not be synchronized.
What you are saying is that the quantum vacuum defines a universal rest frame, so as I said, you are just defining a preferred frame. This means that you should be able to measure your velocity relative to it. How would you do so? (And no, Hafele-Keating does not show a difference, you are going to state exactly what you are going to measure, and how 2 observers, one that comes in and is moving at the same velocity as clock 1 and one moving the same as clock 2, would agree on which clock was accelerated.)
No. What "I" am saying is that the EM ZPF defines a zero baseline for the energy content of matter. Matter is in equilibrium with the vacuum it's immersed in. A different zero-point energy in the EM field results in a different equilibrium energy of the matter. As I said previously, you cannot measure velocity relative to the ZPF. The spectrum will Doppler shift and the matter will respond to this increased equilibrium energy. Its length will contract and time will dilate, such that the vacuum will look the same, regardless of the energy content of the object.
If you cannot measure your velocity relative to it, then your velocity relative to it cannot determine anything about the behavior of objects, otherwise, you could use that effect to determine your velocity relative to it.
Since you cannot measure your velocity relative to it, it can't be a preferred frame, and since it is not a preferred frame, you must have the same laws of physics regardless of your velocity, which is logically equivalent to reciprocity.
...The M-M experiment clearly demonstrates that the speed of light is invariant between reference frames demonstrating that there is no difference between frames based on their velocity, which requires reciprocity to work.
Again, the M-M experiment says nothing about reciprocity. You have not proven to me that it does. It only demonstrates that length contraction prevents it from detecting any change in the speed of light.
No, you still don't understand the M-M experiment. It does not test length contraction, it shows that there is no frame with a special velocity, where the laws of physics change depending on your speed relative to that frame.
The consequence of this is reciprocity. I have already outlined this proof and I am getting tired of of you claiming that I haven't.
The outcome shows that inertial reference frames are equivalent regardless of velocity, this directly leads to the Lorentz transformations, which are inherently reciprocal. It does not matter how many times you claim otherwise, you have no supporting argument, and are just ignoring what the results say.
It is a preferred frame, you are claiming that the velocity measured relative to the vacuum matters. If that is true, then there must be a measurable difference based on this. This would be counter to the most fundamental principles that relativity is derived from, so you would simply not get the same results.
No, I'm not saying that, because I know you cannot measure velocity relative to the vacuum. You can, however, measure the energy state by comparing clocks and rulers.
But you keep claiming that reciprocity is wrong based on claiming that one moving object's velocity relative to the vacuum is different than another's.
You still haven't answered how to tell which clock is the one that accelerated, and some of your comments seem to be backtracking and agreeing with the point that you cannot tell which one is moving relative to the vacuum, but that is the definition of reciprocity being true.
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Here is an actual experiment with relativity that shows it is non symmetric. https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
Considering the Hafele–Keating experiment in a frame of reference at rest with respect to the center of the earth, a clock aboard the plane moving eastward, in the direction of the Earth's rotation, had a greater velocity (resulting in a relative time loss) than one that remained on the ground, while a clock aboard the plane moving westward, against the Earth's rotation, had a lower velocity than one on the ground.
2 aircraft flying in opposite directions on earth. Aircraft one, flying in the direction of the rotation of earth has its clock slowed the greatest. The clock on the ground is not as slow as aircraft 1 but is slower than aircraft 2. Aircraft 2's clock is the fastest as it moves the counter the earths rotation. Now take this path and reduce it to an instant in time with the two aircraft passing each other. One aircraft clock is running fast w.r.t. one plane while the other plane should see the others as slow. They quickly land and measure the smaller change in time via the shorter trip.
This appears to me to be non-symmetric. Oddly with respect to something that doesn't rotate and seems to be with respect to the earth center if this article is correct.
What is non-symmetric here isn't the speed of light. Both planes would record a light beam as moving at c but with various Doppler shifts so that isn't the issue (except for maybe the specifics of the light changing vacuum frames leading to Doppler shifts). What is non-symmetric is the passage of time as in the Minkowski_diagram. https://en.wikipedia.org/wiki/Minkowski_diagram where one persons time space axis tilts while the others does not (non-symmetric). Here we have the very non-symmetric effect which leads to one twin more rapidly ageing while the other doesn't.
Knowing what your moving with respect to is detectable by the passage of time not the speed of light. This is exactly what they detected. This is why I stated, "This appears to me to be non-symmetric. Oddly with respect to something that doesn't rotate and seems to be with respect to the earth center if this article is correct."
It is also one of the reasons I have speculated that the vacuum might be considered to flow into a gravity well such that the vacuum reaches the speed of light at an event horizon where time stops and light can't escape. Faster your moving with respect to this speculated vacuum the slower time appears to pass. There might also be something to this imaginary time as another dimension where objects become timeless or some transition between that slows time. Not really sure about the last idea.
Frame dragging is another aspect I suspect to be an example of a flow in vacuum.
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What is non-symmetric here isn't the speed of light. Both planes would record a light beam as moving at c but with various Doppler shifts so that isn't the issue (except for maybe the specifics of the light changing vacuum frames leading to Doppler shifts). What is non-symmetric is the passage of time as in the Minkowski_diagram. https://en.wikipedia.org/wiki/Minkowski_diagram where one persons time space axis tilts while the others does not (non-symmetric). Here we have the very non-symmetric effect which leads to one twin more rapidly ageing while the other doesn't.
Knowing what your moving with respect to is detectable by the passage of time not the speed of light. This is exactly what they detected. This is why I stated, "This appears to me to be non-symmetric. Oddly with respect to something that doesn't rotate and seems to be with respect to the earth center if this article is correct."
The passage of time demonstrated in a Minkowski diagram is symmetric though. The assymmetry in this experiment purely comes from the fact that all of the clocks (including the one on the ground due to earth's rotation) have a constantly changing velocity vector. This causes (for the special relativistic portion) the "bent" spatial axis, and the direction of the bend of the time axis to be constantly changing. This changing of the spatial axes is what produces the measured effects and it is possible to directly measure they are changing. This is similar to how "fictitious" forces need to be accounted for in classical physics when using a rotating reference frame. You mentioned this with the changing frames leading to Doppler shifts.
The calculations being done next to the non-rotating earth center frame are just for convenience. You could do all of the same calculations from the sun's inertial frame where all of the clocks are moving in a spiral, and you get consistent results showing that there is no need to consider the earth frame as special.
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I'll get back to what we were discussing later. Right now, let's consider Frame Dragging.
The Hafele–Keating experiment,
https://en.wikipedia.org/wiki/Hafele–Keating_experiment (https://en.wikipedia.org/wiki/Hafele–Keating_experiment)
has both Kinematic and Gravitational time dilation at work. The Kinematic time dilation stands out because;
"Considering the Hafele–Keating experiment in a frame of reference at rest with respect to the center of the earth, a clock aboard the plane moving eastward, in the direction of the Earth's rotation, had a greater velocity (resulting in a relative time loss) than one that remained on the ground, while a clock aboard the plane moving westward, against the Earth's rotation, had a lower velocity than one on the ground.[2]"
There is an alternate interpretation of this. If there were a gravitomagnetic potential, AG has units of velocity, m/s, it is essentially the cause of frame dragging. One could draw the conclusion that the field (space-time) rotates in the direction of the earth's rotation. Flying eastward, the clock is moving faster than the field, AG-v < 0. Flying westward, the clock is moving slower than the field, AG - v > 0. This would imply that there is a preferred reference frame that is "at rest" relative to the rotating field AG. They used the center of the earth as the reference, which would also be the center of the rotation, AG => 0 as the flux through the loop, ΦG => 0 at the singularity r=0.
The 3 clocks run at different rates. They are not reciprocal. The field AG provides a background velocity field relative to which they are moving.
Possible or no?
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I'll get back to what we were discussing later. Right now, let's consider Frame Dragging.
Please do get back to it, because frame dragging seems to be an additional complication that you are bringing up to try and avoid the fact that you can't consistently explain simple situations in a non-reciprocal way.
The Hafele–Keating experiment,
...
First frame dragging typically refers to rotational frame dragging from a spinning massive object. Linear frame dragging is also a thing and is a consequence of the fact that for consistency, gravity must look different from a moving frame, since gravitational influences only propagate at the speed of light, and the additional kinetic energy the object has in a frame moving relative to it increases its relativistic mass.
Rotational frame dragging is a negligible effect in the Hafele-Keating experiment.
There is an alternate interpretation of this. If there were a gravitomagnetic potential, AG has units of velocity, m/s, it is essentially the cause of frame dragging. One could draw the conclusion that the field (space-time) rotates in the direction of the earth's rotation. Flying eastward, the clock is moving faster than the field, AG-v < 0. Flying westward, the clock is moving slower than the field, AG - v > 0. This would imply that there is a preferred reference frame that is "at rest" relative to the rotating field AG. They used the center of the earth as the reference, which would also be the center of the rotation, AG => 0 as the flux through the loop, ΦG => 0 at the singularity r=0.
To reiterate, frame dragging is a measured effect, but much smaller than the results of this experiment could measure, so your explanation already fails. Even more so, your conclusion breaks down when you instead look at things from the perspective of the sun's inertial frame. This is a complicated situation to do that for, which is why a simpler example would be better, but you cannot claim non-reciprocity just because there is a frame where the calculations are easier.
The 3 clocks run at different rates. They are not reciprocal. The field AG provides a background velocity field relative to which they are moving.
Possible or no?
Referring to the field of the object to define a special frame is like referring to the rest frame of a charged object as special because you don't have to calculate the magnetic field. The fact is that physics has forces that are a function of the relative velocity between 2 objects, but the underlying physics does not define any kind of "absolute" velocity.
No, they are reciprocal (at least for the portion that doesn't depend on depth in a gravitational well). Asymmetries arise from the fact that they are accelerated differently as their directions change relative to each other, but the same math that correctly calculates how much time delta changes between them also requires that changing your mind halfway through the trip on what path you are taking, or by moving the "stationary" clock would change the results. A theory that claims that there is an absolute measure at all times of which clock is slower or faster would simply produce different results.
Rather than sort this out for a complicated experiment with multiple overlapping effects, wouldn't it be easier to go back to the simple example we were talking about with separated clocks?
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I will refer to this paper here http://www.cellularuniverse.org/R2SpeedParadox.pdf (How DSSU Relativity Resolves the Speed Paradox Measurable Absolute Motion Resolves a Paradox in Einstein’s Special Relativity by Conrad Ranzan)
It seems to also predict a variable non-local speed of light will locally making it measurably invariable. I think it mentions the effect of the vacuum on the local ruler, the twin paradox and asymmetry in time travel.
Below they touch on the vacuum flow being related to gravity ( http://cellularuniverse.org/Th6EnergyProcess-Part1_Ranzan.pdf )
The DSSU gravitational field is fundamentally
different. Instead of a force field it is a dynamic aether
“field” —an active region which can be divided into two
functional components.
The first is the aether flow field. Surrounding any
gravitating body there is a bulk flow of aether —a
continuous streaming into the central mass body. The
speed of the aether flow increases with proximity to the
surface of the central body.
A book with a short explanation of DSSU or Dynamic Steady State Universe
Google books Astronomy, Cosmology and Fundamental Physics: Proceedings of the ESO/CERN ... (https://books.google.com/books?id=cbGOp8NXMO0C&pg=PA475&lpg=PA475&dq=dssu+steady+state+universe&source=bl&ots=LrcCQJ8_0V&sig=9CTJGXeJ2V4ONr1joHqoBM7rlwg&hl=en&sa=X&ved=0ahUKEwjPs7HPgoHYAhUF5yYKHWhTDBsQ6AEIYjAN#v=onepage&q=dssu%20steady%20state%20universe&f=false)
I am not endorsing it just that it is interesting. Pondering if it holds out in all circumstances. Havn't really found any papers contradicting it yet. A paper in favor it seems here: Google shcholar A Strange Detail
Concerning the Conceptualization of the
Hubble Constant (https://scholar.google.com/scholar?cluster=739763563447511513&hl=en&as_sdt=0,26&sciodt=0,26)
Edit: some more I found later, (another article I have yet to find also - never found it something about the quantum vacuum falling in a gravity well.)
Of course, the most striking aspect of the above
equation is that <rho> is negative. It is therefore interesting
to understand the origin of the minus sign in more details
...
where ... are the particle
and anti-particle number operators respectively. Of
course, their mean value vanishes in the vacuum state
which contains no particle. The zero point energy is thus
given by the formally infinite term δ(0). Since this term
appears with a minus sign in the Hamiltonian, the corresponding
energy density is indeed negative. The origin of
this minus sign is the anti-commuting properties of the
creation and annihilation operators. We conclude that
the vacuum energy density is negative because we deal
with fermions which are anti-commuting objects.
...
we estimate the vacuum energy and find a value
very far from the often quoted “122 orders of magnitude”.
...
4. Schr¨odinger Equation in an Accelerated Frame
It is also frequent to refer to the weak equivalence principle
as the property stating that, locally, the effect of a
constant gravitational field can be mimicked by an accelerating
frame. Therefore, it is interesting to study
whether this claim holds in quantum mechanics. This
question has been studied in Refs. [146, 150, 151]. Here,
we follow the treatment of Ref. [146].
Let us consider the free Schr¨ondinger equation (in one
dimension to simplify the problem).
...
we find that the equivalence between a constant
gravitational field and an accelerated frame propagates
to quantum mechanics.
https://arxiv.org/pdf/0705.2611.pdf (How does Casimir energy fall? II. Gravitational acceleration of quantum vacuum energy Kimball A. Milton,∗ Prachi Parashar,† K. V. Shajesh,‡ and Jef Wagner§)
https://arxiv.org/pdf/cond-mat/9711071.pdf (The ‘Friction’ of Vacuum, and other Fluctuation–Induced Forces
Mehran Kardar , Ramin Golestanian)
In a previous paper we have shown it is possible to build alternative versions of Special Theory of Relativity only considering homogeneity of space, of time and Relative Principle without invoking the postulate of invariance of light velocity in all the inertial frames. Within these alternatives, space and time transformations different than the Lorentz ones like, in particular, the Selleri inertial transformations, are possible. This has many important consequences as, for example, the need for the distinction between physical time as duration of change in space and mathematical time as a parameter quantifying this change as well as the anisotropy of one-way velocity of light. ...
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A test I believe might indicate a relative velocity with respect to such a frame would be to measure the static dipole electric field of a magnetic field. In the lab frame. If there is no difference in clock rates for the individual charges in the lab frame no dipole electric field should form in the lab frame.
However if for some reason the clock of a charge sped up moving in some particular direction in the lab, as opposed to another direction, there should be a corresponding dipole electric field to go with it.
Such an experiment with sufficient sensitivity, I believe could determine velocity relative to a local field that determines the clock rate.
I suspect existing in a gravity field may induce some effect but I would be curious of it's exact orientation of the lab frame dipole electric field. Parallel or perpendicular to Earth's surface.
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Getting back to it...
There are two identical clocks, at rest wrt each other and synchronized at the same place, at the same time.
My hypothesis is; that if you accelerate either one of these clocks, "work" is performed on that clock that is not performed on the other clock. It is the work performed that makes that clock run "slower" because it now has a higher energy content, its Tuv has changed. The situation is not symmetrical, since no work was done to the other clock. It's rate isn't affected and it's energy-momentum tensor is unchanged.
However, given the previous example where one of the clocks was put into orbit at the same altitude as the other clock. Work was done to the clock in orbit, and now it is in free-fall, where there are no forces and no proper acceleration in the frame of the orbiting clock. The clock in orbit runs slower than the clock that is hovering at the same altitude. Even though the hovering clock feels a force supporting it, no work has been done to it because it hasn't moved anywhere. In this scenario, the clocks do not tick at the same rate, their Tuv's are different, AND observers with each clock will agree on whose clock is running faster or slower. It is not reciprocal.
This non-reciprocity cannot be demonstrated with Lorentz transformations because they are inherently reciprocal. The fact that the observer and the source are moving toward or away from each other changes the situation, such that the changing time delay between them gives the "illusion" of reciprocity. I say it is an illusion because it is not present in the orbital scenario where it can be tested. The issue is that the differences in the Tuv of each clock is ignored, because the work done is not taken into consideration.
Are we clear up to this point?
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Getting back to it...
There are two identical clocks, at rest wrt each other and synchronized at the same place, at the same time.
My hypothesis is; that if you accelerate either one of these clocks, "work" is performed on that clock that is not performed on the other clock. It is the work performed that makes that clock run "slower" because it now has a higher energy content, its Tuv has changed. The situation is not symmetrical, since no work was done to the other clock. It's rate isn't affected and it's energy-momentum tensor is unchanged.
How does some observer passing by (moving at some arbitrary velocity) know which clock was accelerated? Your hypothesis is meaningless if you cannot answer this question. If the answer is "they can't" then you are left with a perfectly symmetrical situation.
However, given the previous example where one of the clocks was put into orbit at the same altitude as the other clock. Work was done to the clock in orbit, and now it is in free-fall, where there are no forces and no proper acceleration in the frame of the orbiting clock. The clock in orbit runs slower than the clock that is hovering at the same altitude. Even though the hovering clock feels a force supporting it, no work has been done to it because it hasn't moved anywhere. In this scenario, the clocks do not tick at the same rate, their Tuv's are different, AND observers with each clock will agree on whose clock is running faster or slower. It is not reciprocal.
We already had this conversation, and your description here does nothing to change what I already said:
I'm glad we agree. :) However, the situation is not the same as what you describe. Flying in a big circle requires forces acting on the ship/twin for the whole trip. This is equivalent to the twin hovering in my experiment. In your situation, the other twin at rest would age faster. In the situation which I described we have the opposite. It is the twin in the inertial frame in free fall that ages slower and the one accelerating (forces present) that ages faster.
In both situations it is the twin that is moving in a circle as seen by a distant observer that ages slower. The situations are mathematically equivalent, yet you are insisting on defining your terms in such a way as to get an apparent contradiction.
The key is that the one with the slow clock is experiencing a constantly changing metric.
This non-reciprocity cannot be demonstrated with Lorentz transformations because they are inherently reciprocal. The fact that the observer and the source are moving toward or away from each other changes the situation, such that the changing time delay between them gives the "illusion" of reciprocity. I say it is an illusion because it is not present in the orbital scenario where it can be tested. The issue is that the differences in the Tuv of each clock is ignored, because the work done is not taken into consideration.
You also cannot consistently describe simple situations without the Lorentz transformations. No matter how many times you call it an "illusion" the fact is that you need to accept reciprocity to come to a consistent conclusion regarding the "twin paradox" and similar situations. Your "work done" hypothesis still makes no sense, because how do you know they didn't both start in orbit, and the work was done on the one that ends up hovering. You are also still simply ignoring the perspective of a distant observer that is moving at a constant velocity relative to the central mass.
Are we clear up to this point?
The only thing clear at this point is that you are determined to ignore everything I say, and have not answered a single one of my questions.
Despite starting your post with "getting back to it," you did nothing in this post to address the post you had previously said that you would get back to which ended with the following question to you:
You still haven't answered how to tell which clock is the one that accelerated, and some of your comments seem to be backtracking and agreeing with the point that you cannot tell which one is moving relative to the vacuum, but that is the definition of reciprocity being true.
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Getting back to it...
There are two identical clocks, at rest wrt each other and synchronized at the same place, at the same time.
My hypothesis is; that if you accelerate either one of these clocks, "work" is performed on that clock that is not performed on the other clock. It is the work performed that makes that clock run "slower" because it now has a higher energy content, its Tuv has changed. The situation is not symmetrical, since no work was done to the other clock. It's rate isn't affected and it's energy-momentum tensor is unchanged.
How does some observer passing by (moving at some arbitrary velocity) know which clock was accelerated? Your hypothesis is meaningless if you cannot answer this question. If the answer is "they can't" then you are left with a perfectly symmetrical situation.
Simple! The random "inertial" observer passing by, would need to use his sensors (telescope) to read the face of both clocks as the two clocks pass each other. He would need to observe 1 or more complete orbits (2 readings) to acquire the data to compare the time elapsed on each clock. The one that is running slower is the one that was accelerated in the past. He doesn't need to assume anything, and his velocity is irrelevant when doing the comparison, because he is not comparing to his own clock.
Also, if both clocks were synchronized while in orbit, work had to be done to both clocks to get them there in the first place, the work increased the energy content of both clocks. Therefore, work must also be done to restore it to its hovering platform, but this work is in the opposite direction and therefore removes the energy that was previously given to it when it was put into orbit. In other words, this work lowers its energy content by removing what was previously added. No one would argue the fact that the clock in orbit has a higher kinetic energy than the one on the platform.
Work done in the past is part of the system as a whole, it can't be ignored. There is no such thing as a reference frame where the clocks are in orbit but have "never" been accelerated to get to that frame of reference at some time in the past.
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Getting back to it...
There are two identical clocks, at rest wrt each other and synchronized at the same place, at the same time.
My hypothesis is; that if you accelerate either one of these clocks, "work" is performed on that clock that is not performed on the other clock. It is the work performed that makes that clock run "slower" because it now has a higher energy content, its Tuv has changed. The situation is not symmetrical, since no work was done to the other clock. It's rate isn't affected and it's energy-momentum tensor is unchanged.
How does some observer passing by (moving at some arbitrary velocity) know which clock was accelerated? Your hypothesis is meaningless if you cannot answer this question. If the answer is "they can't" then you are left with a perfectly symmetrical situation.
Simple! The random "inertial" observer passing by, would need to use his sensors (telescope) to read the face of both clocks as the two clocks pass each other. He would need to observe 1 or more complete orbits
What orbits? Nothing is orbiting anything in the described situation.
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Getting back to it...
There are two identical clocks, at rest wrt each other and synchronized at the same place, at the same time.
My hypothesis is; that if you accelerate either one of these clocks, "work" is performed on that clock that is not performed on the other clock. It is the work performed that makes that clock run "slower" because it now has a higher energy content, its Tuv has changed. The situation is not symmetrical, since no work was done to the other clock. It's rate isn't affected and it's energy-momentum tensor is unchanged.
How does some observer passing by (moving at some arbitrary velocity) know which clock was accelerated? Your hypothesis is meaningless if you cannot answer this question. If the answer is "they can't" then you are left with a perfectly symmetrical situation.
Simple! The random "inertial" observer passing by, would need to use his sensors (telescope) to read the face of both clocks as the two clocks pass each other. He would need to observe 1 or more complete orbits
What orbits? Nothing is orbiting anything in the described situation.
I thought we were getting back to my previous example, where one clock is in free fall (orbit) and the other is hovering on a platform. That's where I'm at.
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What orbits? Nothing is orbiting anything in the described situation.
I thought we were getting back to my previous example, where one clock is in free fall (orbit) and the other is hovering on a platform. That's where I'm at.
The quoted section of your post did not mention orbiting. The post of mine that you previously said that you would get back to and I quoted/linked at the end of my previous post was This post. (https://forum.nasaspaceflight.com/index.php?topic=43385.msg1755397#msg1755397) We were not discussing anything orbiting there either.
For convenience, that example started with your image here (https://forum.nasaspaceflight.com/index.php?topic=43385.msg1755245#msg1755245) which discusses 2 clocks in free space with no description of being in orbit of anything. Also, I don't care if you had meant to imply them being in orbit of something, but never said so for multiple posts in a row. What we need to discuss right now is clocks in free space with no nearby gravity wells.
You keep using objects being in orbit to add confusion by ignoring the difference between moving in a circle/helix and moving in a straight line, misusing the equivalence principle, and creating the illusion of a preferred frame, since there is one frame that is much easier to do calculations in. The inherent contradictions in your claims will be much more obvious if we stop talking about orbits for now.
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Are there any example of real experiments being performed in deep space away from gravity wells? Some deep space probes not moving in circular orbits. It seems nature conspires in a rotating frame to give the illusion of absolute motion but we need a test of non rotating frames in deep space. Wonder if some of the probe anomalies could be connected.
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Except energy is frame dependent. In a frame based on a distant observer that is moving at the same instantaneous velocity as the orbiting twin, the orbiting twin is the one with less (0) kinetic energy. Your claim of "no reciprocity" ignores the existence of this frame.
For me, it comes down to this quote "energy is frame dependent". Obviously, in an orbital situation, the kinetic energy makes a big difference. A clock that has it, stays in orbit. A clock that doesn't, falls to the ground. This perspective comes from choosing the center of mass frame.
If you eliminate the center of mass frame, I have no solution. On the other hand, there is nowhere in our entire galaxy that is not relative to some center of mass object. Be it the earth, the sun or Sagittarius A. So what is the point of discussing a situation where there is no gravitational potential as is done in SR? There is nowhere in our galaxy where it would apply, except as an approximation to a larger model. I can choose any center of mass I want, but it have to have a center of mass relative to which, a gravitational potential can be established in order to know the rate at which clocks "actually" tick. Not the rate they are perceived to tick by a moving observer.
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Except energy is frame dependent. In a frame based on a distant observer that is moving at the same instantaneous velocity as the orbiting twin, the orbiting twin is the one with less (0) kinetic energy. Your claim of "no reciprocity" ignores the existence of this frame.
For me, it comes down to this quote "energy is frame dependent". Obviously, in an orbital situation, the kinetic energy makes a big difference. A clock that has it, stays in orbit. A clock that doesn't, falls to the ground. This perspective comes from choosing the center of mass frame.
I have said this repeatedly, yet you still have not acknowledged it:
You can pick a frame where the large mass is moving, then you can do so in a way that the "hovering" object has more kinetic energy than the orbiting one (at least some of the time)
If you eliminate the center of mass frame, I have no solution.
The universe does not have a center of mass frame. As far as we know, the universe may contain an infinite amount of mass across an infinite amount of space. I don't have to remove a frame that doesn't exist in reality.
On the other hand, there is nowhere in our entire galaxy that is not relative to some center of mass object. Be it the earth, the sun or Sagittarius A. So what is the point of discussing a situation where there is no gravitational potential as is done in SR?
There are countless situations where gravitational potentials are irrelevant and space is essentially flat. You can imagine a couple of clocks halfway between here alpha centuari, and you would be able to have them move around at relativistic speeds for a few light weeks in any direction without having to worry about any gravity wells, and motion relative to the center of the galaxy would be negligible on that scale, so any effects from changing gravitational potential or such would be negligible.
There is nowhere in our galaxy where it would apply, except as an approximation to a larger model.
As I said, for all meaningful purposes there are such places, and general relativity says that you get special relativity in them. You are the one missing the big picture, because if your model does not reduce to this in these cases, then your model is simply inconsistent. If your model was consistent, then you would have no problem answering what happens in the simplest cases.
I can choose any center of mass I want, but it have to have a center of mass relative to which, a gravitational potential can be established in order to know the rate at which clocks "actually" tick. Not the rate they are perceived to tick by a moving observer.
Except, your model is now dependent on the choice of center of mass (earth, sun, center of galaxy, etc.) so it gives different results for each situation and is inconsistent.
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Except energy is frame dependent. In a frame based on a distant observer that is moving at the same instantaneous velocity as the orbiting twin, the orbiting twin is the one with less (0) kinetic energy. Your claim of "no reciprocity" ignores the existence of this frame.
For me, it comes down to this quote "energy is frame dependent". Obviously, in an orbital situation, the kinetic energy makes a big difference. A clock that has it, stays in orbit. A clock that doesn't, falls to the ground. This perspective comes from choosing the center of mass frame.
I have said this repeatedly, yet you still have not acknowledged it:
You can pick a frame where the large mass is moving, then you can do so in a way that the "hovering" object has more kinetic energy than the orbiting one (at least some of the time)
You could, but it would be wrong to do so. The resulting frame would not be an inertial frame, it would have forces acting on the observer at all times.
If you eliminate the center of mass frame, I have no solution.
The universe does not have a center of mass frame. As far as we know, the universe may contain an infinite amount of mass across an infinite amount of space. I don't have to remove a frame that doesn't exist in reality.
I couldn't care less about the rest of the universe. Our galaxy is big enough to explore for the next few millennia, at least! Sagittarius-A would be the center of mass until we are half-way to Andromeda. The space between the Sun and Alpha Centauri still has a gravitational potential relative to the Sag-A that can be used to set the baseline for the rate at which a clock will tick. It is also there to set the baseline to compare which clock has a kinetic energy content and which does not, relative to this CM. From that, the difference in the rate of the two clocks can be determined.
On the other hand, there is nowhere in our entire galaxy that is not relative to some center of mass object. Be it the earth, the sun or Sagittarius A. So what is the point of discussing a situation where there is no gravitational potential as is done in SR?
There are countless situations where gravitational potentials are irrelevant and space is essentially flat. You can imagine a couple of clocks halfway between here alpha centuari, and you would be able to have them move around at relativistic speeds for a few light weeks in any direction without having to worry about any gravity wells, and motion relative to the center of the galaxy would be negligible on that scale, so any effects from changing gravitational potential or such would be negligible.
The gravitational potential is only irrelevant if you don't care about comparing the rate at which clocks tick. If that is the goal, then gravity can't be ignored anywhere in the Universe.
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You could, but it would be wrong to do so. The resulting frame would not be an inertial frame, it would have forces acting on the observer at all times.
The frame of a distant observer moving at constant speed is an inertial frame.
I couldn't care less about the rest of the universe.
If your theory is inconsistent anywhere in the universe then it is wrong.
The space between the Sun and Alpha Centauri still has a gravitational potential relative to the Sag-A that can be used to set the baseline for the rate at which a clock will tick. It is also there to set the baseline to compare which clock has a kinetic energy content and which does not, relative to this CM. From that, the difference in the rate of the two clocks can be determined.
So at some point when leaving the solar system, the Voyager clocks will suddenly start ticking slower because the center of mass frame changed? Either there is one and only one rest frame for the whole universe that determines this, or there is no universal rest frame and all frames are equally valid, no jumping to only "center of mass" frames. You can't have it both ways, and experimental data supports the second one.
There are countless situations where gravitational potentials are irrelevant and space is essentially flat. You can imagine a couple of clocks halfway between here alpha centuari, and you would be able to have them move around at relativistic speeds for a few light weeks in any direction without having to worry about any gravity wells, and motion relative to the center of the galaxy would be negligible on that scale, so any effects from changing gravitational potential or such would be negligible.
The gravitational potential is only irrelevant if you don't care about comparing the rate at which clocks tick. If that is the goal, then gravity can't be ignored anywhere in the Universe.
For the described situations, the gravitational potential would be essentially constant, therefore it has the same effect on all of the clocks. You can't talk about orbits when the scenario is measured in weeks and the orbit is similar to the sun's around Sagittarius-A.
Now are you going to attempt to answer the question of how to tell apart 2 clocks at the same gravitational potential that are moving relative to each other or are you going to keep making excuses and avoiding the question?
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The gravitational potential is only irrelevant if you don't care about comparing the rate at which clocks tick. If that is the goal, then gravity can't be ignored anywhere in the Universe.
For the described situations, the gravitational potential would be essentially constant, therefore it has the same effect on all of the clocks. You can't talk about orbits when the scenario is measured in weeks and the orbit is similar to the sun's around Sagittarius-A.
Now are you going to attempt to answer the question of how to tell apart 2 clocks at the same gravitational potential that are moving relative to each other or are you going to keep making excuses and avoiding the question?
Constant or not, the gravitational potential sets the baseline for the rate at which the clock ticks. That gravitational potential has a source, assumed to be at the center of mass of whatever field(s) created that potential. Kinetic energy must be measured relative to that, regardless of where in the universe the clock is located.
In regards to your question, here is the procedure:
The observer who comes onto the scene where there are 2 clocks in motion relative to each other, and relative to him.
1. He must first determine where is the center of gravity for region of space, and then adjust his position and speed to match that frame.
2. Then measure the rate of each clock by comparing their rates and kinetic energy, in this frame.
It doesn't have to be a universal rest frame. It only has to be a gravitational field from which to derive a baseline. The spectral energy density of the vacuum is free to be different from place to place in space-time, and any matter will conform (scale) itself to establish equilibrium with that local density. That kinda makes it difficult to measure!
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Constant or not, the gravitational potential sets the baseline for the rate at which the clock ticks. That gravitational potential has a source, assumed to be at the center of mass of whatever field(s) created that potential. Kinetic energy must be measured relative to that, regardless of where in the universe the clock is located.
Your assumption is bad. There can be multiple sources, distributed sources, and sources moving with varying velocities relative to each other.
And effectively constant potential does matter, because the apparent rate of clocks ticking depends on the velocity as well. If you ignore this, then you can't explain constancy of speed of light regardless of the velocity of a frame.
In regards to your question, here is the procedure:
The observer who comes onto the scene where there are 2 clocks in motion relative to each other, and relative to him.
1. He must first determine where is the center of gravity for region of space, and then adjust his position and speed to match that frame.
This step makes no sense, how do you define this frame, what if the field comes from 2 equal masses equally far away in different directions, moving at different speeds? Note that the fact that they are moving at different speeds, means that you can pick frames where you are closer to one or the other. To give you a start on this, the fields are determined by the retarded position of the masses rather than the current position, because gravity propagates at the speed of light (although you have to take into account the velocity dependent effects. In Electromagnetism this results in the E-field pointing towards the current location of a moving charge rather than the retarded position.)
2. Then measure the rate of each clock by comparing their rates and kinetic energy, in this frame.
So in the end of the day you are just picking a preferred frame despite the fact that the Michelson Morley experiment and related tests says that there is no preferred frame.
Some thought experiments for you to work through, in all cases start with the clocks some distance apart and moving directly away from each other, assume they were synchronized when they were next to each other. Have one be initially at rest in your preferred frame.
1. Give the moving clock a delta-v equal to 2*v (where v is its initial velocity) to bring them back together.
2. Give the stationary clock a delta-v of 2*v/(1+v^2/c^2) to bring them back together. (slightly less velocity change in your "special" frame due to the same change in momentum having less change in velocity as the object speed approaches c.
If for both cases 1 and 2 it is the clock that you gave the delta-v to that is slowed, (and by the same amount in both cases) then it is clear that this is a reciprocal situation, and your special frame has nothing special about it. If you get a different answer than this, then if you explain what you did I will be able to find a contradiction either within your procedure or between your procedure and experiment.
It doesn't have to be a universal rest frame. It only has to be a gravitational field from which to derive a baseline. The spectral energy density of the vacuum is free to be different from place to place in space-time, and any matter will conform (scale) itself to establish equilibrium with that local density. That kinda makes it difficult to measure!
If it is not a universal frame, then observers in the different frames will still disagree on which clock is slowed, and you do not have the universal time that you keep claiming.
It is not just difficult to measure, but you have failed to actually define how to measure it. Your method here was to "determine the center of gravity" which is both an undefined concept and an undefined method. You don't actually use the clocks for the main determination. This undercuts your point, because if one is absolutely right and not the other, their must be a way to measure that. If there isn't, you are just back to relativity where both are "right" because their is no special frame.
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This seems connected to the discussion.
Dark energy: the absolute electric potential of the universe (https://scholar.google.com/scholar?cluster=14316484468462525720&hl=en&as_sdt=0,26)
In this essay we will discuss one of the most striking consequences of
electromagnetism in the cosmological context, which is the possibility that
the universe at large scales not only sets a privileged reference frame, but
could also determine an absolute electric potential. Indeed, it is well known
that the presence of matter and radiation in the universe implies that, on
large scales, the universe as a whole has associated a privileged reference
frame. That frame is nothing but the cosmic center of mass frame [2] of the
different components (baryonic and dark matter, radiation and dark energy).
In the case in which all such components are at rest with respect to each
other, the frame can be identified with that of the observers who see an
isotropic cosmic microwave background.
...
Does it make sense
to talk about a privileged electromagnetic gauge? We will argue that dark
energy, responsible for the accelerated expansion of the universe, could be
nothing but the energy density associated to such absolute electric potential
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Given two clocks at rest wrt each other, in empty space.
Scenario 1)
1. Give clock 1 a kick to provide kinetic energy. It's energy has been increased, therefore this clock is now running slower than clock 2. The two clocks now have a relative velocity of v.
2. Give clock 1 a reverse kick to stop it's motion, v=0. Now, both clocks tick at the same rate.
3. Give clock 1 another reverse kick to bring it back to clock 1. The two clocks now have a relative velocity -v. Clock 1 is ticking slower than clock 2 again.
4. Give clock 1 another kick to stop its motion when it arrives at clock 2. v=0. You will find that clock 1 ticked off less time than clock 2, because it spent most of the time in a higher energy state.
Scenario 2)
1. Give clock 1 a kick to provide kinetic energy. It's energy has been increased, therefore this clock is now running slower than clock 2. The two clocks now have a relative velocity of v.
2. Give clock 2 the same kick towards clock 1. Their relative motion ceases, v=0. Both clocks tick at the same rate, but slower than their original rate.
3. Give clock 2 another kick towards clock 1. The two clocks now have a relative velocity -v. Clock 2 is now ticking slower than clock 1.
4. Give clock 2 a reverse kick to stop its motion relative to clock 1, when it arrives at clock 1. v=0. You will find that clock 1 has ticked off more time than clock 2, because clock 2 spent more time in a higher energy state.
5. At the end of this scenario, both clocks are ticking slower than they were at the end of the first scenario above.
Energy in SR may appear to be frame dependent, or observer dependent. But in fact the kinetic energy is a real quantity that had to be given to, or taken away from one clock or the other.
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Given two clocks at rest wrt each other, in empty space.
...
Those are correct and accurate descriptions of what you see from the initial rest frame. If you start just after step 1, and use the clock 1's frame while it is moving at v relative to clock 2 the exact same descriptions work, just flipping which is scenario 1 or 2. There is therefore nothing special about the first frame, and things are perfectly reciprocal, unless you are claiming that the numeric value of the observed time delta when the clocks meet back up is not the same in the 2 situations, in which case you need to repeat this description using numbers and math.
Energy in SR may appear to be frame dependent, or observer dependent. But in fact the kinetic energy is a real quantity that had to be given to, or taken away from one clock or the other.
Except for the fact that it is frame dependent and your descriptions illustrate this. The 2 situations are exact mirrors of each other. Scenario 2 is the exact description of scenario 1 if you come in just after the first step, and pick the clock that gets the kicks in the middle as your frame of reference, because as far as you know it was the other clock that got the initial kick.
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Given two clocks at rest wrt each other, in empty space.
...
Those are correct and accurate descriptions of what you see from the initial rest frame. If you start just after step 1, and use the clock 1's frame while it is moving at v relative to clock 2 the exact same descriptions work, just flipping which is scenario 1 or 2. There is therefore nothing special about the first frame, and things are perfectly reciprocal, unless you are claiming that the numeric value of the observed time delta when the clocks meet back up is not the same in the 2 situations, in which case you need to repeat this description using numbers and math.
Energy in SR may appear to be frame dependent, or observer dependent. But in fact the kinetic energy is a real quantity that had to be given to, or taken away from one clock or the other.
Except for the fact that it is frame dependent and your descriptions illustrate this. The 2 situations are exact mirrors of each other. Scenario 2 is the exact description of scenario 1 if you come in just after the first step, and pick the clock that gets the kicks in the middle as your frame of reference, because as far as you know it was the other clock that got the initial kick.
They are not exact mirrors because, in Scenario 1 the two clocks end with the same rate they started with. In Scenario 2 the two clocks end while running at a slower rate then they were at when they started. The end of the experiment is NOT the same.
IMO, such a scenario that skips step 1 is not a well defined problem, therefore the answers will be ambiguous. That is where you make an assumption that it doesn't matter. The rate of the clocks at the end of each scenario are different, therefore the two scenarios are not the same and step 1 does matter.
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They are not exact mirrors because, in Scenario 1 the two clocks end with the same rate they started with. In Scenario 2 the two clocks end while running at a slower rate then they were at when they started. The end of the experiment is NOT the same.
Except there is NO way to tell that they are different. If you execute scenario 2, but use the frame of clock 1(after the unnecessary step 1) then clock 1 will be ticking at a constant rate the entire time, and both clocks end up ticking at that same rate at the end, with clock 2 being slow during all the times that it is moving. This is EXACTLY scenario 1.
IMO, such a scenario that skips step 1 is not a well defined problem, therefore the answers will be ambiguous.
That is not an opinion, that is a factually incorrect statement. The answers aren't ambiguous, because you get the same result either way. The only thing that is not well defined is how you determine this special rest frame you claim everything has to start from.
That is where you make an assumption that it doesn't matter. The rate of the clocks at the end of each scenario are different, therefore the two scenarios are not the same and step 1 does matter.
I am not making an assumption that it doesn't matter, but demonstrating that you get the exact same conclusion from either frame. It is the conclusion, and was not assumed, just tested to see if it was true.
You are the one that is making the assumption that they both have to start at the same velocity and there is something special about that initial velocity. You have not demonstrated anything special about that velocity though.
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They are not exact mirrors because, in Scenario 1 the two clocks end with the same rate they started with. In Scenario 2 the two clocks end while running at a slower rate then they were at when they started. The end of the experiment is NOT the same.
Except there is NO way to tell that they are different.
....
Add a 3rd clock to step 1 whose energy is never changed by any kicks and it remains in the initial rest frame. Then at the end of Scenario 2, the two clocks that are in motion will be running slower than the 3rd clock. Whereas, at the end of Scenario 1, they are all three running at the same rate, but have elapsed different times during the experiment. See the difference?
They all agree at the end of both experiments, that the 3rd clock that didn't move elapsed the most time.
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Add a 3rd clock to step 1 whose energy is never changed by any kicks and it remains in the initial rest frame. Then at the end of Scenario 2, the two clocks that are in motion will be running slower than the 3rd clock. Whereas, at the end of Scenario 1, they are all three running at the same rate, but have elapsed different times during the experiment. See the difference?
No, because, you can just have the third clock already moving with speed v instead. Your choice of relative speed for the third clock is arbitrary, and has no effect on anything. It is equivalent to picking the frame you are working in, having the clock moving at speed v to start with is what I did when I said "use the frame of clock 1(after the unnecessary step 1)" Everything therefore still remains unchanged.
They all agree at the end of both experiments, that the 3rd clock that didn't move elapsed the most time.
No, when clocks are spatially separated, there can be no agreement on the relative reading of the clocks, you would have to extend the scenario to bring the clocks together to make this statement, and the answer would depend on which clocks you accelerate in the process.
Did you actually read the rest of my post? Because you are still using the unjustified assumption that the clocks start in a special rest frame.
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Did you actually read the rest of my post? Because you are still using the unjustified assumption that the clocks start in a special rest frame.
This exchange reminds me of another special relativity doubter:
http://www.mathpages.com/home/kmath024/kmath024.htm
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For the benefit of readers just joining this thread, who don't have time to read through the previous 20 pages, a brief summary follows:
Blah blah blah.
You're wrong.
No, you're wrong.
You're wrong.
No, you're wrong.
You're wrong.
No, you're wrong.
You're wrong.
No, you're wrong.
...
...
...
You're wrong.
No, you're wrong.
-
For the benefit of readers just joining this thread, who don't have time to read through the previous 20 pages, a brief summary follows:
Hey, quite a ways back there were a couple of actually productive conversations that resulted in some relevant conclusions for the thread title.
Some have been summarized in the first post indicting how if you pick one frame (probably the CMB rest frame) and your FTL drives are constrained to be forward in time in that frame, then you get no paradoxes.
There was also a paper that was put forth as a denial of the time travel conclusion, that while the paper seemed to draw incorrect conclusions, some of the work did indicate that there could be a preferred direction rather than a preferred frame, basically meaning you can FTL to the left but not to the right basically making FTL a one way trip.
We don't know of anything that actually behaves like this, but at least we can describe some potential constraints for a new discovery that would allow some sort of FTL without completely contradicting known physics.
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All of the math I've seen indicates:
1) You can't travel back in time.
2) You can't travel faster than light.
But even with these limitations, you can still travel to another galaxy in just 30 years. Another 30 years to come back, and you can make the round trip within a single lifetime.
But you may not want to come back, since 5 million years would have passed on Earth.
In other words, we may want to stop thinking in terms of round trip missions. Instead, they may be like colonies that go out and explore until they find a place to settle. Once they leave, we never see them again.
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Some have been summarized in the first post indicting how if you pick one frame (probably the CMB rest frame) and your FTL drives are constrained to be forward in time in that frame, then you get no paradoxes.
Thanks meberbs. :)
Yeah guys. Have a look at the first post for a summary/index of what I think were the most relevant conclusions. I think we found a nice "good enough for SF" solution using either CMB rest frame or CMB temperature. I don't think there has been any other proposal that really describes the behaviour of its version of FTL in a clear way. (parallel universes were brought up but imply a very fuzzy and undefined relationship between what enters and exits FTL)
Also, as an aside, I think maintaining an index of key quotes to later messages in the OP is quite a nice technique. There are a bunch of threads eg on radiation mitigation and on atmospheric pressure and Oxygen partial pressure for a mars base that had a lot of good material, but it tended to get lost as the threads just grew and grew, and people restarted the conversations without consuming everything on the dozens of pages beforehand.
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Did you actually read the rest of my post? Because you are still using the unjustified assumption that the clocks start in a special rest frame.
This exchange reminds me of another special relativity doubter:
http://www.mathpages.com/home/kmath024/kmath024.htm
Wow. That is a long and sad journey for Dingle. It seems to me that he was not so much incapable of understanding relativity as that he stubbornly refused to do so. The more people tried to explain it to him the more defenses he erected. He went from an honest if misguided attempt to explain relativity to being convinced of a massive world wide conspiracy to cover up the flaws of relativity. His correspondents went from an honest attempt to explain it to him to total frustration and finally to silence.
I see the same trajectory in many others with ties to fringe science. The cold fusion mess is the best example in recent history. Who can forget Jed Rothwell's "cold fusion (sorry, need to stop here for a second and just say that I have to use stupid words to get my point across. I know that means I must have a weak argument, but that's why I use bad words)."?
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Some have been summarized in the first post indicting how if you pick one frame (probably the CMB rest frame) and your FTL drives are constrained to be forward in time in that frame, then you get no paradoxes.
Thanks meberbs. :)
Yeah guys. Have a look at the first post for a summary/index of what I think were the most relevant conclusions. I think we found a nice "good enough for SF" solution using either CMB rest frame or CMB temperature. I don't think there has been any other proposal that really describes the behaviour of its version of FTL in a clear way. (parallel universes were brought up but imply a very fuzzy and undefined relationship between what enters and exits FTL)
Also, as an aside, I think maintaining an index of key quotes to later messages in the OP is quite a nice technique. There are a bunch of threads eg on radiation mitigation and on atmospheric pressure and Oxygen partial pressure for a mars base that had a lot of good material, but it tended to get lost as the threads just grew and grew, and people restarted the conversations without consuming everything on the dozens of pages beforehand.
Assuming I am not restarting the conversation then, I am a bit baffled by the philosophical slant on speculations of new physics as summarized. The physical paradox, if you will, with a solution in general relativity - which can still be physically non-realizable since there is no principled way to eliminate unphysical solutions - that has a reference frame that admits matter-energy traveling above the universal speed limit is that there is no way (that I know of) to place said matter-energy at that speed within the frame. Because, you know, the universal speed limit (USL).
A principled method to pick physically realizable solutions in general relativity seems to include rejecting spacetimes that breaks special relativity, in the same way that principled methods to pick physically realizable solutions in quantum field physics includes rejecting fields that do so [ https://en.wikipedia.org/wiki/Quantum_field_theory ].
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Sorry Torbjorn.. I honestly couldn't parse most of what you just said. :)
Leave your principles at the door for this topic. This is not a discussion of whether FTL is realisable or how. It is just about resolving things like the grandfather paradox.
-
For the benefit of readers just joining this thread, who don't have time to read through the previous 20 pages, a brief summary follows:
Hey, quite a ways back there were a couple of actually productive conversations that resulted in some relevant conclusions for the thread title.
Some have been summarized in the first post indicting how if you pick one frame (probably the CMB rest frame) and your FTL drives are constrained to be forward in time in that frame, then you get no paradoxes.
There was also a paper that was put forth as a denial of the time travel conclusion, that while the paper seemed to draw incorrect conclusions, some of the work did indicate that there could be a preferred direction rather than a preferred frame, basically meaning you can FTL to the left but not to the right basically making FTL a one way trip.
We don't know of anything that actually behaves like this, but at least we can describe some potential constraints for a new discovery that would allow some sort of FTL without completely contradicting known physics.
Asside from it being interesting side discussion. Does it matter? I ask becasue in the end you only know if the proposed constraints are actual constraints after validating and carrying out additional tests on a real FTL device. Could turn out we have subtle holes in our understanding. Also could turn out that it is physically impossible to build a FTL device.
-
For the benefit of readers just joining this thread, who don't have time to read through the previous 20 pages, a brief summary follows:
Hey, quite a ways back there were a couple of actually productive conversations that resulted in some relevant conclusions for the thread title.
Some have been summarized in the first post indicting how if you pick one frame (probably the CMB rest frame) and your FTL drives are constrained to be forward in time in that frame, then you get no paradoxes.
There was also a paper that was put forth as a denial of the time travel conclusion, that while the paper seemed to draw incorrect conclusions, some of the work did indicate that there could be a preferred direction rather than a preferred frame, basically meaning you can FTL to the left but not to the right basically making FTL a one way trip.
We don't know of anything that actually behaves like this, but at least we can describe some potential constraints for a new discovery that would allow some sort of FTL without completely contradicting known physics.
Asside from it being interesting side discussion. Does it matter? I ask becasue in the end you only know if the proposed constraints are actual constraints after validating and carrying out additional tests on a real FTL device. Could turn out we have subtle holes in our understanding. Also could turn out that it is physically impossible to build a FTL device.
It matters for 2 things:
-writing hard sci-fi (which is what KelvinZero was after when starting this thread.) The preferred direction thing applies less to this since it is somewhat unintuitive, and I haven't figured out how to interpret the 3d generalization yet.
-The exercise is attempting to find holes in our understanding. Without some radical new discovery we are fairly certain we can't build an FTL device. This is figuring out what (unlikely) new discoveries would have to look like to allow FTL without contradicting causality or known experiments. It helps for keeping an open mind and improving our understanding.
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Add a 3rd clock to step 1 whose energy is never changed by any kicks and it remains in the initial rest frame. Then at the end of Scenario 2, the two clocks that are in motion will be running slower than the 3rd clock. Whereas, at the end of Scenario 1, they are all three running at the same rate, but have elapsed different times during the experiment. See the difference?
No, because, you can just have the third clock already moving with speed v instead. Your choice of relative speed for the third clock is arbitrary, and has no effect on anything. It is equivalent to picking the frame you are working in, having the clock moving at speed v to start with is what I did when I said "use the frame of clock 1(after the unnecessary step 1)" Everything therefore still remains unchanged.
They all agree at the end of both experiments, that the 3rd clock that didn't move elapsed the most time.
No, when clocks are spatially separated, there can be no agreement on the relative reading of the clocks, you would have to extend the scenario to bring the clocks together to make this statement, and the answer would depend on which clocks you accelerate in the process.
Did you actually read the rest of my post? Because you are still using the unjustified assumption that the clocks start in a special rest frame.
Given 2 clocks with a relative velocity that are spatially separated, we have an ambiguous situation. If we "assume" the 2 clocks were synchronized when they passed each other, this alone says nothing about the rate of either clock because it is only 1 event. Work must be done to one of the clocks to bring them back together. It is the clock that had no work done to it, that will have the longest elapsed time. Okay?
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It is the clock that had no work done to it, that will have the longest elapsed time. Okay?
That is true of a completed journey where the clocks end up in the same place. But that isn't exactly new. Of course you have to accelerate in order to travel a different path through space/time. It is simple geometry.
But the situation is still symmetric.
Say you have two spaceships with twin one in ship one and twin two in ship two. Now say both twins crawl into a hibernation unit after which one of the ships accelerate to some velocity away. The twins awaken to see relative velocity between them but don't know which of them accelerated.
So what can they do to determine who has the real velocity and slow clock? After all they see each others clock as slow. If twin one travels back to twin two he will find that the twin one clock is slow. But if twin two travels back to twin one he will find that the twin two clock is slow. Exactly reciprocal.
Under special relativity neither clock can be said to be slower or faster than the other until they end up at the same place. Yes it is the acceleration of one or the other that causes one clock to be slower. But it isn't some physical effect of acceleration on the clock mechanism that causes a clock to slow. Ultimately the speed of the clock depends on the path it takes through space/time and acceleration changes that path. It is simple geometry.
Now I understand that you want to have the speed of the clock depend on the motion through a local region of space relative to a center of mass. Well maybe you could make such a thing work but you have a very very VERY long way to go to get there. For example it isn't clear what you could possibly mean by "region of space". You talk about objects traveling through the earths gravitational field with velocities relative to the center of mass of the earth but in fact we are much deeper into the sun's gravity field than we are the earth's. Shouldn't we use the sun as the center of gravity of of our "region of space"? I think your whole idea of such a "region of space" is incoherent.
The whole point of a transform like the Galilean transform or the Lorentz transform is that it allows you to calculate how things look from any frame of reference at all. Until you define a mathematical WarpTech transform that defines your "region of space" and allows us to transform between between any region at all you have nothing. I think it will be more difficult than you think to come up with such a transform. But good luck.
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Given 2 clocks with a relative velocity that are spatially separated, we have an ambiguous situation.
If by ambiguous, you mean reciprocal, then yes. That is the point of reciprocity that you can't tell which is "moving" and it doesn't matter.
If we "assume" the 2 clocks were synchronized when they passed each other, this alone says nothing about the rate of either clock because it is only 1 event.
Really it says nothing at all other than that they had noted the time delta between their clocks when they first passed each other and you are subtracting it off for simplicity.
Work must be done to one of the clocks to bring them back together. It is the clock that had no work done to it, that will have the longest elapsed time. Okay?
As long as you allow "work done to" to include negative values of work, that is fine, though referring to it as the one that accelerated may be clearer and easier to generalize.
...You talk about objects traveling through the earths gravitational field with velocities relative to the center of mass of the earth but in fact we are much deeper into the sun's gravity field than we are the earth's. Shouldn't we use the sun as the center of gravity of of our "region of space"? I think your whole idea of such a "region of space" is incoherent.
The whole point of a transform like the Galilean transform or the Lorentz transform is that it allows you to calculate how things look from any frame of reference at all. Until you define a mathematical WarpTech transform that defines your "region of space" and allows us to transform between between any region at all you have nothing. I think it will be more difficult than you think to come up with such a transform. But good luck.
Exactly, this is one of the main things I have been trying to say, but haven't said clearly enough.
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I'm sorry if this was already mentioned somewhere in the previous pages, but I wonder if anyone here reads Sabine Hossenfelder's blog.
She wrote a quite interesting piece on FTL and paradoxes a couple of years ago (comments are fairly interesting too)
https://backreaction.blogspot.it/2015/06/does-faster-than-light-travel-lead-to.html (https://backreaction.blogspot.it/2015/06/does-faster-than-light-travel-lead-to.html)
I think her point could be summarized by saying that the way to solve such paradoxes is to acknowledge the fact that, for macroscopic objects, there exist a sort of "preferred frame" given by the unidirectionality of the arrow of time that is overimposed on top of fundamentally time-symmetric interactions.
She also posted a link to an article by Nemiroff and Russell where they calculate explicitly when the closed loop starts going back in time.
https://arxiv.org/abs/1505.07489 (https://arxiv.org/abs/1505.07489)
One surprising conclusion is that there's an interval of superluminal speeds that doesn't lead to time travel in the past.
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It is the clock that had no work done to it, that will have the longest elapsed time. Okay?
That is true of a completed journey where the clocks end up in the same place. But that isn't exactly new. Of course you have to accelerate in order to travel a different path through space/time. It is simple geometry.
But the situation is still symmetric.
Say you have two spaceships with twin one in ship one and twin two in ship two. Now say both twins crawl into a hibernation unit after which one of the ships accelerate to some velocity away. The twins awaken to see relative velocity between them but don't know which of them accelerated.
This is what I mean by "ambiguous". Just because they do not know which one accelerated does not mean that it didn't happen.
So what can they do to determine who has the real velocity and slow clock? After all they see each others clock as slow. If twin one travels back to twin two he will find that the twin one clock is slow. But if twin two travels back to twin one he will find that the twin two clock is slow. Exactly reciprocal.
Say it was twin one who accelerated and twin two did not. Didn't this acceleration affect his clock? If twin two accelerates to catch up to him, then when they meet and are at rest wrt each other, both of their clocks are running slower than before they went into hibernation. Had twin one returned to twin two, then the rate of their clocks would be the same as it was before hibernation. The situation is not symmetrical, it only "appears" to be because the set-up of the problem is ambiguous.
Under special relativity neither clock can be said to be slower or faster than the other until they end up at the same place. Yes it is the acceleration of one or the other that causes one clock to be slower. But it isn't some physical effect of acceleration on the clock mechanism that causes a clock to slow. Ultimately the speed of the clock depends on the path it takes through space/time and acceleration changes that path. It is simple geometry.
...
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I'm sorry if this was already mentioned somewhere in the previous pages, but I wonder if anyone here reads Sabine Hossenfelder's blog.
...
Hi Povel,
Looks like she has come to one of the same conclusions we did, with more math ;)
(Paradoxes are avoided if you require the CMB temperature to always be lower at your destination.. ie the universe has to be higher entropy and 'older' . Since relativistic travel also has this property, therefore no combination of this sort of ftl and relativistic travel could get you back to the same point before you left, ie when the universe was a bit hotter.)
I'll paste it into the OP as a reference.
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One reason I suspect there is no actual time travel involved in relativity, only an apparent time travel, is the behavior of current.
Let's take a current loop in the lab frame. When a current is applied to a wire the charge picks up a very small velocity. If all the current around the loop actually Lorentz contracts representing some time travel aspect we will get some serious change in charge in the lab frame and a non-conservation of charge. The reason for this is because if a Lorentz contraction happens all around the loop we get a time helix of charge where the perimeter is larger than 2*pi*r.
Such changes in charge of such a wire lead to massive voltage induced by local capacitance. V=Q/C .
There are some strict constraints on charge conservation which seem to suggest a lack of actual time travel, unless I am missing something fundamental about it. As such this may (depending on experimental evidence) preclude such time paradoxes from actually happening and just the local clock is being modified or slowed/sped back up some how with out actually allowing real time travel.
You will notice in Purcell's book "Electricity and Magnetism" for instance there appears to be no Lorentz contraction between charges during charge acceleration in a current loop. This appears to imply charge conservation.
(https://latex.codecogs.com/gif.latex?\begin{matrix}&space;\textsc{electrons/m}=\rho_{\,copper}&space;\cdot&space;(r^2&space;\pi)=8.49&space;\cdot&space;10^{28}&space;(0.0005^2&space;\cdot&space;3.14159)&space;\\&space;\textsc{columbs/electron}=1.60217662&space;\cdot&space;10^{-19}&space;\\&space;\textsc{columbs/m}=\textsc{electrons/m}\cdot&space;\textsc{columbs/electron}&space;\\&space;\textsc{m/s}_{charge}=(\textsc{columbs/s})/(\textsc{columbs/m})&space;\\&space;\textsc{Lorentz&space;contraction}=dL=L-L_o\sqrt{1-(v/c)^2}=L-L_o(v/c)\sqrt{1/(v/c)^2-1}&space;\\&space;(\textsc{columbs/m})\cdot(\text{dL}_{\,wire})=\textsc{change&space;in&space;charge&space;of&space;wire}&space;\end{matrix})
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One reason I suspect there is no actual time travel involved in relativity, only an apparent time travel, is the behavior of current.
Lets take a current loop in the lab frame. When a current is applied to a wire the charge picks up a very small velocity. If all the current around the loop actually Lorentz contracts representing some time travel aspect we will get some serious change in charge in the lab frame and a non-conservation of charge. The reason for this is because if a Lorentz contraction happens all around the loop we get a time helix of charge where the perimeter is larger than 2*pi*r.
This argument makes no sense.Time travel in special relativity doesn't happen because for time travel to happen, there needs to be FTL travel. In ordinary situations, things can't go FTL to begin with, so charges travelling in a loop will obviously say nothing about FTL.
Lorentz contraction does not predict any change in the charges in the wire, they will all be uniformly distributed in the lab frame just like you would expect. I am not sure how to clear up whatever misunderstanding led you to your conclusion, because your description includes phrases like "time helix of charge" which simply don't mean anything.
It is clear that you don't know what you are talking about here. You should also be able to realize this when you come to conclusions like "special relativity fails in this simple case," since scientists would have noticed that sometime in the last 100 years. Learning is good, so when you get to such a point showing your work and asking where you went wrong is good. Stating your work as if it was a fact is simply spreading ignorance, and has the potential to confuse other people who come by and don't have a strong physics background. It also reflects poorly on you, because instead of demonstrating a curiosity and desire to learn, it comes off as somewhat arrogant (I am having trouble finding the right word, it is basically like some form of self-centeredness where you either think you know a lot more than you do, or want to look like you know more than you do.)
Please stop making posts like this, it is doing nobody any good. Sharing ideas you had is fine, but your post is full of incorrect statements where you should be asking questions.
There is an interesting phenomenon called "hidden momentum" (http://gr.physics.ncsu.edu/files/babson_ajp_77_826_09.pdf) that happens in a current loop when fields cause the charges to move non-uniformly through the loop. I don't think you should bother reading the link I just posted though, at least not before you have spent some time learning basic relativity and intermediate electrodynamics, it simply wouldn't benefit you and you are likely to come away with more misunderstandings than learning.
One bit of advice: it is important to view knowledge as sort of a semantic tree — make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to.
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One reason I suspect there is no actual time travel involved in relativity, only an apparent time travel, is the behavior of current.
Lets take a current loop in the lab frame. When a current is applied to a wire the charge picks up a very small velocity. If all the current around the loop actually Lorentz contracts representing some time travel aspect we will get some serious change in charge in the lab frame and a non-conservation of charge. The reason for this is because if a Lorentz contraction happens all around the loop we get a time helix of charge where the perimeter is larger than 2*pi*r.
This argument makes no sense.Time travel in special relativity doesn't happen because for time travel to happen, there needs to be FTL travel. In ordinary situations, things can't go FTL to begin with, so charges travelling in a loop will obviously say nothing about FTL.
Lorentz contraction does not predict any change in the charges in the wire, they will all be uniformly distributed in the lab frame just like you would expect. I am not sure how to clear up whatever misunderstanding led you to your conclusion, because your description includes phrases like "time helix of charge" which simply don't mean anything.
It is clear that you don't know what you are talking about here. You should also be able to realize this when you come to conclusions like "special relativity fails in this simple case," since scientists would have noticed that sometime in the last 100 years. Learning is good, so when you get to such a point showing your work and asking where you went wrong is good. Stating your work as if it was a fact is simply spreading ignorance, and has the potential to confuse other people who come by and don't have a strong physics background. It also reflects poorly on you, because instead of demonstrating a curiosity and desire to learn, it comes off as somewhat arrogant (I am having trouble finding the right word, it is basically like some form of self-centeredness where you either think you know a lot more than you do, or want to look like you know more than you do.)
Please stop making posts like this, it is doing nobody any good. Sharing ideas you had is fine, but your post is full of incorrect statements where you should be asking questions.
There is an interesting phenomenon called "hidden momentum" (http://gr.physics.ncsu.edu/files/babson_ajp_77_826_09.pdf) that happens in a current loop when fields cause the charges to move non-uniformly through the loop. I don't think you should bother reading the link I just posted though, at least not before you have spent some time learning basic relativity and intermediate electrodynamics, it simply wouldn't benefit you and you are likely to come away with more misunderstandings than learning.
One bit of advice: it is important to view knowledge as sort of a semantic tree — make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to.
I think your projecting your self onto me.
One might surmise time travel is possible via traveling into the future using relativity. If they really think that then they also think an instant jump backwards while carrying their forward momentum will jump them backwards in time. The question is if there is any actual travel into some future time or not.
https://forum.nasaspaceflight.com/index.php?topic=43385.msg1706244#msg1706244
A time helix is the shortened length (pancaking) of charges because they exist via a gradient in time with in the loop, allowing more charge to exist in the loop. I am saying this seems to not be the case.
I suppose it's possible there is time travel for each individual charge not considering the entire perimeter of the loop. The time gradient exist on the charge with its forward velocity maybe causing more charge to exist perpendicular to its velocity but less forward and behind via some rotation of the charge out of our space/time (slowing its time) So for extra charge perpendicular to vector v we also have subtraction parallel to v resulting in a conserved quantity when integrating a charges flux. Leaving me unsure about actual time travel in that case.
Thanks for the link.
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I think your projecting your self onto me.
This is just a personal attack. My post was explaining that you don't understand what you are talking about, and nicely asking you to respect the fact that scientists have been working with relativity for over 100 years, and it won't be overturned with a back of the envelope calculation.
I wasn't taking your earlier comment about me seriously and was instead batting your comment back at you in jest. I made no claims to have overturned relativity. The calculation and discussion illustrates that Lorentz contraction doesn't happen for current accelerated in the lab frame which agrees with Purcell in his book. This is quite interesting to consider because one might naively think such a contraction might occur with a current loop. This says something about a time loop and charge conservation. Unfortunately, I think it fails because it considers the loop as a whole rather than the individual charges which I think individually have a time gradient each of their own that is responsible for the relativistic pancaking of the electric field of individual charges.
One might surmise time travel is possible via traveling into the future using relativity. If they really think that then they also think an instant jump backwards while carrying their forward momentum will jump them backwards in time. The question is if there is any actual travel into some future time or not.
Your statements here only serve to show that you do not have any understanding of relativity. It shows that you have not let go of your preconceptions, and therefore you are drawing conclusions that don't actually make sense. I won't explain in detail here in PM, especially because your response to my post indicates that you have no interest in learning.
It's your prerogative to presume that.
A time helix is the shortened length (pancaking) of charges because they exist via a gradient in time with in the loop, allowing more charge to exist in the loop. I am saying this seems to not be the case.
"Colorless green dreams sleep furiously." Your words form perfectly valid English, but they don't communicate anything. "gradient in time" is another term you seem to have made up. (There are probably contexts where that makes sense, but this is not one.)
Some good questions here. A gradient in time is a slope in time. A slope in time is what happens when you see an object with relativistic velocity. Such a length contracted object appears to exist in a sloped time. https://en.wikipedia.org/wiki/Length_contraction
see "Using time dilation"
Particularly the equation
(https://latex.codecogs.com/gif.latex?T'_{o}=L'_{o}/v&space;\mapsto&space;T'_{o}v=L'_{o})
with the primed frame being the length contracted frame. If we consider L' where some clock on board a length contracted (say a ship) is above our heads and synchronized with our clock at t=0 then if we advance position L'=x'_o+x' where x'_o=0 so T'=0 then a gradient in time exist on the ship via its velocity making events aboard non-synchronous. Conversely considering some point on the ship non-synchronous in time, times the velocity, gives the modified position of the ship so the ship (or any relativistic object) is contracted via the gradient in time. This gradient in time suggest a form of time travel but it always forces one into the future via the forwards direction. I suppose if the time travel is real then instantly jumping back while retaining ones forward velocity would send one into the past but this seems unlikely to be possible.
A time helix is a time slope around a curved path.
I suppose it's possible there is time travel for each individual charge not considering the entire perimeter of the loop. The time gradient exist on the charge with its forward velocity maybe causing more charge to exist perpendicular to its velocity but less forward and behind via some rotation of the charge out of our space/time (slowing its time) So for extra charge perpendicular to vector v we also have subtraction parallel to v resulting in a conserved quantity when integrating its flux. Leaving me unsure about actual time travel in that case.
This paragraph is basically gibberish again. You are conflating time dilation (a real, measured effect) with time travel (something predicted to happen if and only if FTL exists)
You are also talking about rotations through imaginary directions, rather than understanding that in the lab frame, the loop is some shape with constant density. In another frame, the loop will be distorted and have a different density. In any given frame all of the charge exists all of the time.
Lorentz transforms tilt the coordinate axes, but they are not a rotation, because instead of moving in the same direction, the axes squeeze towards each other.
Please stop pretending you know what you are talking about.
I was poking at the reason for electric field pancaking in the lab frame via the charge with velocity still having charge conserved and no Lorentz contraction between the charges. This seems to allow a time gradient to exist on the individual charges, allowing time travel on an individual charge level around the circular path and preserving charge.
I was poking if it were possible no actual time travel is involved and instead just the local clock was being modified, while an instant jump would still keep one stuck in the now (non time sloped) universe. This would restrict an instant jump to the proper time plane of the universe such as jump P to Q below. An instant jump where actual time travel is taking place might make it possible to jump forward or backward in time such as jump Q to R. The question being if any such jumps are allowed, can they move backward and forward in time or not.
(http://www.theculture.org/rich/sharpblue/images/causalityviolation.png)
This time gradient that exist on a relativistic object also suggest via the forward velocity who is aging faster. The fast moving object has time subtracted from its nose. Time subtracted from a forward velocity moves the nose backwards. The tail has time added which is the past so time is continually being subtracted from the object as it moves forward.
On board the object it seems the universe is length contracted but the universe time gradient is reversed. Its velocity toward the ship has time added with distance and the more so the further away contracting the universe. This added time represents the universe more rapidly aging. It is during acceleration this clock de-synchronization accelerates the ageing of the distant universe but via forward motion one actually travels there. Via the travel sure the universe clock at some point might tick slower but your traveling to points where the universe clock is way in advance of where you were.
The symmetric part is that your clock to the universe appears to tick slower and at the same time and at some point in the universe that clock appears to tick slower. The non symmetric part is the time gradient or ageing is non-symmetric. In front of the ship the universe moving towards is positive time times velocity while to the universe the ship nose moving towards is negative time times velocity. This gives the impression of who is actually moving slower through time and who is not.
The idea that locally light can always have v=c but non-locally, that light can change velocity, reaching some maximum velocity away from gravitational wells, seems to suggest via counter propagating photons from any frame, a frame between them where time ticks the fastest.
An FTL jump between frames maybe allowing instant distance traversal but because of the lack of actual progression through distance in the time gradient one instead jumps between as if there is no time gradient - allowing no progression of ones internal clock nor progression of the universe clocks via de-synchronization, bypassing time travel - eliminating paradoxes.
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It is the clock that had no work done to it, that will have the longest elapsed time. Okay?
That is true of a completed journey where the clocks end up in the same place. But that isn't exactly new. Of course you have to accelerate in order to travel a different path through space/time. It is simple geometry.
But the situation is still symmetric.
Say you have two spaceships with twin one in ship one and twin two in ship two. Now say both twins crawl into a hibernation unit after which one of the ships accelerate to some velocity away. The twins awaken to see relative velocity between them but don't know which of them accelerated.
This is what I mean by "ambiguous". Just because they do not know which one accelerated does not mean that it didn't happen.
It doesn't matter if it happened or not. The only thing that matters is that at the start there is a relative velocity between the 2 clocks. You cannot define an experiment that can tell which one accelerated, because there is literally nothing physically different between them.
So what can they do to determine who has the real velocity and slow clock? After all they see each others clock as slow. If twin one travels back to twin two he will find that the twin one clock is slow. But if twin two travels back to twin one he will find that the twin two clock is slow. Exactly reciprocal.
Say it was twin one who accelerated and twin two did not. Didn't this acceleration affect his clock? If twin two accelerates to catch up to him, then when they meet and are at rest wrt each other, both of their clocks are running slower than before they went into hibernation. Had twin one returned to twin two, then the rate of their clocks would be the same as it was before hibernation. The situation is not symmetrical, it only "appears" to be because the set-up of the problem is ambiguous.
The bolded statements are false. You are stating that in one case their clocks are both ticking "slower" at the end and in the other they are both ticking at the "original rate" but there is actually no way to tell these situations apart, because the only physical fact is that after they meet up and match speeds, they both are ticking at the same rate as each other. The situation is truly symmetric and there is no ambiguity in the final results. (Defining ambiguity as: something physically and measurably different between the final states that is undefined due to lack of sufficient initial conditions)
You literally just made the same claim previously, and I already explained exactly why it was wrong, you keep picking one frame, doing all of the work in that frame, and refuse to recognize that there is nothing special about the frame that you are picking:
Add a 3rd clock to step 1 whose energy is never changed by any kicks and it remains in the initial rest frame. Then at the end of Scenario 2, the two clocks that are in motion will be running slower than the 3rd clock. Whereas, at the end of Scenario 1, they are all three running at the same rate, but have elapsed different times during the experiment. See the difference?
No, because, you can just have the third clock already moving with speed v instead. Your choice of relative speed for the third clock is arbitrary, and has no effect on anything. It is equivalent to picking the frame you are working in, having the clock moving at speed v to start with is what I did when I said "use the frame of clock 1(after the unnecessary step 1)" Everything therefore still remains unchanged.
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It is the clock that had no work done to it, that will have the longest elapsed time. Okay?
That is true of a completed journey where the clocks end up in the same place. But that isn't exactly new. Of course you have to accelerate in order to travel a different path through space/time. It is simple geometry.
But the situation is still symmetric.
Say you have two spaceships with twin one in ship one and twin two in ship two. Now say both twins crawl into a hibernation unit after which one of the ships accelerate to some velocity away. The twins awaken to see relative velocity between them but don't know which of them accelerated.
This is what I mean by "ambiguous". Just because they do not know which one accelerated does not mean that it didn't happen.
It doesn't matter if it happened or not. The only thing that matters is that at the start there is a relative velocity between the 2 clocks. You cannot define an experiment that can tell which one accelerated, because there is literally nothing physically different between them.
So what can they do to determine who has the real velocity and slow clock? After all they see each others clock as slow. If twin one travels back to twin two he will find that the twin one clock is slow. But if twin two travels back to twin one he will find that the twin two clock is slow. Exactly reciprocal.
Say it was twin one who accelerated and twin two did not. Didn't this acceleration affect his clock? If twin two accelerates to catch up to him, then when they meet and are at rest wrt each other, both of their clocks are running slower than before they went into hibernation. Had twin one returned to twin two, then the rate of their clocks would be the same as it was before hibernation. The situation is not symmetrical, it only "appears" to be because the set-up of the problem is ambiguous.
The bolded statements are false. You are stating that in one case their clocks are both ticking "slower" at the end and in the other they are both ticking at the "original rate" but there is actually no way to tell these situations apart, ....
Theoretically, the clock that was accelerated will have a higher temperature relative to the CMB temperature, because when it was accelerated, provided it was accelerated long enough to achieve equilibrium with the vacuum, the Unruh radiation will have elevated its temperature. So there is an experiment that can be done to tell which one was accelerated. It just has to be extremely sensitive.
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Theoretically, the clock that was accelerated will have a higher temperature relative to the CMB temperature, because when it was accelerated, provided it was accelerated long enough to achieve equilibrium with the vacuum, the Unruh radiation will have elevated its temperature. So there is an experiment that can be done to tell which one was accelerated. It just has to be extremely sensitive.
So now you are using the CMB as your special frame, which is at least better defined than what you had been using before. (Although it doesn't help your argument when you keep casually changing the definition of your special frame.) You aren't actually defining anything special about this frame though. There are multiple problems with what you are saying:
-"higher temperature relative to the CMB temperature" does not make sense/ is not relevant. The CMB temperature is 2.7 K. Most things are higher temperature than that. If you are moving relative to the CMB, the CMB temperature will be hotter in some directions and colder in others, but basically will average out.
-"provided it was accelerated long enough to achieve equilibrium with the vacuum," How long it was accelerated for has nothing to do with whether it radiated off enough heat to lower its temperature to 2.7 K.
-"So there is an experiment that can be done to tell which one was accelerated. It just has to be extremely sensitive." We have measured motion relative to the CMB, it is not that difficult. There is no physics that is a function of motion relative to the CMB (not counting the miniscule difference in radiation pressure that results). Relativity applies equally well in frames moving with respect to the CMB or not.
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I resolve resolutely not to let paradox push me around. :) Instead i suggest showing paradox who's boss.
It is entirely possible that the appearance of paradox is itself a indicator that something is not understood enough; that something has been overlooked. And it may well be that that thing is in the picture of how things work in "established science." Then the paradox is a mirage that fades as you approach it. It does not always have to accrue to an experimenter or observer of something weird. I would be surprised if finding something new didn't in someway tilt established science at least to a small degree. new doesn't mean old.
And with FTL even though i knew reference frames were a bear i had no idea i was dealing with a mega-fauna version of a bear.
People very very often reverse the reference frames for the effects of time dilation for a traveler traveling to a distal star from earth. Simple things like who ages and who doesn't or thinking that both do or don't. i spend pages and days arguing that over and over with lots of people who should know better. And that is one of the easiest bits WRT relativity to understand.
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(To anyone confused by the chain between me and dustinthewind: I sent him a PM rather than a public response because I found his response inappropriate, he was quoting from that PM. That is fine, since most of the PM is what I would have said in public anyway.)
I think your projecting your self onto me.
This is just a personal attack. My post was explaining that you don't understand what you are talking about, and nicely asking you to respect the fact that scientists have been working with relativity for over 100 years, and it won't be overturned with a back of the envelope calculation.
I wasn't taking your earlier comment about me seriously and was instead batting your comment back at you in jest.
I was not joking. You do not understand basic aspects of relativity. To use the analogy I quoted, you keep trying to hang up leaves on a tree where you are missing the trunk. I pointed out specifically multiple places where your statements simply contradict relativity. Your statement in "jest" is literally equivalent to the "I'm rubber you're glue" statement kids use when they don't have a meaningful response. If you don't want a serious discussion, you are in the wrong place.
I made no claims to have overturned relativity. The calculation and discussion illustrates that Lorentz contraction doesn't happen for current accelerated in the lab frame which agrees with Purcell in his book.
The second sentence you wrote says "a basic, universal feature of special relativity doesn't happen in a common situation." That is a claim that you have overturned relativity. There is no length contraction measured in the lab frame because the lab frame is by definition not moving. The electrons are spread out in the wire in a uniform density. From the frame of an electron, the wire is length contracted and the density of the electrons appears higher, but still uniform (for a straight wire). You are misunderstanding what you are reading. The rest of your paragraph is extrapolating from this misunderstanding to greater misunderstandings.
One might surmise time travel is possible via traveling into the future using relativity. If they really think that then they also think an instant jump backwards while carrying their forward momentum will jump them backwards in time. The question is if there is any actual travel into some future time or not.
Your statements here only serve to show that you do not have any understanding of relativity. It shows that you have not let go of your preconceptions, and therefore you are drawing conclusions that don't actually make sense. I won't explain in detail here in PM, especially because your response to my post indicates that you have no interest in learning.
It's your prerogative to presume that.
You have made repeated statements that incorrectly describe what relativity concludes, and indicate that you have a variety of misconceptions about relativity that you need to unlearn. This is not a presumption but a fact about what you have demonstrated.
A time helix is the shortened length (pancaking) of charges because they exist via a gradient in time with in the loop, allowing more charge to exist in the loop. I am saying this seems to not be the case.
"Colorless green dreams sleep furiously." Your words form perfectly valid English, but they don't communicate anything. "gradient in time" is another term you seem to have made up. (There are probably contexts where that makes sense, but this is not one.)
Some good questions here. A gradient in time is a slope in time.
Yes, slope is a simplistic definition for gradient that in certain cases has the exact same meaning. This word replacement does not change the fact that the phrase is meaningless.
In physics gradient means: "an increase or decrease in the magnitude of a property (e.g., temperature, pressure, or concentration) observed in passing from one point or moment to another."
The mathematical counterpart to that definition is: "the vector formed by the operator ∇ acting on a scalar function at a given point in a scalar field."
Passing between moments doesn't make sense because we are already talking about time. Passing between points doesn't apply, because time dilation is not a function of position. You are missing the "scalar field" (and velocity is not a scalar field, it is sometimes a vector field, but in this case it isn't even a field).
If we were discussing general relativity, you could use the gravitational field to define the gradient in the rate that time passes at different points, excluding velocity dependent effects. We aren't discussing general relativity, and are discussing the velocity dependent effects that would be excluded though.
A slope in time is what happens when you see an object with relativistic velocity. Such a length contracted object appears to exist in a sloped time.
No. Time dilation and length contraction are things that are observed as differences between frames. When calculating a slope (or gradient) you need to divide the change in the thing you care about by the change in another thing. You haven't defined the second thing. It can't be space or time, and velocity doesn't work either, because different frames are just different perspectives, they are not something that is physically different. You pick a frame and use it, not gradually change between them. (You could be working with non-inertial frames, that change constantly, but that is needless complication, and not what was being discussed.)
a form of time travel but it always forces one into the future via the forwards direction. I suppose if the time travel is real then instantly jumping back while retaining ones forward velocity would send one into the past but this seems unlikely to be possible.
Traveling forward in time is not time travel at least not in any different way than what you normally experience. The instant jump is what is non-physical and impossible, and it turns out that you need 2 of them in special relativity to actually get to your own past. (Or special situations in general relativity usually needing negative energy density to get "closed timelike curves")
I suppose it's possible there is time travel for each individual charge not considering the entire perimeter of the loop. The time gradient exist on the charge with its forward velocity maybe causing more charge to exist perpendicular to its velocity but less forward and behind via some rotation of the charge out of our space/time (slowing its time) So for extra charge perpendicular to vector v we also have subtraction parallel to v resulting in a conserved quantity when integrating its flux. Leaving me unsure about actual time travel in that case.
This paragraph is basically gibberish again. You are conflating time dilation (a real, measured effect) with time travel (something predicted to happen if and only if FTL exists)
You are also talking about rotations through imaginary directions, rather than understanding that in the lab frame, the loop is some shape with constant density. In another frame, the loop will be distorted and have a different density. In any given frame all of the charge exists all of the time.
Lorentz transforms tilt the coordinate axes, but they are not a rotation, because instead of moving in the same direction, the axes squeeze towards each other.
Please stop pretending you know what you are talking about.
I was poking at the reason for electric field pancaking in the lab frame via the charge with velocity still having charge conserved and no Lorentz contraction between the charges. This seems to allow a time gradient to exist on the individual charges, allowing time travel on an individual charge level around the circular path and preserving charge.
I was poking if it were possible no actual time travel is involved and instead just the local clock was being modified, while an instant jump would still keep one stuck in the now (non time sloped) universe. This would restrict an instant jump to the proper time plane of the universe such as jump P to Q below. An instant jump where actual time travel is taking place might make it possible to jump forward or backward in time such as jump Q to R. The question being if any such jumps are allowed, can they move backward and forward in time or not.
Instant jumps do move through time. They can't not. (Note the double negative.) No frame is special, and there is always a frame where it is backwards in time (And the reverse instant jump in that frame is backwards in time to the original frame.)
I can't go through the rest of what you wrote, because "gradient in time" "time helix" and other things you wrote are still gibberish. You should go find an introduction to relativity textbook and study it or some other resource. You have insisted on using terms that you made up when there already is an accessible knowledge base out there you can learn from with established terminology. Unless you are willing to go back to the beginning and learn to speak the language that everyone else uses, it will be impossible to communicate with you.
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I resolve resolutely not to let paradox push me around. :) Instead i suggest showing paradox who's boss.
It is entirely possible that the appearance of paradox is itself a indicator that something is not understood enough; that something has been overlooked. And it may well be that that thing is in the picture of how things work in "established science." Then the paradox is a mirage that fades as you approach it. It does not always have to accrue to an experimenter or observer of something weird. I would be surprised if finding something new didn't in someway tilt established science at least to a small degree. new doesn't mean old.
I agree, many paradoxes are not paradoxes the "twin paradox" is a good example, it is only a paradox if you don't think it through completely.
And with FTL even though i knew reference frames were a bear i had no idea i was dealing with a mega-fauna version of a bear.
People very very often reverse the reference frames for the effects of time dilation for a traveler traveling to a distal star from earth. Simple things like who ages and who doesn't or thinking that both do or don't. i spend pages and days arguing that over and over with lots of people who should know better. And that is one of the easiest bits WRT relativity to understand.
I am having trouble telling if you understand it yourself. There simply isn't a meaningful answer unless they come back together. When they are separated neither can be determined as "older or younger," which is the most basic part of special relativity, that no frame is special, and different frames don't agree on what "simultaneous" means for spatially separated events. (This is the most fundamental part of relativity, but not the simplest, since it seems to be the root of the most confusion.)
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You know there is a simpler way to see the relativity of simultaneity than the twin paradox.
Say there are two twins in two ships motionless with respect to each other and some distance apart. They look at each other's clock and see that they are both showing the same time and time is passing at the same rate.
Now say a third ship is traveling at a high velocity with respect to the twin ships. It looks at the two twins clocks and see that they are both slowed by the same amount and thus time is passing for them at the same rate as each other. But what it also notices is that the clocks are no longer showing the same time. Also the ships are closer together.
This is where the relativity of simultaneity lives. Relative velocity means that the time space axis is rotated with respect to each other. That means some of the space between the twin ships has disappeared but some distance in time between the ships has been created between them. At least from the point of view of the third ship. This weirdness is called Minkowski space. In Euclidean geometry distance is defined as:
D^2 = X^2 + Y^2 + Z^2.
Distance in Minkowski space is defined differently. First you add time as a coordinate. Then just for fun you make the time coordinate negative and multiply it by the speed of light squared. so you have:
D^2 = X^2 + Y^2 + Z^2 - (CT)^2
All of the effects of special relativity are just the results of this new kind of geometry. In this geometry faster than light speed is time travel. Not as a physical effect of motion but as a mathematical fact of geometry.
Now if you want to explain the slow clocks as a real effect caused by absolute motion then you also have to show how two ships motionless with respect to each other can have clocks offset from each other... and not know it.
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I resolve resolutely not to let paradox push me around. :) Instead i suggest showing paradox who's boss.
It is entirely possible that the appearance of paradox is itself a indicator that something is not understood enough; that something has been overlooked. And it may well be that that thing is in the picture of how things work in "established science." Then the paradox is a mirage that fades as you approach it. It does not always have to accrue to an experimenter or observer of something weird. I would be surprised if finding something new didn't in someway tilt established science at least to a small degree. new doesn't mean old.
I agree, many paradoxes are not paradoxes the "twin paradox" is a good example, it is only a paradox if you don't think it through completely.
And with FTL even though i knew reference frames were a bear i had no idea i was dealing with a mega-fauna version of a bear.
People very very often reverse the reference frames for the effects of time dilation for a traveler traveling to a distal star from earth. Simple things like who ages and who doesn't or thinking that both do or don't. i spend pages and days arguing that over and over with lots of people who should know better. And that is one of the easiest bits WRT relativity to understand.
I am having trouble telling if you understand it yourself. There simply isn't a meaningful answer unless they come back together. When they are separated neither can be determined as "older or younger," which is the most basic part of special relativity, that no frame is special, and different frames don't agree on what "simultaneous" means for spatially separated events. (This is the most fundamental part of relativity, but not the simplest, since it seems to be the root of the most confusion.)
What i mean is on earth time passes at it's normal pace. on a ship traveling sufficiently fast the trips seems to take very little time. but when the ship returns they find that the earth has aged very roughly eight years plus whatever time was spent at Alpha Centauri. The confused people i referred to get this simple effect backwards or even worse. In other words they think time dilation effects work on non relativistic velocity innocent bystander observers.
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Something interesting to note is Einstein used a frame in which the stars were at rest or moving slow w.r.t. light to derive general relativity.
Einstein’s 1917 Static Model of the Universe: A Centennial Review (https://scholar.google.com/scholar?cluster=6636826552109387153&hl=en&as_sdt=0,26)
A third assumption is that there exists a reference frame in which matter is at rest: this
assumption is based on what Einstein terms the “most important fact we draw from
experience as to the distribution of matter”, the low velocities of the stars:
The most important fact that we draw from experience as to the distribution of matter
is that the relative velocities of the stars are very small as compared with the velocity of
light. So I think that for the present we may base our reasoning upon the following
approximate assumption. There is a system of reference relatively to which matter may
be looked upon as being permanently at rest.
Einstein then embarks on a simple analysis in which he derives values for the components
of the field equation tensors
...
Thus Einstein’s assumption that “there is a system of reference relative to which matter may be looked upon as being permanently at rest” seems reasonable. I
This would seem to indicate a frame in which the stars are near rest, and and other frames in which one is near v=c. Not sure that would mean the frame is necessarily homogeneous but it appears to be stated.
There also appears to be an experiment in which a test of the dipole electric field of a solenoid in the lab frame did turn up some interesting results. Also had some unusual readings in the lab frame with a solenoid and very low capacitance capacitor myself but didn't pursue it at the time.
Energy-dependent metric for gravitation and the breakdown of local Lorentz invariance (https://scholar.google.com/scholar?cluster=6917963573761996005&hl=en&as_sdt=0,26)
We analyze the data on the comparison of clock rates between a ∞ying clock and a clock at ground, carried out by Alley and coworkers at the end of '70's .The flt to such data is in favour of an energy-dependent metric for gravitation. We discuss also the results of a recently proposed electromagnetic test of breakdown of local Lorentz invariance - based on the detection of a voltage induced by a stationary magnetic fleld - and show that the obtained positive evidence for such an efiect seems to support the derived form of the energy-dependent gravitational metric.
A test I believe might indicate a relative velocity with respect to such a frame would be to measure the static dipole electric field of a magnetic field. In the lab frame. If there is no difference in clock rates for the individual charges in the lab frame no dipole electric field should form in the lab frame.
However if for some reason the clock of a charge sped up moving in some particular direction in the lab, as opposed to another direction, there should be a corresponding dipole electric field to go with it.
Such an experiment with sufficient sensitivity, I believe could determine velocity relative to a local field that determines the clock rate.
I suspect existing in a gravity field may induce some effect but I would be curious of it's exact orientation of the lab frame dipole electric field. Parallel or perpendicular to Earth's surface.
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approximate assumption
As Einstein stated, it was an approximate assumption made while deriving a specific solution to his equations. It allows for picking a frame that makes the math easier, but it does not make that frame "special" as you are presenting it. Also if you actually bothered to read the paper you referenced, you would see that his assumptions were incorrect for our universe, since the universe is expanding. In fact the last sentence you quoted was immediately preceded by:
Indeed, many years were to elapse before the discovery of a linear relation between the recession of the distant galaxies and their distance (Hubble 1929), the first evidence for a non-static universe.
The entire paragraph it was a part of was explaining that our modern knowledge that his assumptions do not describe our universe was not available to Einstein, so his assumptions were reasonable from his perspective. By pulling that sentence out of context you completely changed its meaning.
There also appears to be an experiment in which a test of the dipole electric field of a solenoid in the lab frame did turn up some interesting results. Also had some unusual readings in the lab frame with a solenoid and very low capacitance capacitor myself but didn't pursue it at the time.
Their paper seems to be discussing a distorted metric in the presence of gravity and reconciling this with certain experiments. We already know about this, it is called general relativity, so it is strange that they repeatedly insist on comparing to Minkowski space-time, when it is known that gravitational potential causes time dilation.
As for the circuit, I would find it somewhat surprising, but it is possible they found a case where the difference in gravitational potential energy could affect the circuit. It isn't worth it for me to go through since there are multiple indicators that they are crackpots, and the general idea was already worked out in detail 100 years ago.
As for your experiment, it is really, and truly irrelevant. Actually, none of what you just posted is relevant to this thread, especially since it is a combination of misinterpretation and meaningless claims.
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approximate assumption
As Einstein stated, it was an approximate assumption made while deriving a specific solution to his equations. It allows for picking a frame that makes the math easier, but it does not make that frame "special" as you are presenting it. Also if you actually bothered to read the paper you referenced, you would see that his assumptions were incorrect for our universe, since the universe is expanding. In fact the last sentence you quoted was immediately preceded by:
Indeed, many years were to elapse before the discovery of a linear relation between the recession of the distant galaxies and their distance (Hubble 1929), the first evidence for a non-static universe.
The entire paragraph it was a part of was explaining that our modern knowledge that his assumptions do not describe our universe was not available to Einstein, so his assumptions were reasonable from his perspective. By pulling that sentence out of context you completely changed its meaning.
If you read the paper then you know that solution was only lacking the cosmological constant which he adds later. This doesn't change the frame work in which he lays out his conditions (density, stars with low velocity that define a metric, closed universe, 𝜆).
Einstein soon found that the hypothesis of closed spatial geometry was not sufficient to achieve a successful relativistic model of the universe. A consistent solution could only be achieved with the introduction of
an additional term 𝜆𝑔𝜇𝜈 to the field equations, where 𝜆 represented a constant that later became known as the ‘cosmological constant’. Thus Einstein’s model appears to have evolved according to the following sequence of assumptions: uniform, static distribution of matter → closed spatial geometry → introduction of additional term to the field equations.
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“That term is necessary only for the purpose of making possible a quasi-static distribution of matter, as required by the fact of the small velocities of the stars”
...
... Einstein gave his first physical interpretation of the cosmological term, namely that of a negative mass density: “In terms of the Newtonian theory…a modification of the theory is required such that “empty space” takes the role of gravitating negative masses which are distributed all over the interstellar space” (Einstein 1918c)
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However, the error may be significant with regard to Einstein’s interpretation of the term. Where he intended to introduce a term to the field equations representing an attenuation of the gravitational interaction at large distances, he in fact introduced a term representing a very different effect. Indeed, the later interpretation of the cosmological term as representing a tendency for empty space to expand would have been deeply problematic for Einstein in 1917, given his understanding of Mach’s Principle at the time.
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“It appears to me that one can raise a grave argument against the admissibility of this solution…..In my opinion, the general theory of relativity is a satisfying system only if it shows that the physical qualities of space are completely determined by matter alone. Therefore no 𝑔𝜇𝜈- field must exist (that is no space-time continuum is possible) without matter that generates it” (Einstein 1918f).
expansion of space sounds a lot like expansion of a metric. It also seems to suggest the matter generates the metric. All I am suggesting is that this proper metric generated by the low velocity stars gives a metric of fastest time progression. Moving relative to is distorts your time so that your time passes slower and gives the illusion of a distorted metric via your distorted clock. You will notice in the graphics of the moving ship that its the non-distorted metric where time passes faster.
With that said, I reiterate the idea that an ftl jump, when one is moving, would move one with out the progression of ones own internal clock. With out the actual progression of ones own internal clock to give the illusion of a distorted metric, then one does not appear to move through time. Instead it would be a classical jump along the metric with no time travel allowed. So no jumping backward, with forward momentum, to send one back in time, circumnavigating any paradox. (Still some serious problems with instant jumps though.)
There also appears to be an experiment in which a test of the dipole electric field of a solenoid in the lab frame did turn up some interesting results. Also had some unusual readings in the lab frame with a solenoid and very low capacitance capacitor myself but didn't pursue it at the time.
Their paper seems to be discussing a distorted metric in the presence of gravity and reconciling this with certain experiments. We already know about this, it is called general relativity, so it is strange that they repeatedly insist on comparing to Minkowski space-time, when it is known that gravitational potential causes time dilation.
As for the circuit, I would find it somewhat surprising, but it is possible they found a case where the difference in gravitational potential energy could affect the circuit. It isn't worth it for me to go through since there are multiple indicators that they are crackpots, and the general idea was already worked out in detail 100 years ago.
As for your experiment, it is really, and truly irrelevant. Actually, none of what you just posted is relevant to this thread, especially since it is a combination of misinterpretation and meaningless claims.
I wouldn't be so quick to just dismiss them as crackpots. It is relevant with respect to possible detection of motion through some form of a metric.
New Experimental Results on the Lower Limits of Local Lorentz Invariance
Fabio Cardone,1,2,3 Roberto Mignani,4−7 and Renato Scrimaglio1
However—at the light of the discussion of Sec. 5.2—the parameters (23) and (29) have to be regarded actually as the result of two contributions to the LLI breaking effect, one of gravitational ...
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Needless to say, the experiment must be independently repeated,
before one can claim that a LLI breakdown was actually observed.
We attempted an explanation of the results we found in terms of the
phenomenological metrics of electromagnetic and gravitational interactions
derived in the framework of DSR. If this interpretation is sound, we can
state that the LLI violation is expected to occur below an energy threshold
E0,e.m. ≈5µeV. In other words, contrarily to what commonly believed, LLI
breakdown (at least for electromagnetic interaction) would occur at low,
not at high, energies. This would explain why it was not observed before,
and implies that LLI violation would not affect dramatically most of the
phenomena in high-energy physics, astrophysics and cosmology.
Finally, we expect that the effect of LLI breakdown we seemingly
observed may affect some photon interference results, in particular the
photon–photon cross section. This seems indeed to be the case.(33)
Several citations on their work it appears.
Some more related:
https://scholar.google.com/scholar?cites=9205319355811967999&as_sdt=5,26&sciodt=0,26&hl=en
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One reason I suspect there is no actual time travel involved in relativity, only an apparent time travel, is the behavior of current.
Lets take a current loop in the lab frame. When a current is applied to a wire the charge picks up a very small velocity. If all the current around the loop actually Lorentz contracts representing some time travel aspect we will get some serious change in charge in the lab frame and a non-conservation of charge. The reason for this is because if a Lorentz contraction happens all around the loop we get a time helix of charge where the perimeter is larger than 2*pi*r.
This argument makes no sense.Time travel in special relativity doesn't happen because for time travel to happen, there needs to be FTL travel. In ordinary situations, things can't go FTL to begin with, so charges travelling in a loop will obviously say nothing about FTL.
Lorentz contraction does not predict any change in the charges in the wire, they will all be uniformly distributed in the lab frame just like you would expect. I am not sure how to clear up whatever misunderstanding led you to your conclusion, because your description includes phrases like "time helix of charge" which simply don't mean anything.
It is clear that you don't know what you are talking about here. You should also be able to realize this when you come to conclusions like "special relativity fails in this simple case," since scientists would have noticed that sometime in the last 100 years. Learning is good, so when you get to such a point showing your work and asking where you went wrong is good. Stating your work as if it was a fact is simply spreading ignorance, and has the potential to confuse other people who come by and don't have a strong physics background. It also reflects poorly on you, because instead of demonstrating a curiosity and desire to learn, it comes off as somewhat arrogant (I am having trouble finding the right word, it is basically like some form of self-centeredness where you either think you know a lot more than you do, or want to look like you know more than you do.)
Please stop making posts like this, it is doing nobody any good. Sharing ideas you had is fine, but your post is full of incorrect statements where you should be asking questions.
There is an interesting phenomenon called "hidden momentum" (http://gr.physics.ncsu.edu/files/babson_ajp_77_826_09.pdf) that happens in a current loop when fields cause the charges to move non-uniformly through the loop. I don't think you should bother reading the link I just posted though, at least not before you have spent some time learning basic relativity and intermediate electrodynamics, it simply wouldn't benefit you and you are likely to come away with more misunderstandings than learning.
One bit of advice: it is important to view knowledge as sort of a semantic tree — make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to.
This hidden momentum sounds a lot like the momentum of the charges set in motion where that motion continues. Setting them in motion sends out an impulse of equal and opposite effect on similar charges (via light) so in accelerating them they send out some change in momentum but they store the equal and opposite momentum in their relativistic field. Stopping them causes the relativistic emission of that counter momentum and that stored internal momentum goes to zero. So it fits the mechanical, magnetic-relativistic nature, stored momentum isn't electrodynamic (yet), u=store energy density of moving charges and field, v=charge velocity. In the case of a current loop it seems possible they have absolute velocity in the loop.
The relativistic hidden momentum of a particle in motion, related to its velocity is interesting. Most matter having charge even via nuclear decay. And the pancaking of relativistic electric fields being like the Lorentz effect could describe their charges also having velocity and slowed clock.
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approximate assumption
As Einstein stated, it was an approximate assumption made while deriving a specific solution to his equations. It allows for picking a frame that makes the math easier, but it does not make that frame "special" as you are presenting it. Also if you actually bothered to read the paper you referenced, you would see that his assumptions were incorrect for our universe, since the universe is expanding. In fact the last sentence you quoted was immediately preceded by:
Indeed, many years were to elapse before the discovery of a linear relation between the recession of the distant galaxies and their distance (Hubble 1929), the first evidence for a non-static universe.
The entire paragraph it was a part of was explaining that our modern knowledge that his assumptions do not describe our universe was not available to Einstein, so his assumptions were reasonable from his perspective. By pulling that sentence out of context you completely changed its meaning.
If you read the paper then you know that solution was only lacking the cosmological constant which he adds later. This doesn't change the frame work in which he lays out his conditions (density, stars with low velocity that define a metric, closed universe, 𝜆).
No, if you read the paper you certainly did not comprehend it. the assumptions Einstein used were wrong and the paper explained why. The cosmological constant is necessary to have general relativity allow the solutions Einstein came up with, but later Einstein denounced the cosmological constant because it was found that the solution of a static universe does not describe our universe, and his assumptions were wrong. It was only determined to be necessary for opposite reasons (accelerating expansion measured) after his death.
Your statement here does not even address the points that I made in my post.
expansion of space sounds a lot like expansion of a metric.
This is a tautology, a metric is how you describe the shape of spacetime.
It also seems to suggest the matter generates the metric.
This is part of one of the most basic explanations of general relativity. The distribution of matter determines the curvature of spacetime. However, Einstein's statement "In my opinion, the general theory of relativity is a satisfying system only if ..." seems to be what you are basing this on, even though this quote is from a criticism he made of someone else's solution to the GR equations, when his criticism was actually what was wrong.
All I am suggesting is that this proper metric generated by the low velocity stars gives a metric of fastest time progression. Moving relative to is distorts your time so that your time passes slower and gives the illusion of a distorted metric via your distorted clock. You will notice in the graphics of the moving ship that its the non-distorted metric where time passes faster.
Every sentence in this quote is wrong. There is nothing special about the frame of those stars other than the math being easier, but this is inapplicable to the universe we live in anyway. Your description that clock rates all must be relative to this frame is the exact opposite of the principle of relativity, and therefore contradictory. Your final statement simply confuses things because you are then seem to be talking about spacetime diagrams in special relativity, and neither frame has a distorted metric in that case. In fact they have the exact same metric. Also, neither is the "one" that has its axes tilted, because you can validly and symmetrically draw either frame as the one with the straight axes.
With that said, I reiterate the idea that an ftl jump, when one is moving,
The phrase "when one is moving" makes your entire statement wrong. There simply is no special frame in reality to measure motion relative to, and that is the basis of relativity. (We have already covered in this thread that if you define some special frame that a magic FTL drive must move forward in time in then paradoxes are avoided)
I wouldn't be so quick to just dismiss them as crackpots. It is relevant with respect to possible detection of motion through some form of a metric.
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Several citations on their work it appears.
There didn't seem to be any citations on the first paper you posted. There are multiple things indicating that they fall somewhere on the crackpot spectrum:
-discussing a situation clearly described by GR and only mentioning GR once in passing, never comparing their results to GR.
-They refer to c^4/G as the "Kostro constant" a term only they seem to use. (The constant itself shows up in the Einstein field equations, but doesn't need a name)
-9 citations for that new paper is not exactly a stunning endorsement (some were from themselves).
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What then do you think about Minkowski space or metric.
In 1908, Hermann Minkowski—once one of the math professors of a young Einstein in Zürich—presented a geometric interpretation of special relativity that fused time and the three spatial dimensions of space into a single four-dimensional continuum now known as Minkowski space. A key feature of this interpretation is the definition of a spacetime interval that combines distance and time. Although measurements of distance and time between events differ for measurements made in different reference frames, the spacetime interval is independent of the inertial frame of reference in which they are recorded.
Minkowski's geometric interpretation of relativity was to prove vital to Einstein's development of his 1915 general theory of relativity, wherein he showed how mass and energy curve this flat spacetime to a Pseudo Riemannian manifold.
A further elaboration
Four-dimensional Euclidean spacetime[edit]
See also: Four-dimensional space
In 1905–06 Henri Poincaré showed[4] that by taking time to be an imaginary fourth spacetime coordinate ict, where c is the speed of light and i is the imaginary unit, a Lorentz transformation can formally be regarded as a rotation of coordinates in a four-dimensional space with three real coordinates representing space, and one imaginary coordinate representing time, as the fourth dimension.
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Minkowski's principal tool is the Minkowski diagram, and he uses it to define concepts and demonstrate properties of Lorentz transformations (e.g. proper time and length contraction) and to provide geometrical interpretation to the generalization of Newtonian mechanics to relativistic mechanics.
The formal definition of proper time involves describing the path through spacetime that represents a clock, observer, or test particle, and the metric structure of that spacetime. Proper time is the pseudo-Riemannian arc length of world lines in four-dimensional spacetime. From the mathematical point of view, coordinate time is assumed to be predefined and we require an expression for proper time as a function of coordinate time. From the experimental point of view, proper time is what is measured experimentally and then coordinate time is calculated from the proper time of some inertial clocks.
So then coordinate time defines time when stationary relative to the local metric it would appear while proper time is time experienced which distorts ones view of the metric.
For a twin "paradox" scenario, let there be an observer A who moves between the A-coordinates (0,0,0,0) and (10 years, 0, 0, 0) inertially. This means that A stays at {\displaystyle x=y=z=0} x=y=z=0 for 10 years of A-coordinate time. The proper time interval for A between the two events is then
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So being "at rest" in a special relativity coordinate system means that proper time and coordinate time are the same.
Going back to a vertical ict vector with respect to the horizontal local metric and simplifying for a 2d space with time as the 3rd axis (giving layers of space in time?). It looks as if when one is moving, one then has a tilt in angle of the ict vector with respect to the plane of the local horizontal metric which has a coordinate time used to get the proper time of events for a moving observer.
It seems the idea of general relativity can be extended to this metric by creating a dip or well in the metric. Any object not moving in the metric still has a vertical ict vector, but in the gravity well it is now at an angle with the local metric. It seems this angle of the ict vector with respect to the local metric either simulates having velocity with respect to the metric, slowing time, or just having an angle w.r.t. it slowing time.
So then being at rest on a gravitational object at rest, one having a vertical ict vector with respect to the tilted metric then has slow time where as an object freely falling into the the gravity well speeding up has a faster clock? Not sure this makes complete sense as this gives some strange effects for living on a highly relativistic gravity well it would seem. (i.e. having a tilted ict vector with respect to a gravity well. -effects on magnetic fields measured on earth perhaps? - their experiment measuring an electric field from a magnetic field in the lab frame?)
Orbiting clocks have a dual time slowing effect. Their tilted ict vector or velocity with respect to the local metric radially and their angular velocity causing further ict angle tilt.
Some of the concepts seem very close to suggesting having actual velocity with coordinate time and space or is this just my misinterpretation?
The description of https://en.wikipedia.org/wiki/Proper_time The twin "paradox" "So being "at rest" in a special relativity coordinate system means that proper time and coordinate time are the same." I mean where they suggest experimental measurements can determine proper time to derive the coordinate time seems quite suggestive.
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Has there been any progress toward even possibly sending an FTL signal regardless of paradoxes or causality?
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BSu, it has been stated in the other thread you started, and discussion can continue there if you want, but for the record in this thread: No. There are no FTL technologies of any sort compatible with known physics. Any hypothetical things you hear about FTL involve things that to the best of our knowledge don't exist and there is no way to create.
Dustinthewind, I meant to write a thorough response, but never got the time, so here is a "short" one:
You seem to be confused between a metric and a representation of a metric. The metric itself in relativity does not depend on what frame you are viewing it from. To write down a metric in notation that you can do calculations with, you need to pick what coordinates to write it down in. An equivalent concept is vectors. You can do various math with vectors (say vectors that represent points on your computer screen) You can write down the differences between the locations of various points, or calculate the derivative of a moving point to get its velocity vector. To get the results in a numeric representation though, you need to pick a point on the screen to be the origin, and choose which direction is "x" and which direction is "y." The need to pick a coordinate system for final calculations does not mean that your choice is "special" in any way. Any choice works as long as you are consistent.
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BSu, it has been stated in the other thread you started, and discussion can continue there if you want, but for the record in this thread: No. There are no FTL technologies of any sort compatible with known physics. Any hypothetical things you hear about FTL involve things that to the best of our knowledge don't exist and there is no way to create.
Dustinthewind, I meant to write a thorough response, but never got the time, so here is a "short" one:
You seem to be confused between a metric and a representation of a metric. The metric itself in relativity does not depend on what frame you are viewing it from. To write down a metric in notation that you can do calculations with, you need to pick what coordinates to write it down in. An equivalent concept is vectors. You can do various math with vectors (say vectors that represent points on your computer screen) You can write down the differences between the locations of various points, or calculate the derivative of a moving point to get its velocity vector. To get the results in a numeric representation though, you need to pick a point on the screen to be the origin, and choose which direction is "x" and which direction is "y." The need to pick a coordinate system for final calculations does not mean that your choice is "special" in any way. Any choice works as long as you are consistent.
Thanks meberbs. I guess when I was suggesting a metric I was thinking of an actual structure to the vacuum. Something like quantum loop gravity where the structure of the vacuum has a quantized volume as do solid objects.
https://en.wikipedia.org/wiki/Loop_quantum_gravity
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meberbs, here is a mental challenge for you:
Lets imagine that FTL travel has been proven to be possible, with 100% solid experimental results. We can do FTL jumps to any XYZ coordinates in the Universe. They are instantaneous, preserve our momentum (+/frame of reference) and do not produce time-travel paradoxes.
Scientists around the world are trying to figure the math behind it, namely, what they got wrong before, thinking there would be time-paradoxes. You are one of them, lets hear how you would fix the math.
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meberbs, here is a mental challenge for you:
Lets imagine that FTL travel has been proven to be possible, with 100% solid experimental results. We can do FTL jumps to any XYZ coordinates in the Universe. They are instantaneous, preserve our momentum (+/frame of reference) and do not produce time-travel paradoxes.
Scientists around the world are trying to figure the math behind it, namely, what they got wrong before, thinking there would be time-paradoxes. You are one of them, lets hear how you would fix the math.
Personally, I'm not a strong believer in the weirder interpretations of superluminal phenomena. Yeah, I'm just an ignorant person on the Internet that knows nothing of relativity and physics.
But nevertheless, inferring that going FTL would take us to the past strikes me as an example of taking math too far.
If such a thing proves possible, we will probably learn that our models break at some point and new realities emerge.
We simply don't have enough examples (zero, probably) as of today for telling what would happen.
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meberbs, here is a mental challenge for you:
Lets imagine that FTL travel has been proven to be possible, with 100% solid experimental results. We can do FTL jumps to any XYZ coordinates in the Universe. They are instantaneous, preserve our momentum (+/frame of reference) and do not produce time-travel paradoxes.
Scientists around the world are trying to figure the math behind it, namely, what they got wrong before, thinking there would be time-paradoxes. You are one of them, lets hear how you would fix the math.
Simple, there are 3 possibilities, which have already been discussed in this thread, and which one would be evident from the experimental data:
1. Time travel is possible
2. There exists a fixed universal reference frame that all FTL travel is relative to. (causality holds because you can't do an FTL jump backwards in time in this frame.)
3. It has been suggested that wormhole type FTL could have a condition where any configuration of wormholes with a potential time loop would cause the wormholes to collapse. It is not obvious if this is actually a looser condition than #2, (it is at worst equivalent) since it is complicated to work out for the arbitrary number of wormholes case, and I suspect you could create a time travelling communication method by opening a small wormhole and seeing if it collapses.
Just about anything else wouldn't work because it would directly contradict experimental data that already exists in the real world.
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Scientists around the world are trying to figure the math behind it, namely, what they got wrong before, thinking there would be time-paradoxes. You are one of them, lets hear how you would fix the math.
Hi kamill85, look at the first post. I have edited a sort of index of later quotes into there. I can't remember if I included the wormhole idea though.
(edit: apparently not, but it is in the second post)
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meberbs, here is a mental challenge for you:
Lets imagine that FTL travel has been proven to be possible, with 100% solid experimental results. We can do FTL jumps to any XYZ coordinates in the Universe. They are instantaneous, preserve our momentum (+/frame of reference) and do not produce time-travel paradoxes.
Scientists around the world are trying to figure the math behind it, namely, what they got wrong before, thinking there would be time-paradoxes. You are one of them, lets hear how you would fix the math.
Personally, I'm not a strong believer in the weirder interpretations of superluminal phenomena. Yeah, I'm just an ignorant person on the Internet that knows nothing of relativity and physics.
But nevertheless, inferring that going FTL would take us to the past strikes me as an example of taking math too far.
If such a thing proves possible, we will probably learn that our models break at some point and new realities emerge.
That's like people in the 15th century admitting they don't know about math and physics but saying they don't believe the Earth goes round the sun.
The conclusions you come to just thinking about it without understanding what others have learned are not valid conclusions.
We simply don't have enough examples (zero, probably) as of today for telling what would happen.
That's not a valid conclusion.
Just because we haven't seen something doesn't mean we can't make conclusions about it, if we have a theory that fits a large body of evidence and that evidence can predict what would happen. That's how we knew what would happen when we set off an atomic bomb before we had ever seen one.
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I thought the current thinking was that there are no FTL paradoxes, as new parallel universes are created.
You may be able to go back in time and think you have killed your grandfather, but it will only be in your universe. Your original grandfather will be untouched.
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I thought the current thinking was that there are no FTL paradoxes, as new parallel universes are created.
You may be able to go back in time and think you have killed your grandfather, but it will only be in your universe. Your original grandfather will be untouched.
There was some discussion of that possibility in this thread somewhere.
It never seemed satisfactory because the result seemed to be a universe where the people who enter FTL and the people who exit it have no clear relationship to each other. Sometimes they just vanish. Sometimes people appear who have no history... and EVERY combination in between.
It could be an interesting SF scenario.. a universe where FTL changes other people but never yourself.. but it could not be defined well enough to include as a solution IMO
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I found this research paper
https://scholar.google.com/scholar?cluster=3548262082901723021&hl=en&as_sdt=0,14
Dynamical 3-Space: neo-Lorentz Relativity
Reginald T Cahill (Flinders University)
(Submitted on 5 Jul 2012)
There are some newer papers but not a lot of citations. However It seems to hit to spot for me in regards to what I was thinking about the structure of space time and the vacuum having a local velocity.
They mention the solution to the twin paradox, absolute clock slowing, velocity with respect to the CMB is indirectly referenced as having velocity at ~ 500km/s. Some other stuff mentioned. I haven't read all the newer stuff.
This goes along with my claim that I thought it was likely that a jump backward at near light speed wouldn't make one jump backward in time but that rather jumps were w.r.t. absolute space - Circumnavigating time paradoxes. That clocks might tick faster if sent to be at rest with respect to the CMB. That Lorentz contraction had something to do with motion w.r.t. the vacuum ect. Motion w.r.t. the CMB. That it fixes the twin paradox ect.
I think it also suggests the clock of an object flying toward a gravitational object should speed up and the clock of an object should slow down when flying away from a gravitational object. Also predicts for lens thiring effect (or frame dragging) where the speed of light is faster around in one direction than the other for large rotating objects. Or going around in one direction speeds up the clock more than going the other direction.
I.e. gravity and gravito magnetism via curvature induces an effective relative velocity on the vacuum or space time.
The gamma factor of special relativity can also be thought to be a geometric description of local velocity with respect to space time. Also why satellites clocks are slowed down not only by the gravitational potential they exist in but also their angular velocity which have separate velocity components which are perpendicular to each other.