Any resolutions to FTL paradoxes?

[WarpTech]

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,  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(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

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

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/, 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, 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, May 2005. (Last Accessed, 16, July 2016)

[KelvinZero]

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.

[meberbs]

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.

[WarpTech]

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.

[Bob012345]

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.

[KelvinZero]

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.

[scienceguy]

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?

[KelvinZero]

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.

[missinglink]

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

[KelvinZero]

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.

[meberbs]

I found this. I can't really make heads or tails out of it yet.

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.

[Norm38]

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.

[KelvinZero]

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.

[Norm38]

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.

[meberbs]

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.

[Norm38]

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.

[meberbs]

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

[Bob012345]

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.

[Norm38]

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.

[Norm38]

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.