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#1680 by Rodal on 17 Sep, 2017 16:39
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This picture as drawn in the Wikipedia article violates conservation of momentum, will not get the center of mass to accelerate according to what is just shown on this picture.
Many things in the article in Wikipedia are incorrect.
Will not elaborate further since this is not the appropriate place
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#1681 by Mulletron on 17 Sep, 2017 16:54
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This picture as drawn in the Wikipedia article violates conservation of momentum, will not get the center of mass to accelerate according to what is just shown on this picture.
Many things in the article in Wikipedia are incorrect.
Will not elaborate further since this is not the appropriate place
Please elaborate further. They work the same way anyway. The drawing is missing the damping element of the design. -
#1682 by Bob012345 on 17 Sep, 2017 17:27
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Sorry folks. I'm not seeing the EM drive in all this loose, just a hijacked topic.
Which can be easily addressed by you (or someone else) posting something on EM Drive - related to space flight applications. Posting is the best way to bring the thread back on focus
The above discussions are peripherally related to the subject as follows: there have been posts conjecturing whether the EM Drive can be explained by gravitational waves, or by General Relativity or by super-Machian effects not present in General Relativity.
Many people are still wondering: how can something like the EM Drive accelerate the center of mass?
The thread naturally gyrated to some fundamental issues, because these fundamental issues are not resolved -as excellently documented by flux_capacitor-
Yeah, in a weird way, I'm interested in all this black hole entropy stuff, and similar research I'm doing on the side, because I think I convinced myself the other day that an EMdrive must be allowed a way to have an exhaust, as in only a portion of the energy in the system can be converted to thrust, and the rest must be able to escape.
If the force on the EmDrive can be considered external and long range, the overall momentum is balanced elsewhere in the universe and you wouldn't see it locally. You really wouldn't care since the local system is under an external force and local momentum is not conserved but universally it is. I think it's important to consider that until they are fully understood, the EmDrive or the Mach effect thrusters may be either a local effect or in effect an external force. -
#1683 by Bob012345 on 17 Sep, 2017 17:37
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This picture as drawn in the Wikipedia article violates conservation of momentum, will not get the center of mass to accelerate according to what is just shown on this picture.
Many things in the article in Wikipedia are incorrect.
Will not elaborate further since this is not the appropriate place
Please elaborate then in the Woodward effect thread. Is it necessity of acceleration that's missing? Thanks. The picture implies just interchanging the masses would work. That's basically a Dean Drive. -
#1684 by meberbs on 17 Sep, 2017 17:37
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1) Any matter creates a distortion in spacetime. If that matter was traveling near c, but its distortion could only travel at c there would be a bow wave and wake of spacetime distortion. (note: some warpdrive theories try to turn this around to push spacecraft) The moving matter would essentially be constantly climbing out of its own "gravity well", which would require constant acceleration to maintain velocity. As no acceleration is present, all moving objects would be subject to their own distortion drag and come to a halt like a ship without power.
One of the most basic principles of relativity is that all inertial reference frames are equivalent. This means that while one observer will see that matter as travelling near c, another would see it stationary, and another would see it travelling near c in a different direction. They all have to see the same result, so it does not makes sense for there to be drag in the direction of motion, because it can't be agreed upon what direction it is moving. The gravitational field of a moving object is related to its velocity, so no energy draining bow shock is required unless acceleration is involved.2) This would also be true of rotating bodies. The outer matter of a planet would be subject to its own drag more than the inner matter, slowing rotation and inducing mechanical stress. Similarly, planets in orbit would slow from their own drag if the spacetime distortion was any velocity other than instantaneous.
There is in fact drag in orbital systems (due to the acceleration involved producing gravity waves, as I said before there is not drag due to constant velocity). Section III of thiscalculates the inspiral due to gravitational waves, which is mostly significant for things like binary star systems, and has been observed.
There are also frame dragging effects by rotating bodies predicted by GR and measured by experiments like Gravity Probe B.2) This would 3) In three-body problems, like the Sun-Earth-Moon, each time the moon was in front of the earth's direction it's spacetime distortion would be closer to the earth's center of mass as the moon would be orbitting the trailing distortion of the earth.
Did you not read the link I put in my last post? The gravitational field of a moving body is such that the orbit is not around the retarded position of the object. Accelerations present in the system such as due to orbiting the sun do have some effects.
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#1685 by Rodal on 17 Sep, 2017 18:05
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Thank you for the excellent link to Laplace's mistake.2) This would 3) In three-body problems, like the Sun-Earth-Moon, each time the moon was in front of the earth's direction it's spacetime distortion would be closer to the earth's center of mass as the moon would be orbitting the trailing distortion of the earth.
Did you not read the link I put in my last post? The gravitational field of a moving body is such that the orbit is not around the retarded position of the object. Accelerations present in the system such as due to orbiting the sun do have some effects.
As a different topic dealing with time delays a very interesting effect found in gravitational waves are hereditary terms dependent on the full past history of the source. The effect is really one of fading memory predominantly sensitive to the recent past evolution of the system and only negligibly dependent on its very remote past history. Although quite small (4PN) in absolute magnitude, is rather large relative to the usual damping force radiation.
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.37.1410 -
#1686 by Mulletron on 17 Sep, 2017 21:26
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I think I've got the concept nailed down but there's a HUGE problem. If this is gravitational in nature, as has been pointed out by Rodal, and I fully agree with him, the effect is too weak to be predicted by conventional theory. Spacetime is very stiff, orders of magnitude stiffer than any material substance, like a steel beam. Either the EMdrive is really doing something that is stronger than it should be or there's a problem with the coupling coefficient. I propose the following thought experiment, spoken in colloquial terms.
A length of spacetime, as in a finite length of flat space, say from point a to point b, must have a natural resonant frequency. It's stiff and supports the propagation of waves, so it must. I'll treat it as if it is an extremely stiff rod of length l.
So you guys have all seen the bowling ball on a rubber sheet analogy. It's not accurate but does a good job of communicating the general concept of bending of space and time intuitively.
Well I'm going to give it to you again, differently. Those of you who have jumped on a trampoline will know what I'm talking about. So standing still in the center of a trampoline is analogous to the rubber sheet visualization we all love (or not). Standing there, you bend the surface down maybe a few inches, it depends on how stiff the trampoline is and your mass. But get jumping at just the right frequency and you can make the trampoline bend almost to the ground. Get two people on there and you time it just right and one person can get a super bounce while the other person falls flat (that will take your legs out if you're not ready for it).
The physical realization of such a resonant motion in spacetime would be the induction of a gravitational field by the alternating increase and decrease of gravitomagnetic flux, on the left side is an oscillating g. We know how weak this is, very very weak, but it isn't zero. The most important factor is doing so is finding the correct period of oscillation. You have to do this in two (TE012) or more (like TE013) different, but causally connected places, with the addition of a deliberate method of dissipation at one end that is greater with respect to the other end. We don't want a standing oscillation. The goal is to create a partial standing wave in spacetime itself. What's happening in the cavity is mirrored in spacetime.
I ask myself, if I have a stiff unyielding medium, how do I get it to bend? Do I use brute force? That's one way. Do I have access to enough energy to wield such a monumental brute force? Like as much as a planet? No. A better way is to hit it, over and over again, with attainable amounts of energy, and at the right frequency, so that it is forced to yield by its own harmonic motion.
A little humor here. How do I get an 800 pound gorilla to have fun on a swing set? I can hardly push em! I push him only slightly, only slightly, and I time it just right. That'll get him going. A fun day at the park.
Explore the dependence of d phi/dt @28:56.
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#1687 by Propylox on 17 Sep, 2017 22:20
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Well, there's a sure fire way to check.-snip- No, I'm saying no new science or violation of existing science is needed to describe the observations. There's plenty of theories about what's happening, but my money's on it being an exceedingly inefficient electron gun.
-snip- There are plenty of ways for the result through now to be explained by experimental errors, however I do not see how it could be functioning as an electron gun.
With the intense electromagnetic fields being created, I doubt a Faraday cup could distinguish slight electron expulsion (note; I didn't say "emission" as the local field created once the cavity becomes harmonic is considerably stronger than that required for emission) from all the other equipment's emissions. Time to bust out the phosphor screen and see if anything hits it, or strikes that theory.
Nope, just pointing out mistakes happen. Einstein set a speed limit of c and refuted the notion of anything exceeding it, perhaps because he didn't consider pure energy cannot exist in the Universe without a mass-carrier and the smallest mass(less object?) he knew was a photon. Though particle-wave duality, or energy confined to time vs creating a ripple in it, should have clued him in.Einstein considered anything faster than his speed limit of c as unacceptable. But regardless, the effects of "gravity" and the observation of "gravity waves" remains instantaneous ...
Completely untrue, and it seems as if you are trying to claim that you are smarter than Einstein. It is not just Einstein, but everyone physicist who understands relativity realizes that any kind of information including gravity travelling faster than light results in time travel paradoxes.
Years later when presented with quantum entanglement - instantaneous action at distance as energy interacts with mass - Einstein did not refute it or explain how his speed limit didn't apply, but called it "spooky" (as I previously mentioned, "magic, etherial or ghostly" describe one's ignorance of science) -
#1688 by M.LeBel on 18 Sep, 2017 00:53
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...In (1) Sakharov disproved Hawking, who previously claimed (before they met in 1987) that maximal entropy alone would reverse the arrow of time. Sakharov showed him he was wrong, as entropy grows with the arrow of time (both are related) and the time arrow can reverse only if entropy reaches a minimal state, i.e. zero value. ...
This is interesting Thanks for pointing this out.
While on the subject of gravity and entropy ...
Well, gravity and entropy are the same. Time runs slower as we get closer to the ground, yes? And an object moves spontaneously (fall) toward the ground, right? We could say that slower time pulls the object down ... ??
There is another way to approach this. The speed of light is constant everywhere, any frame of reference. As we get closer to the ground, the speed of light must remain constant. Let’s see. As time slows down the units seconds must be relatively longer. So, “space” must also get longer in order for the ratio meter/second to be constant. In other words, an object falling toward the ground is actually falling into larger space. Reminds you of something? Entropy is the spontaneous dispersal into a larger volume. And, because of the constancy of c, we can say as well “dispersion in time”.
Is this wrong, and why?
Marcel,
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#1689 by spupeng7 on 18 Sep, 2017 02:12
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For those readers who are struggling how the Mach Principle works here is a quick video on youtube that's easy to understand.
Thank you for the interesting video. Please note:
Shell
1) There is nothing discussed in this video about Mach's principle that is not fully contained in Einstein's General Relativity. So if Mach's principle makes one aware of something that is already present in Einstein's General Relativity, great!. However, there is no "extra-Machian" effect discussed in the video that is not already present in Einstein's General Relativity.
(...)
Nothing except that mass resists acceleration instantly. GR assumes that mass resists acceleration because it is mass, which is a circular argument based on faith. This could be wrong, if no other explanation for emdrive thrust is found, while it continues to be verified, then GR is an incomplete description of mechanics. -
#1690 by spupeng7 on 18 Sep, 2017 02:19
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...In (1) Sakharov disproved Hawking, who previously claimed (before they met in 1987) that maximal entropy alone would reverse the arrow of time. Sakharov showed him he was wrong, as entropy grows with the arrow of time (both are related) and the time arrow can reverse only if entropy reaches a minimal state, i.e. zero value. ...
This is interesting Thanks for pointing this out.
While on the subject of gravity and entropy ...
Well, gravity and entropy are the same. Time runs slower as we get closer to the ground, yes? And an object moves spontaneously (fall) toward the ground, right? We could say that slower time pulls the object down ... ??
There is another way to approach this. The speed of light is constant everywhere, any frame of reference. As we get closer to the ground, the speed of light must remain constant. Let’s see. As time slows down the units seconds must be relatively longer. So, “space” must also get longer in order for the ratio meter/second to be constant. In other words, an object falling toward the ground is actually falling into larger space. Reminds you of something? Entropy is the spontaneous dispersal into a larger volume. And, because of the constancy of c, we can say as well “dispersion in time”.
Is this wrong, and why?
Marcel,
Marcel,
please expand on this argument if you have time. I love that you think on how time dilation induces acceleration, it is a subject that warrants further consideration.
John.. -
#1691 by WarpTech on 18 Sep, 2017 04:25
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...In (1) Sakharov disproved Hawking, who previously claimed (before they met in 1987) that maximal entropy alone would reverse the arrow of time. Sakharov showed him he was wrong, as entropy grows with the arrow of time (both are related) and the time arrow can reverse only if entropy reaches a minimal state, i.e. zero value. ...
This is interesting Thanks for pointing this out.
While on the subject of gravity and entropy ...
Well, gravity and entropy are the same. Time runs slower as we get closer to the ground, yes? And an object moves spontaneously (fall) toward the ground, right? We could say that slower time pulls the object down ... ??
There is another way to approach this. The speed of light is constant everywhere, any frame of reference. As we get closer to the ground, the speed of light must remain constant. Let’s see. As time slows down the units seconds must be relatively longer. So, “space” must also get longer in order for the ratio meter/second to be constant. In other words, an object falling toward the ground is actually falling into larger space. Reminds you of something? Entropy is the spontaneous dispersal into a larger volume. And, because of the constancy of c, we can say as well “dispersion in time”.
Is this wrong, and why?
Marcel,
It is the contracted ruler that makes it appear space has stretched.
It is the slow clock that results in time dilation.
Quantum mechanically, both effects can arise from radiative damping due to stimulated emissions, which affect the length of the ruler and the rate of the clock.
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#1692 by Mulletron on 18 Sep, 2017 11:36
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This looks awfully familiar.
https://physics.stackexchange.com/questions/225264/conservation-of-linear-momentum-and-velocity-of-a-system-damper-and-spring-in-a
I guess it pays to do your homework instead of having a knee-jerk reaction and immediately declaring something is impossible. -
#1693 by Rodal on 18 Sep, 2017 12:01
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Not a precise statement of Einstein's assumption. Instead Einstein assumed the equivalence principle.
Nothing except that mass resists acceleration instantly. GR assumes that mass resists acceleration because it is mass, which is a circular argument based on faith. This could be wrong, if no other explanation for emdrive thrust is found, while it continues to be verified, then GR is an incomplete description of mechanics.
"we [...] assume the complete physical equivalence of a gravitational field and a corresponding
acceleration of the reference system."
Not a circular argument.
Please let us know what experiments do you know of that have found a difference between gravitational mass and inertial mass.
http://iopscience.iop.org/article/10.1088/0264-9381/29/18/180301/meta
https://en.wikipedia.org/wiki/Equivalence_principle#Tests_of_the_weak_equivalence_principle
Please let us know what experiments you know of that have revealed a Machian effect not present in Einstein's General Relativity.
You also state: "mass resists acceleration instantly" please let us know what experiments do you know of that prove that mass resists acceleration instantly (superluminally : much faster than the speed of light) while gravitation travels at the speed of light (not instantly) -
#1694 by Gilbertdrive on 18 Sep, 2017 12:52
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Not a precise statement of Einstein's assumption. Instead Einstein assumed the equivalence principle.
Nothing except that mass resists acceleration instantly. GR assumes that mass resists acceleration because it is mass, which is a circular argument based on faith. This could be wrong, if no other explanation for emdrive thrust is found, while it continues to be verified, then GR is an incomplete description of mechanics.
"we [...] assume the complete physical equivalence of a gravitational field and a corresponding
acceleration of the reference system."
Not a circular argument.
Please let us know what experiments do you know of that have found a difference between gravitational mass and inertial mass.
http://iopscience.iop.org/article/10.1088/0264-9381/29/18/180301/meta
https://en.wikipedia.org/wiki/Equivalence_principle#Tests_of_the_weak_equivalence_principle
Please let us know of what experiment you know of that has revealed a Machian effect not present in Einstein's General Relativity.
You also state: "mass resists acceleration instantly" please let us know what experiments do you know of that prove that mass resists acceleration instantly (superluminally : much faster than the speed of light) while gravitation travels at the speed of light (not instantly)
If I understand correctly, it is not about the propagation of something, but about a local property, without any notion of distance involved.
What I am not sure to understand is what “resisting to acceleration” means. Maybe spupeng7 meant something like “Inertia law locally applies instantly to any modification due to a force of the trajectory of any material object ”
Spupeng7, please, can you give an explanation of what you meant exactly ? I am not sure of my understanding.
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#1695 by wavelet on 18 Sep, 2017 13:27
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Following a previous author search I found this paper the shows why gravitational mass and inertial mass have the same value for a given object or particle.
One is a gravitoelectric effect and the other is a gravitomagnetic effect in the presence of a model that includes coupled mass currents in a higher dimensional space or multiverse. Truly convoluted indeed, who knows?
http://www.chronos.msu.ru/old/EREPORTS/fontana_gravitation.pdf...
Not a precise statement of Einstein's assumption. Instead Einstein assumed the equivalence principle.
Nothing except that mass resists acceleration instantly. GR assumes that mass resists acceleration because it is mass, which is a circular argument based on faith. This could be wrong, if no other explanation for emdrive thrust is found, while it continues to be verified, then GR is an incomplete description of mechanics.
"we [...] assume the complete physical equivalence of a gravitational field and a corresponding
acceleration of the reference system."
Not a circular argument.
Please let us know what experiments do you know of that have found a difference between gravitational mass and inertial mass.
http://iopscience.iop.org/article/10.1088/0264-9381/29/18/180301/meta
https://en.wikipedia.org/wiki/Equivalence_principle#Tests_of_the_weak_equivalence_principle
Please let us know of what experiment you know of that has revealed a Machian effect not present in Einstein's General Relativity.
You also state: "mass resists acceleration instantly" please let us know what experiments do you know of that prove that mass resists acceleration instantly (superluminally : much faster than the speed of light) while gravitation travels at the speed of light (not instantly)
If I understand correctly, it is not about the propagation of something, but about a local property, without any notion of distance involved.
What I am not sure to understand is what “resisting to acceleration” means. Maybe spupeng7 meant something like “Inertia law locally applies instantly to any modification due to a force of the trajectory of any material object ”
Spupeng7, please, can you give an explanation of what you meant exactly ? I am not sure of my understanding. -
#1696 by OnlyMe on 18 Sep, 2017 14:40
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....
You also state: "mass resists acceleration instantly" please let us know what experiments do you know of that prove that mass resists acceleration instantly (superluminally : much faster than the speed of light) while gravitation travels at the speed of light (not instantly)
Stop for a moment. Think about what you are saying above.
The inertial restistance of mass to acceleration is not a property that propagates, even while it involves a change in the velocity of mass. In a sense it is a static reaction (that sounds messed up but...).
Show any experiment or even classical observation where there is any delay in an object's inertial resistance to a change in velocity. Since inertia appears from all experience to occur over infinitely small distances, even an instantaneous inertial resistance to acceleration, has nothing to do with velocities classical or superluminal.
Changes in velocity are restricted to speed of light limitations (theoretically), and realistic classical velocities as a matter of observation and experience.., but inertia exists with or without a change in velocity and thus exist without delay. An object's resistance to acceleration is instantaneous. If it were not, super luminal velocities would be possible over some undefined duration.., the instant before a light time delay....
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#1697 by Rodal on 18 Sep, 2017 14:47
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If I understand correctly, it is not about the propagation of something, but about a local property, without any notion of distance involved.
What I am not sure to understand is what “resisting to acceleration” means. Maybe spupeng7 meant something like “Inertia law locally applies instantly to any modification due to a force of the trajectory of any material object ”
Spupeng7, please, can you give an explanation of what you meant exactly ? I am not sure of my understanding....
Thank you for the interesting video. Please note:
1) There is nothing discussed in this video about Mach's principle that is not fully contained in Einstein's General Relativity. So if Mach's principle makes one aware of something that is already present in Einstein's General Relativity, great!. However, there is no "extra-Machian" effect discussed in the video that is not already present in Einstein's General Relativity.
(...)
Nothing except that mass resists acceleration instantly. ...
His post was in reference to the video on Mach's principle posted by SeeShell.
The word "instant" or "instantaneous" does not appear once in:
Brans (of Brans-Dicke fame) recent Expert Opinion article on "What is Mach's principle?" in Annalen der Physik http://onlinelibrary.wiley.com/doi/10.1002/andp.201100706/pdf
Wikipedia's article on Mach's principle
https://en.wikipedia.org/wiki/Mach%27s_principle
and most importantly, the vague book of Mach himself:
E. Mach "The Science of Mechanics" OpenCourt, translated by McCormack
https://www.amazon.com/Science-Mechanics-Critical-Historical-Development/dp/0875482023/ref=sr_1_2?ie=UTF8&qid=1505746398&sr=8-2&keywords=Ernst+Mach++Mechanics
where in p. 267 where Mach himself discusses what is now known as his principle...
Stop for a moment. Think about what you are saying above.
The inertial restistance of mass to acceleration is not a property that propagates, even while it involves a change in the velocity of mass....
Stop for a moment. Think about what you are discussing: posts about Mach's Principle that state that inertia is due to "the distant stars". I asked what was discussed in this video about Mach's principle that is not fully contained in Einstein's General Relativity, and this was answered by "Nothing except that mass resists acceleration instantly."
Then explain:
1) how do the "distant stars" in Mach's principle "resist [locally, here] acceleration instantly"
2) how does the explanation in #1 above differ from Einstein's General Relativity. What is needed that is not in Einstein's General Relativity?
3) experiments supporting explanation in #1 and #2 above -
#1698 by Gilbertdrive on 18 Sep, 2017 15:58
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Stop for a moment. Think about what you are discussing: posts about Mach's Principle that state that inertia is due to "the distant stars". I asked what was discussed in this video about Mach's principle that is not fully contained in Einstein's General Relativity, and this was answered by "Nothing except that mass resists acceleration instantly."
Then explain:
1) how do the "distant stars" in Mach's principle "resist [locally, here] acceleration instantly"
2) how does the explanation in #1 above differ from Einstein's General Relativity. What is needed that is not in Einstein's General Relativity?
3) experiments supporting explanation in #1 and #2 above
With the sense that I give to "resist locally instantly" it is already in GR.
If someone means that if all the distant stars disappear, it would propagate instantly to us, and that inertia would be affected instantly, it violates GR. -
#1699 by OnlyMe on 18 Sep, 2017 16:40
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.......
Stop for a moment. Think about what you are saying above.
The inertial restistance of mass to acceleration is not a property that propagates, even while it involves a change in the velocity of mass....
Stop for a moment. Think about what you are discussing: posts about Mach's Principle that state that inertia is due to "the distant stars". I asked what was discussed in this video about Mach's principle that is not fully contained in Einstein's General Relativity, and this was answered by "Nothing except that mass resists acceleration instantly."
Then explain:
1) how do the "distant stars" in Mach's principle "resist [locally, here] acceleration instantly"
2) how does the explanation in #1 above differ from Einstein's General Relativity. What is needed that is not in Einstein's General Relativity?
3) experiments supporting explanation in #1 and #2 above
First, I clip(ed) portions of (the) discussion(s) most often because I am responding to the specific portion of a post I quote. My response was not to the discussion as a whole. It was to the way your specific comment in bold seemed to come across. That said...
In #1 above, are you suggesting that Mach's principle can only be interpreted within the context of Mach's knowledge base at the time? Mach died just a year after GR was published and his ideas were formulated largely within a strict Newtonian context.
Interpreting Mach's principle within the context of our current understanding, the distant stars have a light time delayed affect on the curvature of spacetime locally. Any local change in the velocity (acceleration) of an object is instantaneously subject to that light time delayed affect.
Again being a bit redundant, Mach's principle was formulated within a Newtonian understanding of physics, while we know today that GR is a better description of gravitation. One difference being whether gravitation is an instantaneous force (Newtonian) or limited to propagation at the speed of light (Einstein and GR)
Maybe it is just a misunderstanding on my part, but when you place a comment in bold, it seems to place some independent significance on its content, apart from the discussion as a whole.
By separating the statement, "mass resists acceleration instantly" it seemed to make that statement the issue, rather than any flawed argument that led to it.
When I began my post with, " Stop for a moment. Think about what you are saying above.", my intent was to point out that it did not come across the way I am almost certain you intended.
But I guess I am guilty of being too focused on that specific quote.., out of the greater context of the discussion. Kind of like criticizing a quote from Mach out of the context of his knowledge base.
