Aether theories which are experimentally indistinguishable from SR.

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The discussion centers on the existence of aether theories that are experimentally indistinguishable from Special Relativity (SR). John Baez highlights that current experiments impose strict constraints, necessitating any aether theory to align closely with SR predictions, particularly regarding the isotropy of light speed in inertial frames. Participants inquire about the publication sources for these theories, specifically referencing Selleri's transformations, which purportedly offer alternative premises while yielding similar predictions to SR. The conversation also touches on various experiments and theoretical frameworks that challenge or explore the implications of light speed isotropy, emphasizing the need for further one-way tests to validate these theories. Overall, the discourse reflects ongoing interest and skepticism regarding the compatibility of aether theories with established relativistic principles.
  • #91
Apparently you did not (and still have not) read Pervects question.

His question was that if NIST defines the second, and the speed of light (and therefore the meter is a derived quantity), then what does it mean to measure the speed of light? The answer is that experimenters obviously do not use this definition when measuring the speed of light. Or are you saying you disagree with that statement?

clj4 said:
1. One way light speed cannot indeed be measured but two way can (and has been)
I have no clue what you are saying here. Even if you slipped and typed cannot instead of can, it still does not make sense.

Anyway, the point is that one way speeds cannot be specified in a coordinate independent manner. Thus experimenters must define what frames they are using when specifying the speed of light. The answer is that they use inertial frames (defined using SRs first postulate).

The question you ignored was:
Clj4, do you agree that GR allows us to use any coordinate systems and even the speed of light is not invarient when considering general coordinate transformations?

The question after this was:
Aether, do you understand that this does not mean SR is wrong, as SR is only applicable in inertial frames?

Aether agree that this is correct. (Repeated to remind others not to read too much into the fact that one way speeds cannot be defined in a coordinate independent manner.)
 
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  • #92
JustinLevy said:
Anyway, the point is that one way speeds cannot be specified in a coordinate independent manner. Thus experimenters must define what frames they are using when specifying the speed of light. The answer is that they use inertial frames (defined using SRs first postulate).

So what's your point ? You seem to repeat "Aether"'s phylosophical point that flies in the face of the Phys.Rev papers (11 of them).
What is with relentless repetition of "coordinate independent manner"? The whole discussion is about detecting one way light speed anisotropy. so I listed 11 papers that show how error bars for OWLS isotropy have been set. Are you reading the posts? See post 81 for a partial list. There are about 20 physicists that clearly disagree with the "philosophies" that you post. They disagree by using math and experiments. Can you make your point mathematically? Philosophy/literature means nothing. You would do well by reading at least some of the listed papers, especially the Gagnon, the CM Will and the A.Peters.

The question you ignored was:
Clj4, do you agree that GR allows us to use any coordinate systems and even the speed of light is not invarient when considering general coordinate transformations?

This is truly "non-sequitur". All the discussions so far have been in the SR framework, so what's with GR out of the blue?. This is one of the reasons why I ignored your post. The tone of the posts, the lack of any mathematical formalism and the "non-sequitur" content .
 
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  • #93
ZapperZ said:
Not in physics there isn't!

If this is YOUR belief from the very beginning, then you have dabbled in the wrong subject. And the fact that you have made a 180 degree turn from touting a series of "experimental evidence" to now claiming that you really don't need any experimental evidence means that you really have nothing to stand on, even with your Aether buddy who has disavowed your claims. You have also conviently ignored several pointed issues aimed directly at you.Zz.

What aether buddy, and to what post(s) are you referring?

Name an experiment that has measured one way isotrophy in free space - the references deal with Earth based measurements - they do not exclude the possibility that massive bodies condition local space (and I am not talking about entrainment or ether dragging) rendering the one way conclusions questionable on a global scale. This is yet unresolved .. further experimentation is needed to eliminate alternative theories.
 
  • #94
clj4 said:
So what\'s your point ? You seem to repeat \"Aether\"\'s phylosophical point that flies in the face of the Phys.Rev papers (11 of them).
It is not a philosophical point. It is a mathematical point. One way velocities cannot be specified in a coordinate independent manner.

The physical laws can be stated as tensor equations which are true in any coordinate system (inertial or not). The speed of light is not invarient to general coordinate transformations. This does not contradict the experiments which measure the speed of light, as they restrict themselves to inertial frames.

It you are having trouble with these concepts, feel free to start a new thread in the Mathematics / Tensor Analysis & Differential Geometry section of this forum.

clj4 said:
This is truly \"non-sequitur\". All the discussions so far have been in the SR framework, so what\'s with GR out of the blue?
It is not non-sequitur, as non-inertial frames have been brought up several times. This is part of the problem here, you are not listenning to other posters and therefore everyone is not even arguing about the same thing.

Special relativity has been tested and beautifully verified by experiment. This does not mean light speed is isotropic in all frames. It only means light speed is isotropic in inertial frames. You are claiming otherwise which is incorrect.


I do not understand why you are so hostile about this. The fact that coordinate systems exist in which the speed of light is anisotropic does NOT mean special relativity is wrong. And it definitely does not mean we need to admit some bizarre aether theory (and I wish Aether and others would stop claiming so).
 
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  • #95
yogi said:
What aether buddy, and to what post(s) are you referring?

Sorry, I mixed different posts with different people.

Name an experiment that has measured one way isotrophy in free space - the references deal with Earth based measurements - they do not exclude the possibility that massive bodies condition local space (and I am not talking about entrainment or ether dragging) rendering the one way conclusions questionable on a global scale. This is yet unresolved .. further experimentation is needed to eliminate alternative theories.

I don't need to name ANY experiment - you do! My response was for your dismissal of the need to have experimental evidence, or did you forget that you wrote THIS?

yogi said:
There is room for alternative spacetime formalisms w/i the totality of experimental results - conversing with mainstream thinkers can be most rewarding - not only because it provokes a more objective examination of ones own wrong ideas or personal pet theories or bias, but it also reveals that, although asserted with commanding authority, some of modern physics is not well grounded in ether theory or experiment.

If "modern physics" is wrong, it will be revealed NOT on a forum such as this, and certianly not by non-experts who aren't working deligently in the field! How do I know this? History! And it certainly would not be done without a clear understanding of both the theory and experiment.

Zz.
 
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  • #96
JustinLevy said:
The fact that coordinate systems exist in which the speed of light is anisotropic does NOT mean special relativity is wrong. And it definitely does not mean we need to admit some bizarre aether theory (and I wish Aether and others would stop claiming so).
Lorentz ether theory (aka, GGT, and modified Lorentz ether theory) is the same physical theory as SR but cast in an anisotropic coordinate system. Other than that, to what claim of mine are you referring?
 
  • #97
JustinLevy said:
It is not a philosophical point. It is a mathematical point. One way velocities cannot be specified in a coordinate independent manner.Special relativity has been tested and beautifully verified by experiment. This does not mean light speed is isotropic in all frames. It only means light speed is isotropic in inertial frames. You are claiming otherwise which is incorrect.
1. First off, you are clearly twisting my statements such that you are beating up on a strawman that you constructed.
2. Second off, the vast majority of the experiments that test SR are executed in the SLOWLY ROTATING frame of the Earth. This frame, while rotating has been treated as an INERTIAL frame for the last 120 years or so, starting with MMX. So, I suggest that you try arguing your point with the scores of experimenters that have proven SR to be correct. Try arguing with the 20 or so authors of the 11 papers that deal with setting the error bars on OWLS.

JustinLevy said:
The physical laws can be stated as tensor equations which are true in any coordinate system (inertial or not). The speed of light is not invarient to general coordinate transformations. This does not contradict the experiments which measure the speed of light, as they restrict themselves to inertial frames.

Good, we are not talking "general coordinate transformations". We are talking Mansouri-Sexl transforms (aka modified Lorentz transforms). This is what the test theories of SR (note there is no mention of GR) are. So why beat up on your strawman?
JustinLevy said:
I do not understand why you are so hostile about this. The fact that coordinate systems exist in which the speed of light is anisotropic does NOT mean special relativity is wrong. And it definitely does not mean we need to admit some bizarre aether theory (and I wish Aether and others would stop claiming so).

Good, we are in agreement here, the experiments quoted prove light speed to be isotropic and disprove the various "aether" theories.
 
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  • #98
Aether said:
Lorentz ether theory (aka, GGT, and modified Lorentz ether theory) is the same physical theory as SR but cast in an anisotropic coordinate system. Other than that, to what claim of mine are you referring?


Uh-oh, you "forgot" to mention that GGT assumes absoulute simultaneity.
 
  • #99
ZapperZ said:
Sorry, I mixed different posts with different people.

Thank You



I don't need to name ANY experiment - you do! My response was for your dismissal of the need to have experimental evidence, or did you forget that you wrote THIS?

.


If "modern physics" is wrong, it will be revealed NOT on a forum such as this, and certianly not by non-experts who aren't working deligently in the field! How do I know this? History! And it certainly would not be done without a clear understanding of both the theory and experiment.

Zz.

Perhaps you misinterpreted my post - I would like to see expirements that eliminate alternative explanations - for example, after Einstein introduced SR in 1905 there remained several other theories that satisfactorily explained the MMx results. Some of these theories were based solely on length contraction, others depended upon length contraction and time dilation. The Kennedy-Throndike experiment eliminated those theories based solely on the Fitzgerald contraction, but it left in-tact those based upon both length contraction and time dilation

Its been my experience that novel ideas are not always introduced by the diligent worker in the field. Its the unconventional thinker that goes outside the box - Many of the worlds great inventions come from persons who have recently been introduced to the problem - Now I don't say that this is true in most cases - but it is true in many. Nor does one have to have a complete understanding of another persons view of a theory in order to make contributions.
 
  • #100
I'm curious. Do you have a link, or something, about M-M apparatus in space?

Thanks
 
  • #101
clj4 said:
1. First off, you are clearly twisting my statements such that you are beating up on a strawman that you constructed.
I am not creating a strawman. If you feel I am misunderstanding your position, I appologize. But this is indeed how you are coming across.

You really do appear to be arguing that the speed of light is isotropic, no qualifications on the statement are necessary, period. This is not correct. You need to specify the coordinate system. The correct statement is that the speed of light is isotropic in all inertial frames.

For instance, even after specifically pointing out to you that velocities (even that of light) are a coordinate system dependent quantity, you wrote: Light speed is ISOTROPIC. One way light speed isotropy HAS BEEN successfully confirmed.


Also here, read what you just wrote in your previous post:

clj4 said:
Good, we are not talking \"general coordinate transformations\". We are talking Mansouri-Sexl transforms (aka modified Lorentz transforms). This is what the test theories of SR (note there is no mention of GR) are. So why beat up on your strawman?

We are not talking about completely general coordinate transformations, but the Mansouri-Sexl transforms are quite general and describe many non-inertial frames as well.

So my point is quite relevant:
The physical laws can be stated as tensor equations which are true in any coordinate system (inertial or not). The speed of light is not invarient to general coordinate transformations.


If you feel I am misunderstanding your position, please help clarify it.
It is obvious we agree SR is correct. And I assume we also agree that experiment constrains the transformations between inertial frames to be that of lorentz transformations. Here is where we seem to disagree:

- Experiments do NOT restrict what coordinate systems we can describe the universe with, because the physical laws can be stated as tensor equations which are true in any coordinate system. Do you agree? I hope so.

- If you modify the lorentz transformations, the speed of light will not necessarily be constant or isotropic in these new coordinate systems. And yes, of course the tensor equations of the physical laws will still be correct in these coordinate systems. Do you agree? I hope so.


If we already agree on these, great. I hope this has just been a misunderstanding of each other and we can move on.

As an added note for others: Just because modern formulations of physics allow the use of any coordinate systems, and just because we can only say that the speed of light is constant and isotropic in inertial frames, this in no way means aether theories should be entertained (because removing SR would require many many adhoc additions).
 
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  • #102
JustinLevy said:
Just because modern formulations of physics allow the use of any coordinate systems, and just because we can only say that the speed of light is constant and isotropic in inertial frames, this in no way means aether theories should be entertained (because removing SR would require many many adhoc additions).

Fine, we are done. There was never any discussion about non-inertial frames. The discussion was (see the title of the thread) about the separation beween Mansouri-Sexl theories and SR. In the MS thory, there is an infinite number of iINERTIAL frames in which light speed is not isotropic. This went over 300 posts over 3 or 4 threads with Aether. The OWLS experiments I cited, exploit this feature in separating MS from SR.
 
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  • #103
JustinLevy said:
As an added note for others: Just because modern formulations of physics allow the use of any coordinate systems, and just because we can only say that the speed of light is constant and isotropic in inertial frames, this in no way means aether theories should be entertained (because removing SR would require many many adhoc additions).
It does mean that one may not claim that all aether theories are ruled out by experiment, and that one may not claim that the one-way speed of light is measurable in any coordinate-system independent way. If an aether theory is presented with nothing more than adhoc additions to SR, then you may criticize it for this.
 
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  • #104
clj4 said:
Fine, we are done. There was never any discussion about non-inertial frames.
That's what you don't get. An inertial frame is defined as a coordinate system in which the one-way speed of light (all speeds/momentum actually) is isotropic.
 
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  • #105
Aether said:
That's what you don't get. An inertial frame is defined as a coordinate system in which the one-way speed of light (all speeds/momentum actually) is isotropic.

Really? What about the infinity of non-preferentail inertial frames in the Mansouri-Sexl theory? Last I checked , light speed was not isotropic in ANY of them, just in the preferentail frame. And they all are inertial...

Going around in circles again, Aether. Happy flying, make sure that you don't get dizzy. At the end of the flight, don't forget : aether theories are NOT indistinguishable from SR. The OWLS experiments and the theory behind them tell them apart. This is the point you "took off". This is the point where you also land.
 
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  • #106
Aether said:
It does mean that one may not claim that all aether theories are ruled out by experiment, and that one may not claim that the one-way speed of light is measurable in any coordinate-system independent way. If an aether theory is presented with nothing more than adhoc additions to SR, then you may criticize it for this.
Nonsense, you have been shown the opposite over 4 threads and more than 400 posts.
 
  • #107
clj4 said:
Really? What about the infinity of non-preferentail inertial frames in the Mansouri-Sexl theory? Last I checked , light speed was not isotropic in ANY of them, just in the preferentail frame. And they all are inertial...
Where in Mansouri-Sexl do they call a frame "inertial" that doesn't have an isotropic light speed?

Going around in circles again, Aether. Happy flying, make sure that you don't get dizzy. At the end of the flight, don't forget : aether theories are NOT indistinguishable from SR. The OWLS experiments and the theory behind them tell them apart. This is the point you "took off". This is the point where you also land.
No, this is me going around in circles again (I'm the one on the near-side holding the camera out the "window"). :biggrin:
 
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  • #108
Aether said:
Where in Mansouri-Sexl do they call a frame "inertial" that doesn't have an isotropic light speed?
Re-read the Mansouri papers,you have them, you obviously missed it. And to think that I wasted hundreds of posts with you.
 
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  • #109
clj4 said:
Aether said:
Where in Mansouri-Sexl do they call a frame "inertial" that doesn't have an isotropic light speed?
Re-read the Mansouri papers,you have them, you obviously missed it. And to think that I wasted hundreds of posts with you.
Quit stalling and answer the question.
 
  • #110
Paulanddiw said:
I'm curious. Do you have a link, or something, about M-M apparatus in space?

Thanks

Sorry - I do not.. was hoping myself that someone would soon undertake to refine Olaf Romers techniques to establish some anisotropic error bars on the measurement of light speed when the Earth is approaching and receding from Jupiter. Shapiro has drawn some conclusions about the isotrophy of radar signals bounced off planets, but not everyone agrees with his interpretation of the data. Seems it would be feasible to place a mirror and precision clock on a deep space probe that is receding from the solar system and measure the two way and one way light travel times...
 
  • #111
Paulanddiw said:
I'm curious. Do you have a link, or something, about M-M apparatus in space?

Thanks
Try this: http://lisa.jpl.nasa.gov/TECHNOLOGY/LISA_interfer.html

yogi said:
Seems it would be feasible to place a mirror and precision clock on a deep space probe that is receding from the solar system and measure the two way and one way light travel times...
This clock would have to be synchronized with some other clock; typically either by Einstein's procedure or by slow clock transport. This makes any one-way light travel time "measurement" coordinate-system dependent. It's less confusing to talk about the results of such an experiment in terms of the coordinate-system independent \alpha parameter of Mansouri-Sexl theory.
 
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  • #112
wisp said:
Thanks for the links. I will study this fully, but I can see things are not right from the start. From “Why the Ether is Unobservable” dated November 21, 1999:



This opening paragraph is a bit controversial, suggesting that there is no proof of the ether, when there is real evidence to suggest that the detection of the ether is possible, the latest example being the Dewitte experiment.

There is absolutely nothing controversial about saying that the ether is unobservable from the perspective of mainstream science.

The fact that it is "controverisal" from your perspective says volumes about your perspective to anyone who is in the slightest bit familiar with mainstream physics.

The Dewitte experiments have failed the most important principle of science - reproducibility. Irreproducible results are worthless, and there have been many unsucessful attempts to reproduce the Dewitte results that you apparently cling to. Unless and until these results can be reliably and repeatably reproduced, they do not and cannot prove anything, except that experimenters can make mistakes, which any reasonable person already knows.

There have been some recent suggestions that, possibly, the Dewitte results MIGHT be able to be reproduced with a setup that involved deliberately putting gas into the interferometer. Frankly, I don't think that this is a very likely. It's the sort of "forlorn hope" that anyone who wants to be an ether theorist (for whatever personal reasons they may have for this desire) have to rest their hats on nowadays, as anything that's significantly more likely has already been ruled out by numerous experiments.
 
  • #113
Aether said:
Quit stalling and answer the question.
This is not France, Joseph. Where you live you can order your servants.
Re-read your papers.
 
  • #114
clj4 said:
This is not France, Joseph. Where you live you can order your servants.
Re-read your papers.
You have made an absurdly false claim about what's in the Mansouri-Sexl papers, so I demand that you answer my question. Otherwise, your claim is forfeit. So, quit stalling and answer the question.
 
  • #115
Aether said:
You have made an absurdly false claim about what's in the Mansouri-Sexl papers, so I demand that you answer my question. Otherwise, your claim is forfeit. So, quit stalling and answer the question.

You asked for it, frenchie, here it is:

1. Read page 500 of the Mansouri paper at the bottom,
the definition of the preferred frame \Sigma.

2. Read the Tom Roberts page, you know, the one that you quoted so fondly when it supported your POV re: indistiguishability of "aether" theories from SR.

3. And read this:

https://www.physicsforums.com/showpost.php?p=755432&postcount=92

..your own words! Once in a while, under proper supervision you can even do simple calculations correctly. Not very often.

If you still don't get it go get another degree from Sorbonne in how to argue endlessly by cheating and by diversion.
 
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  • #116
pervect said:
The Dewitte experiments have failed the most important principle of science - reproducibility. Irreproducible results are worthless, and there have been many unsucessful attempts to reproduce the Dewitte results that you apparently cling to. Unless and until these results can be reliably and repeatably reproduced, they do not and cannot prove anything, except that experimenters can make mistakes, which any reasonable person already knows.
I think this
http://prola.aps.org/abstract/PRD/v42/i2/p731_1?qid=6c4ab66eee46e0e8&...
was conceptually similar.

IIRC it used hydrogen-maser clocks separated by about 10miles of fiber optic cable. It produced much the same signal that Dewitte shows, but they only ran for a few days.

I'm inclined to think its a replication.
Didn't really have much use for Dewitte's ideas about it though.
Gotta say he was nice enough to send me his raw date though.
 
  • #117
clj4 said:
You asked for it, frenchie, here it is:

1. Read page 500 of the Mansouri paper at the bottom,
the definition of the preferred frame \Sigma.

2. Read the Tom Roberts page, you know, the one that you quoted so fondly when it supported your POV re: indistiguishability of "aether" theories from SR.

3. And read this:

https://www.physicsforums.com/showpost.php?p=755432&postcount=92

..your own words! Once in a while, under proper supervision you can even do simple calculations correctly. Not very often.

If you still don't get it go get another degree from Sorbonne in how to argue endlessly by cheating and by diversion.
I looked at your refs 1&3, but found nothing whatsoever suggesting that the one-way speed of light is anisotropic in any inertial frame; ref 2 is too non-specific. Please quote the actual passages that you are referring to. Also, please control your temper (and your paranoia); I don't want to see you banned from PF.
 
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  • #118
Aether said:
I looked at your refs 1&3, but found nothing whatsoever suggesting that the one-way speed of light is anisotropic in any inertial frame; ref 2 is too non-specific. Please quote the actual passages that you are referring to. Also, please control your temper (and your paranoia); I don't want to see you banned from PF.

Actually, you'd love to see me banned but is not going to happen as long as I expose your false claims. Can't you read your own posts? Your own calculations (which happen for once to be right)?
No? read again:

https://www.physicsforums.com/showpost.php?p=755432&postcount=92Still can't read?

Try this one:

C. Braxmaier, H. Müller, O. Pradl, J. Mlynek, A. Peters, and S. Schiller: "New Tests of Relativity Using a Cryogenic Optical Resonator", Phys. Rev. Lett. 88, 010401 (2002).

You can find it (together with a lot of others that say the same thing) here:

http://qom.physik.hu-berlin.de/

(under "Publications")
 
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  • #119
clj4 said:
Actually, you'd love to see me banned but is not going to happen as long as I expose your false claims.

Can't you read your own posts? Your own calculations (which happen for once to be right)?
No? read again:

https://www.physicsforums.com/showpost.php?p=755432&postcount=92


Still can't read?

Try this one:

C. Braxmaier, H. Müller, O. Pradl, J. Mlynek, A. Peters, and S. Schiller: "New Tests of Relativity Using a Cryogenic Optical Resonator", Phys. Rev. Lett. 88, 010401 (2002).

You can find it (together with a lot of others that say the same thing) here:

http://qom.physik.hu-berlin.de/

(under "Ppublications")
Please quote the specific passages that support your claim, or your claim stands forfeit.
 

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