Aether theories which are experimentally indistinguishable from SR.

[JustinLevy]

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:

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).

 

[clj4]

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.

 

[Aether]

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.

 

[Aether]

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.

 

[clj4]

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.

 

[clj4]

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.

 

[Aether]

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").

 

[clj4]

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.

 

[Aether]

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.

 

[yogi]

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...

 

[Aether]

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

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.

 

[pervect]

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.

 

[clj4]

Quit stalling and answer the question.

This is not France, Joseph. Where you live you can order your servants.
Re-read your papers.

 

[Aether]

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.

 

[clj4]

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.

 

[NoTime]

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.

 

[Aether]

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.

 

[clj4]

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")

 

[Aether]

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.

 

[clj4]

Please quote the specific passages that support your claim, or your claim stands forfeit.

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

Is this a french thing when you loose an argument you declare victory? Even when you defeat yourself? See here:

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

 

[Aether]

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

Is this a french thing when you loose an argument you declare victory? Even when you defeat yourself? See here:

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

There isn't anything in this post that supports your claim. I can't figure out what's confusing you unless you quote the specific passage to which you are referring.

 

[JustinLevy]

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.

We are not done because you are still not understanding.

Are you defining an inertial frame as a frame in which a freely moving object has a constant velocity (that is, the frame agrees with Newtons First Law)? This is the only way I can see anyone calling the frames of MS theory \"inertial frames\".

First of all, note that is not the relativistic definition of an inertial frame.

But if you wish to use that definition, so be it.
You have admitted that there are coordinate systems in which light speed is not isotropic. Good, it appears we are now in agreement that the speed of light is not a coordinate system independent quantity.

So that answers one of my questions and leaves this one:

-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.


The point you are missing is that these one way light experiments only measure the one way speed of light IN INERTIAL FRAMES (defined by the first postulate of SR ... not the second one as Aether claims ... and not with what Clj4 is apparrently using as a definition of inertial frames). The experiments cannot say more about the one-way speed of light than this because it is a coordinate system dependent quantity. The experiments agree with SR beautifully, so the one-way speed of light is constant and isotropic IN INERTIAL FRAMES.

 

[yogi]

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

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.

If the intent of the experiment is not to measure light speed, but rather to detect a "difference" between the time of arrival of a signal sent from Earth and recorded by a distant clock and the synchronization time to which the distant clock would be set using Einstein's convention, then the need for a coordinate system is obviated.

 

[Aether]

The point you are missing is that these one way light experiments only measure the one way speed of light IN INERTIAL FRAMES (defined by the first postulate of SR ... not the second one as Aether claims ... and not with what Clj4 is apparrently using as a definition of inertial frames). The experiments cannot say more about the one-way speed of light than this because it is a coordinate system dependent quantity. The experiments agree with SR beautifully, so the one-way speed of light is constant and isotropic IN INERTIAL FRAMES.

Correct, inertial frames are defined by the first postulate of SR and not the second.

 

[Aether]

If the intent of the experiment is not to measure light speed, but rather to detect a "difference" between the time of arrival of a signal sent from Earth and recorded by a distant clock and the synchronization time to which the distant clock would be set using Einstein's convention, then the need for a coordinate system is obviated.

You have a first clock t1 on the Earth, and a second clock t2 on a spacecraft traveling along a hyperbolic escape trajectory. You synchronize these two clocks using Einstein's convention. You "measure" the travel time of a light signal traveling from t1 to t2 which has to be t2-t1=(x2-x1)/c_0 if the clocks are syncrhonized by Einstein's convention. Is there something else to the experiment?

I put "measure" in quotations because this isn't really a true measurement as it is dependent on the coordinate system established by the chosen clock synchronization method.

 

[clj4]

We are not done because you are still not understanding.

Are you defining an inertial frame as a frame in which a freely moving object has a constant velocity (that is, the frame agrees with Newtons First Law)? This is the only way I can see anyone calling the frames of MS theory \"inertial frames\".

First of all, note that is not the relativistic definition of an inertial frame.

But if you wish to use that definition, so be it.
You have admitted that there are coordinate systems in which light speed is not isotropic. Good, it appears we are now in agreement that the speed of light is not a coordinate system independent quantity.

So that answers one of my questions and leaves this one:

-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.


The point you are missing is that these one way light experiments only measure the one way speed of light IN INERTIAL FRAMES (defined by the first postulate of SR ... not the second one as Aether claims ... and not with what Clj4 is apparrently using as a definition of inertial frames). The experiments cannot say more about the one-way speed of light than this because it is a coordinate system dependent quantity. The experiments agree with SR beautifully, so the one-way speed of light is constant and isotropic IN INERTIAL FRAMES.

Looks like you like to beat things to death. I told you already, the whole discussion has always been in the framework of inertial frames.
This is what the 11 papers talk about, this is what the 400+ posts talk about.
You seem to be very hung up on the tensorial formalism of SR/GR. None of the authors of the 11 papers uses this formalism (i.e. what you call "coordinate independent"). This doesn't make the papers any less valid as Aether would like us to believe it.
1.The experimental part is of these 11 papers (and mounting) is valid.

2. The theoretical part (though it does not use the tensor formalism) is valid.

3. Probably if the authors knew about the fixation you have with the tensor formalism they could recast their papers in this notation and get a fresh paper :-) For the time being they appear uniterested in doing so.

4. Therefore all the 11 the papers (and mounting) are valid and yes, "so the one-way speed of light is constant and isotropic IN INERTIAL FRAMES."

 

[Aether]

"so the one-way speed of light is constant and isotropic IN INERTIAL FRAMES."

Correct. What is your definition of an "inertial frame"?

 

[clj4]

Correct. What is your definition of an "inertial frame"?

Read the 11 papers, they'll set you straight.

 

[Aether]

Read the 11 papers, they'll set you straight.

Wrong answer.

Here's some info on inertial frames:
http://plato.stanford.edu/entries/spacetime-iframes/#2

It may seem surprising that, after this insightful analysis of the concept of inertial frame and its role in electrodynamics, Einstein should have turned almost immediately to call that concept into question. But he had a compelling combination of physical and philosophical motives to do so. On the physical side, he realized (along with many others) that special relativity would require some fundamental revision of the Newtonian theory of gravity. On the philosophical side, he became convinced, largely by his reading of Mach (1883), that the central role of inertial frames was an “epistemological defect” that special relativity shared with Newtonian mechanics. (Einstein 1916, pp. 112-113.) Only relative motions are observable, yet both of these theories purport to identify a privileged state of motion and use it to explain observable effects (such as centrifugal forces). Coordinate systems are not observable, yet both of these theories assign a fundamental physical role to certain kinds of coordinate system, namely, the inertial systems. In either theory, inertial coordinates are distinguished from all others, and the laws of physics are said to hold only relative to inertial coordinate systems. In an epistemologically sophisticated theory, both of these problems would be solved at once: the new theory would only refer to what is observable, which is relative motion; it would admit arbitrary coordinate systems, instead of confining itself to a special class of system. Why, after all, should any genuine physical phenomenon depend on the choice of coordinate system?

 

[clj4]

Wrong answer.

Here's some info on inertial frames:
http://plato.stanford.edu/entries/spacetime-iframes/#2

Duh, this is the intro to GR. This is how the tensor formalism gets introduced. Stick to philosophy, Aether, experimental physics is not for you.

 

[yogi]

You have a first clock t1 on the Earth, and a second clock t2 on a spacecraft traveling along a hyperbolic escape trajectory. You synchronize these two clocks using Einstein's convention. You "measure" the travel time of a light signal traveling from t1 to t2 which has to be t2-t1=(x2-x1)/c_0 if the clocks are syncrhonized by Einstein's convention. Is there something else to the experiment?

I put "measure" in quotations because this isn't really a true measurement as it is dependent on the coordinate system established by the chosen clock synchronization method.

What I propose is to start with two widely separated clocks T1 and T2 - both at rest wrt each other, and far removed from the influence of Earth or other masses. We send a signal from T1 at 1pm and it is reflected off a mirror attached to T2 and returns to T1 at 3pm - so by Einstein's convention we now know we should set set T2 to 2pm + augmented by how much time has elapsed on T2 since the signal was reflected by the mirror (In other words we transmit information to T2 after T1 receives the reflected signal at 3pm) We have now synchronized T2. Now at 7 pm as read on T1 and we send a 2nd pulse toward T2. It should arrive at T2 when T2 reads 8 pm. If it does not, we have an indication that something is wrong.

 

[JustinLevy]

Looks like you like to beat things to death. I told you already, the whole discussion has always been in the framework of inertial frames.

No, the discussion has brought up the non-inertial frames described by the fairly general MS transformations many times.

...and yes, \"so the one-way speed of light is constant and isotropic IN INERTIAL FRAMES.\"

Good, you are finally admitting that a qualification is necessary for that statement.

And given that statement, I assume you will now admit this previous statement of yours is incorrect:

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...

The MS transformations are fairly general and can be used as a test theory for experiments to constrain what transformations relate inertial frames. This does not mean all MS transformations yield inertial frames. Also, it does not mean experiment \'disproves\' all the MS transformations that are not lorentz transformations, for experiment cannot disprove a coordinate system (all coordinate systems can be used). It ONLY means that experiment restrict the transformations to be lorentz transformations for INERTIAL FRAMES.

Do you agree with all of this?
If so, we can finally lay this to rest.

 

[JustinLevy]

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.

Now you are making the same errors you complained about Clj4 making.

None of the Mansouri-Sexl transformations parameters are coordinate independent. Therefore experiment cannot constrain them in general. Experiment can only constrain their values for relating INERTIAL FRAMES.

 

[Aether]

Now you are making the same errors you complained about Clj4 making.

None of the Mansouri-Sexl transformations parameters are coordinate independent. Therefore experiment cannot constrain them in general. Experiment can only constrain their values for relating INERTIAL FRAMES.

It is my understanding that the \epsilon parameter selects the coordinate system, and can't be constrained by experiment; but the \alpha, \beta, and \delta parameters are coordinate-system independent parameters that can be constrained by experiment. Do you have a copy of the Mansouri-Sexl papers? I can make them available for download if you don't already have them.

 

[clj4]

The MS transformations are fairly general and can be used as a test theory for experiments to constrain what transformations relate inertial frames.

Correct, no one said anything different

This does not mean all MS transformations yield inertial frames.

No one said this , you seem to be on your way of constructing a strawman.

Also, it does not mean experiment \'disproves\' all the MS transformations that are not lorentz transformations, for experiment cannot disprove a coordinate system (all coordinate systems can be used).

This sentence does not parse.

It ONLY means that experiment restrict the transformations to be lorentz transformations for INERTIAL FRAMES.

Now your strawman is complete. This was the starting point, the middle point and the endpoint of the whole discussion. Have you read any of the 11 papers I listed? This is evident in all of them.

 

[clj4]

Good, you are finally admitting that a qualification is necessary for that statement.

Looks like you keep repeating the same obvious stuff. You keep ignoring the fact that the framework of the discussion has always been the inertial frames of SR. Why do you keep beating the poor strawman? Leave it alone.

And given that statement, I assume you will now admit this previous statement of yours is incorrect:

Originally Posted by clj4
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...

Let me try one more time, in slightly different words : in their papers, in their OWN writing, MS use the premise that light speed is isotropic in ONE ARBITRARY frame (the one that they call "preferential"). In ALL the OTHER frames, light speed is NOT isotropic. This is exactly what you quoted me saying above. Are you quibbling about not adding the qualifier "inertial"? Isn't that obvious enough? If not, then please look up the exact statement in paper I, page 505:

"One easily sees that this modified velocity addition theorem (4.2) does not exclude superlight velocities (duh!) and in fact it does predict unisotropic (sic!) light propagation IN ALL FRAMES EXCEPT \Sigma"

From the Gagnon paper, bottom of page 38:

"...we consider a theory (GGT) which postulates the existence of a preferred or absolute frame of reference in which light propagates isotropically at a fixed speed. IN ALL OTHER reference frames the one way speed of light depends on the state of motion of an observer wrt the preferred reference frame"

I much prefer discussing math and experiments than splitting hairs over philosophy of science. So, if you have anything that can be quantified mathematically, Justin, let's see it. Enough pose and hair splitting.

 

[Aether]

Let me try one more time, in slightly different words : in their papers, in their OWN writing, MS use the premise that light speed is isotropic in ONE ARBITRARY frame (the one that they call "preferential"). In ALL the OTHER frames, light speed is NOT isotropic. This is exactly what you quoted me saying above. Are you quibbling about not adding the qualifier "inertial"? Isn't that obvious enough? If not, then please look up the exact statement in paper I, page 505:

"One easily sees that this modified velocity addition theorem (4.2) does not exclude superlight velocities (duh!) and in fact it does predict unisotropic (sic!) light propagation IN ALL FRAMES EXCEPT \Sigma"

The preferential frame \Sigma is an inertial frame, and all of the others where light speed is anisotropic are not inertial frames. Are you disputing this, or are we just misunderstanding each other in some way?

 

[clj4]

The preferential frame \Sigma is an inertial frame, and all of the others where light speed is anisotropic are not inertial frames.

Can you prove the above statement? With math, not with prose.

 

[clj4]

We are not done because you are still not understanding.

Are you defining an inertial frame as a frame in which a freely moving object has a constant velocity (that is, the frame agrees with Newtons First Law)? This is the only way I can see anyone calling the frames of MS theory \"inertial frames\".

First of all, note that is not the relativistic definition of an inertial frame.

But if you wish to use that definition, so be it.
You have admitted that there are coordinate systems in which light speed is not isotropic. Good, it appears we are now in agreement that the speed of light is not a coordinate system independent quantity.

So that answers one of my questions and leaves this one:

-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.The point you are missing is that these one way light experiments only measure the one way speed of light IN INERTIAL FRAMES (defined by the first postulate of SR ... not the second one as Aether claims ... and not with what Clj4 is apparrently using as a definition of inertial frames). The experiments cannot say more about the one-way speed of light than this because it is a coordinate system dependent quantity. The experiments agree with SR beautifully, so the one-way speed of light is constant and isotropic IN INERTIAL FRAMES.

So the new argument (that you now share with Aether) is that all the other frames in MS are not inertial (i.e. with the exception of the preferred frame).
I will ask you the same I asked Aether: prove it. With math, not with prose. You two guys can work together on this proof.

 

[Aether]

The preferential frame \Sigma is an inertial frame, and all of the others where light speed is anisotropic are not inertial frames.

Can you prove the above statement? With math, not with prose.

See http://www.mathpages.com/home/kmath386/kmath386.htm" reference for the supporting math:

The problem here, as in almost the entire literature on this subject, is the invalid extrapolation from Newton’s first law to all of Newton’s laws...It seems most reasonable to reserve the expression “inertial coordinate system” to those systems of space and time coordinates in terms of which inertia is homogeneous and isotropic, because this is sufficient to unambiguously define a unique reference frame for each state of motion. On this basis, the definition of inertial coordinate systems given in all existing modern textbooks (at least all I have seen) is wrong. (I restrict this to “modern” texts, because clearly Galileo, Newton, and the other 17th century originators of modern physics understood the need for inertial isotropy, but this understanding seems to have been lost in the intervening centuries.

Inertia is not isotropic in a frame where speeds are not isotropic, so if we "reserve the expression “inertial coordinate system” to those systems of space and time coordinates in terms of which inertia is homogeneous and isotropic", then:

The preferential frame \Sigma is an inertial frame, and all of the others where light speed is anisotropic are not inertial frames.

Do you understand and accept the need for inertial isotropy as part of the definition of "inertial frame"?

 

[clj4]

See http://www.mathpages.com/home/kmath386/kmath386.htm" reference for the supporting math:

Inertia is not isotropic in a frame where speeds are not isotropic, so if we "reserve the expression “inertial coordinate system” to those systems of space and time coordinates in terms of which inertia is homogeneous and isotropic", then: Do you understand and accept the need for inertial isotropy as part of the definition of "inertial frame"?

First off, drop the "superior" tone.
Second off, I asked you to do a mathematical proof, what do you know, you come back with quoting a site and some more of your speciality (prose).

OK, so let's look at the website, I know the guy, he's a very respected person in the field,a Cornell professor, so his operational definition of inertial frames is indeed very good. Based on his definition , I will ask you a few things now:

1. In your OWN math, please prove your above assertion, i.e. that all "other" frames in MS are non-inertial

2. In your OWN math, please prove your above assertion, i.e. that all other frames in GGT are non-inertial

3. In your own math, please prove that all the frames employed by SR are inertial (no, it is not obvious, look at his example).

4. What is the relevance of all this new subject that you introduced?
-I.e. how does a more complete operational definition of inertial frames affect the result of the 11 experiments in discussion?
-Does it change the outcome of the 11 experiments?
-Does it invalidate the methodology used by the test theories?
I'll answer this one for you: it doesn't change an iota. It was an interesting detour through terminology and philosophy of science but this is about as far as it goes.

 

[JustinLevy]

In ALL the OTHER frames, light speed is NOT isotropic. This is exactly what you quoted me saying above. Are you quibbling about not adding the qualifier \"inertial\"? Isn\'t that obvious enough?

Apparrently it is not obvious enough, for you clearly are misunderstanding inertial frames. As a reminder, in the quote you state: 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

That quote also directly shows why your complaint here:

This does not mean all MS transformations yield inertial frames.

No one said this , you seem to be on your way of constructing a strawman.

shows the blatant contradiction of your claims. There is no strawman here. You really are claiming that. You really are misunderstanding, and are not seeing the contradictory nature of your statements.


I am glad that you finally admitted that the statement the speed of light is isotropic REQUIRES a qualification to be correct. But you are still misunderstanding this subject.

You keep ignoring the fact that the framework of the discussion has always been the inertial frames of SR. Why do you keep beating the poor strawman? Leave it alone.

It is not a strawman, it is your misunderstanding that is at issue. We finally agree that the statement the speed of light is isotropic REQUIRES the qualification in an inertial frame. But now you seem to not understand the definition of inertial frame used in that statement.

MS transformations DO NOT relate inertial frames (except for when the parameters chosen reduce it to Lorentz transformations). Non-inertial frames have been a part of this discussion the whole time.

4. What is the relevance of all this new subject that you introduced?

It is not a new subject. It has been part of your misunderstanding that we have been trying to correct for some time now. We are making progress, and once you fix this last error, we can be done with this topic and move on.

1. In your OWN math, please prove your above assertion, i.e. that all \"other\" frames in MS are non-inertial

2. In your OWN math, please prove your above assertion, i.e. that all other frames in GGT are non-inertial

3. In your own math, please prove that all the frames employed by SR are inertial (no, it is not obvious, look at his example).

You can use the first or the second postulate of SR to define an inertial frame. Therefore there is no math to show, as #1,#2, and #3 follow directly from definition.

Put another way, if you are claiming GGT or MS frames are inertial frames, you are claiming SR is wrong (since the speed of light is NOT isotropic in these frames). I know perfectly well that you are not claiming SR is wrong, so I hope this will help you realize your errors regarding inertial frames.

 

[JustinLevy]

It is my understanding that the \\epsilon parameter selects the coordinate system, and can\'t be constrained by experiment; but the \\alpha, \\beta, and \\delta parameters are coordinate-system independent parameters that can be constrained by experiment. Do you have a copy of the Mansouri-Sexl papers? I can make them available for download if you don\'t already have them.

Here are the MS transforms http://relativity.livingreviews.org/open?pubNo=lrr-2005-5&page=articlesu9.html
Except for the singular cases (where the transformations yield infinities or are non-invertable), any values of the parameters specify valid coordinate systems.

We can describe the universe with any coordinate system we want, so experiment cannot constrain any of the values in general. Experiments CAN however constrain the parameters in specific/non-general cases such as in inertial frames.

Do you disagree with any of this? and are we now in agreement?

 

[Aether]

Here are the MS transforms http://relativity.livingreviews.org/open?pubNo=lrr-2005-5&page=articlesu9.html
Except for the singular cases (where the transformations yield infinities or are non-invertable), any values of the parameters specify valid coordinate systems.

We can describe the universe with any coordinate system we want, so experiment cannot constrain any of the values in general. Experiments CAN however constrain the parameters in specific/non-general cases such as in inertial frames.

Do you disagree with any of this? and are we now in agreement?

The linked articles says:

The RMS formalism can be made less ambiguous by placing it into a complete dynamical framework, such as the standard model extension of Section 4.1.1. In fact, it was shown in http://relativity.livingreviews.org/open?pubNo=lrr-2005-5&page=articlesu9.html" that the RMS framework can be incorporated into the standard model extension.

I don't necessarily disagree. I haven't studied the standard model extension, so you could be right. How can actual measurements be coordinate-system dependent? That seems to be what you are suggesting.

 

[JustinLevy]

The linked articles says: [-quote removed-]

I don\'t necessarily disagree. I haven\'t studied the standard model extension, so you could be right. How can actual measurements be coordinate-system dependent? That seems to be what you are suggesting.

You asked if I had access to the MS papers, for you felt we were not \"on the same page\" if you will. I linked to that only to show the MS transforms to make sure we were indeed discussing the same transforms. I did not mean to bring that whole page into discussion. So when I asked if you agreed, I merely meant if you agreed with the transformations and my statements.

So I was not talking about the standard model extensions (which is outside the scope of this discussion), but merely what cannnot be said in a coordinate independent manner.

Now, if I understand you correctly, you are asking: how can anything be measured in a coordinate independent manner. Any combination of tensors/vectors that results in a scalar will be a coordinate independent quantity. These invarients are quite important and there has been a strong push by people in the field to focus more on these invarients (the coordinate system independent / \"geometry\" approach which has become the modern view of the theory of relativity) instead of getting lost in the details of coordinate systems.

 

[Aether]

You asked if I had access to the MS papers, for you felt we were not \"on the same page\" if you will. I linked to that only to show the MS transforms to make sure we were indeed discussing the same transforms. I did not mean to bring that whole page into discussion. So when I asked if you agreed, I merely meant if you agreed with the transformations and my statements.

I agree with the transformations. I don't necessarily disagree with your statements; you are raising an issue where I'm not sure of the answer.

So I was not talking about the standard model extensions (which is outside the scope of this discussion), but merely what cannnot be said in a coordinate independent manner.

Ok.

Now, if I understand you correctly, you are asking: how can anything be measured in a coordinate independent manner.

All real measurements are coordinate independent, so what I'm really asking about is the coordinate-independent modeling of physical theories.

Any combination of tensors/vectors that results in a scalar will be a coordinate independent quantity.

And the Mansouri-Sexl parameters \alpha, \beta, and \delta don't fit that description? That is specifically what I'm asking.

These invarients are quite important and there has been a strong push by people in the field to focus more on these invarients (the coordinate system independent / \"geometry\" approach which has become the modern view of the theory of relativity) instead of getting lost in the details of coordinate systems.

Yes, that is what this discussion is really about.

 

[clj4]

Apparrently it is not obvious enough, for you clearly are misunderstanding inertial frames. As a reminder, in the quote you state: 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

That quote also directly shows why your complaint here: shows the blatant contradiction of your claims. There is no strawman here. You really are claiming that. You really are misunderstanding, and are not seeing the contradictory nature of your statements.


I am glad that you finally admitted that the statement the speed of light is isotropic REQUIRES a qualification to be correct. But you are still misunderstanding this subject.


It is not a strawman, it is your misunderstanding that is at issue. We finally agree that the statement the speed of light is isotropic REQUIRES the qualification in an inertial frame. But now you seem to not understand the definition of inertial frame used in that statement.

MS transformations DO NOT relate inertial frames (except for when the parameters chosen reduce it to Lorentz transformations). Non-inertial frames have been a part of this discussion the whole time.


It is not a new subject. It has been part of your misunderstanding that we have been trying to correct for some time now. We are making progress, and once you fix this last error, we can be done with this topic and move on.


You can use the first or the second postulate of SR to define an inertial frame. Therefore there is no math to show, as #1,#2, and #3 follow directly from definition.

Put another way, if you are claiming GGT or MS frames are inertial frames, you are claiming SR is wrong (since the speed of light is NOT isotropic in these frames). I know perfectly well that you are not claiming SR is wrong, so I hope this will help you realize your errors regarding inertial frames.

OK,

Let's see. Since you came on this thread your contributions have been two complaints about formalism:

1. Absence of tensorial formalism in the 11 papers
2. Confusion about the DEFINITION of inertial frames.

So, supposing that the "other" MS frames, per your definition of inertial frames (must comply with POR and must exhibit constant and isotropic speed of light) are now labelled as non-inertial, is there any substantial change?
No , it isn't. The MS formalism still works just the same in terms of separating the "aether" theories from SR and the 11 papers are valid (maybe someone could tell Gagnon that his definition of inertial frames is incorrect, i.e. that assuming light speed anisotropy automatically attracts the "non-inertial" label). This whole thread is about the separability of SR from "aether" theories. I hope we agree on this one, Justin.
What irritated me (not anymore, now that I am writing this) is that you sidetracked the discussion twice:

-when you introduced the subject of the tensor formalism
-when you introduced the subject of defining the inertial frames as above

The first one is trully irrelevant, the second one is interesting in that it sets the terminology on a correct keel.


Yes, Justin, you are right about this one, I claim that SR is correct.

So, now that we get past terminology a few questions:

What is the relevance of the two subjects that you introduced? All you are talking about is the definition of inertial frames. BTW, the Cornell professor has a very good one that introduces an operatorial definition (this is why I asked you and Aether to do a little math, if you apply his definitions you get a very interesting surprise).

-How does a more complete operational definition of inertial frames affect the result of the 11 experiments in discussion?
-Does it change the outcome of the 11 experiments?
-Does it invalidate the methodology used by the test theories?
I'll answer this one for you: it doesn't change an iota. It was an interesting detour through terminology and philosophy of science.

 

[JustinLevy]

Let\'s see. Since you came on this thread your contributions have been two complaints about formalism:

Clj4,
I really am having trouble understanding you. I noticed some questions by rbj and pervect in the thread which I answered. As soon as I corrected you on something, you blew up and started claiming I was disagreeing with all these physicists. I am not. My complaints are with your misunderstanding of the papers. Not the papers themselves.

It appears that once someone corrects you, you instantly become over defensive and will not listen or consider anything people are saying after that. Please try to calm down.

So, to give the benefit of the doubt, I will try one last time. If you really wish to continue this discussion, try asking me some specific pertinent questions, or maybe answer some of my questions to help clarify your position. But if you continue this tactic of trying to claim that everything is a strawman and you never said or meant any of the mistakes we have shown you made, then I must say this nonsense is not worth my time and I am done with this thread.

So let us do a bit of a summary. I believe we agree:
1] SR agrees with experiment
2] we can use any coordinate system we chose to describe the universe
3] the statement light speed is isotropic REQUIRES the qualification in an inertial frame

Number 3 took quite awhile for you to admit, and now you seem to claim that you never denied it. (Even though in post 92 your intial response to my statement on #3 was clearly that you denied it and even claimed There are about 20 physicists that clearly disagree with the \"philosophies\" that you post. They disagree by using math and experiments.) You confuse me in that you eventually did learn your mistake here, but claim there never was a mistake. This tactic has lead to much aggressiveness on your part that is not necessary. I bring this up to help make you aware of it, so that you can hopefully prevent it in the future.


Now, onto the points we still disagree on:
4] What an inertial frame is.

You appear to be using Newtons first law to define inertial frames which is not a sufficient constraint to define an inertial frame.
For example here: post 105
you state: 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.

If you call those inertial frames, you are claiming SR is wrong. Again, I realize you are not making this claim, but you seem to have not yet realized that your statements on inertial frames are contradictory and incorrect.


5] Whether an aether theory can be indistinguishable from SR.

Point #2 above is important in this in that the user Aether seems to be claiming that there is an aether theory that agrees on the physical laws in some preferred frame, and then just uses different coordinate transformations than SR to preserve \"simultaneity\" instead of using inertial frames. (User Aether, of course feel free to correct me if I have misunderstood.)

I complained that this killed the richness of insight that SR gives us. Aether responded in agreement that one may complain along these lines, but his point is merely that such a theory agrees with SR.

In this, he is correct. The modern stance on this is: Aether theories can be indistinguishable from SR. But they provide no new predictive power (in actuality, they give less insight) and are therefore not of theoretical interest.

If you are dismissing me because I am new here, how about arguing with the veteran member JesseM (who is also listed as a Science Advisor on this board) who writes here: His model might be wrong, or it might just be equivalent to relativity but in a less elegant form (like \'aether\' models which make no predictions different than relativity).

Of course modern physics believes SR is correct. But you seem to be twisting this to mean no other theories can match SR\'s predictions ... when it is trivial to construct such a theory (but again, not a useful replacement, I do not want to get the hopes up of any pet theory people out there).

BTW, the Cornell professor has a very good one that introduces an operatorial definition (this is why I asked you and Aether to do a little math, if you apply his definitions you get a very interesting surprise).

This is another tactic that is very annoying. You imply something, but refuse to take a stance and state it (for fear of being shown wrong or something?).

The Cornell professors definition is equivalent to SRs definition (which you should automatically agree with, because I know you are not claiming he is disagreeing with SR). While operationally it is easier to use SRs second postulate to define inertial frames, I actually prefer his definition conceptually.


So if you really wish to continue this discussion,
- please avoid your annoying \'tactics\' that I have pointed out
- please try asking me some specific pertinent questions
- or maybe add new comments on some of my statements to help clarify your position

If you do not wish to do this, I am not interested in continuing this \"discussion\".

 

[JustinLevy]

All real measurements are coordinate independent, so what I\'m really asking about is the coordinate-independent modeling of physical theories. And the Mansouri-Sexl parameters \\alpha, \\beta, and \\delta don\'t fit that description? That is specifically what I\'m asking.

The a,b,d,e parameters (as well as v) are used to specify the coordinate transformations. We can use any coordinate system we chose, so no, we can not measure a,b,d,e (and similarly v) in a coordinate independant manner.

Note that we COULD measure these (except v) for the specific case of inertial frames. There is a slightly less specific case which restricts a,b,d but not e (and of course not v). Reading some earlier posts, I think this may be what is confusing you here. Tell me if this helps.

If we do not restrict our coordinate system to be inertial, but we do require that the time coordinate is the time as measured by a stationary \"standard\" clock, and the spatial coordinates to be that as measured by a stationary \"standard\" ruler, this will restrict a,b,d but not e (or v).

Is that what you were thinking of?


I am still unclear what your ultimate claims are in this thread. If you agree that SR is correct, and you agree that a theory which refers to a perferred frame that can not be experimentally found is making an untestable/unscientific claim, what exactly DO you see in aether theories that attracts you?

 

[Aether]

Point #2 above is important in this in that the user Aether seems to be claiming that there is an aether theory that agrees on the physical laws in some preferred frame, and then just uses different coordinate transformations than SR to preserve \"simultaneity\" instead of using inertial frames. (User Aether, of course feel free to correct me if I have misunderstood.)

This is an explicit claim made by Mansouri-Sexl and others. I believe that it is a correct claim.

The a,b,d,e parameters (as well as v) are used to specify the coordinate transformations. We can use any coordinate system we chose, so no, we can not measure a,b,d,e (and similarly v) in a coordinate independant manner.

Note that we COULD measure these (except v) for the specific case of inertial frames. There is a slightly less specific case which restricts a,b,d but not e (and of course not v). Reading some earlier posts, I think this may be what is confusing you here. Tell me if this helps.

If we do not restrict our coordinate system to be inertial, but we do require that the time coordinate is the time as measured by a stationary \"standard\" clock, and the spatial coordinates to be that as measured by a stationary \"standard\" ruler, this will restrict a,b,d but not e (or v).

Is that what you were thinking of?

I am still learning about these things, and try not to take strong positions here unless there is a specific guiding principle to back it up in Mansouri-Sexl, Zhang, or another credible reference.

I am still unclear what your ultimate claims are in this thread. If you agree that SR is correct, and you agree that a theory which refers to a perferred frame that can not be experimentally found is making an untestable/unscientific claim, what exactly DO you see in aether theories that attracts you?

Most, if not all, experiments to date are consistent with local Lorentz symmetry. I am interested in designing and carrying out future experiments to push the envelope beyond what has already been done in this field. I have a personal theory that predicts a specific and clear violation of local Lorentz symmetry that is beyond the resolution of current technology to detect, but which should be detectable in the not too distant future given the historical trend of increasing precision of detectors. Although I continue to learn interesting details in the course of this discussion, I am personally past the point where the fundamental issue of "Aether theories which are experimentally indistinguishable from SR" is a very interesting subject because there is no question whatsoever that just such an aether theory exists (e.g., GGT and SR represent the same physical theory using different coordinate systems). clj4 is the one who resurrected this thread and keeps it going, not me.