Aether theories which are experimentally indistinguishable from SR.

[CarlB]

Are you assuming the 4th spatial dimension is a compact one? If not, why do we seem to have only 3 degrees of movement? And if so, then is the "preferred reference frame" the same as the one where the diameter is maximized?

Different people treat the proper time dimension differently. I treat it as compact for the reasons you give.

Instead of the diameter of the compact dimension, if I'm going to talk about measurements along the hidden dimension I prefer to measure its circumference. Otherwise you have to define an embedding space or some such. Unfortunately, as with other ether theories, there is no way for us to measure distances in the hidden dimension, so there is no way for us to determine the preferred reference frame (at least with normal matter and light).

What I'm trying to say here is that the death of the preferred reference frame and ether was not from Einstein's showing that it was unneeded. In fact, a preferred reference frame / ether had never been needed in that no one ever had any idea where such a frame existed. They were needed only as a philosophical item in that it could not otherwise be imagined how vibrations could move through a vacuum.

Instead, the death thrust to the preferred reference frame / ether was the requirement that vibrations in it (i.e. light) satisfy the Lorentz transformations for different reference frames. This is a very special symmetry. But if that symmetry arises naturally from a hidden dimension, then the philosophical support for the preference frame / ether returns.

I wrote up a very short and simple 2 page paper on the phase velocity of de Broglie waves and the "proper time geometry", which is what I call Euclidean relativity that may give a better idea of why one naturally thinks of a preferred reference frame when using Euclidean relativity, but does not when using special relativity:
http://brannenworks.com/a_phase.pdf
The paper looks ugly in some versions of acrobat but it prints cleanly. It's not my current thinking on the subject, but it does give a suggestion of how QM and Euclidean relativity interact.

I should note that I wrote the above before I appreciated how many other people were working in the area, so there aren't nearly enough references included. Euclidean relativity is so natural that many authors, myself included, came upon it without knowing that others had already discovered it. The newer (and better) papers deal with general relativity, but my own interest is in elementary particles and fields. So naturally, I came to Euclidean relativity through an exploration of standard model particle symmetries.

Carl

 

[Mortimer]

Mortimer, do you agree that Euclidean special relativity is a type of Lorentz ether theory?

The reason I ask is because it is possible to read a lot of ESR papers without seeing any mention of "ether" or "preferred reference frame", but at least one other person doing work in the field also believes that a preferred reference frame is implied by ESR.
Carl

I guess you're referring to Hans Montanus' AEST (Absolute Euclidean Space Time), which is such a preferred reference frame. In my opinion that is a perfectly valid mathematical framework but I am not in favor of it although I highly appreciate his articles. The point is that there still is no way to determine which frame is the preferred one. Each individual observer's frame still is equally valid as a candidate.

My own opinion on the matter is that there is indeed a preferred frame implied by ESR but it is 5-dimensional, like you said. This means that no single 4-dimensional frame can be preferred. Compare this for instance with a 3-dimensional space holding multiple 2-dimensional planes with different orientations. Each plane is on equal footing with all other planes from the perspective of the 3D space but there is only one 3D space which is the preferred frame.
For a human observer his own 4D space-time in ESR is the equivalent of such a plane, embedded in a 5D space-time that is "fixed" for each human observer. The relative orientation of the 4D environment in the 5D frame is determined by the Lorentz boost, or rotation in SO(4).

Like the 2D plane analogy, this 4D analogy only leads to a preferred frame in 5D if observational skills are limited to 4D (like for us humans). A hypothetical being with 5D observational skills would on its turn treat his 5D space-time as embedded in a 6D frame that would then be the preferred frame, and so on. You could see this as a kind of multi-dimensional fractal.

Rob

 

[CarlB]

It may be of interest that S. W. Hawking's latest paper on black holes uses Euclidean gravitation theory:

"I adopt the Euclidean approach [5], the only sane way to do quantum gravity nonperturbatively."
http://www.arxiv.org/abs/hep-th/0507171

The link is from Peter Woit's "not even wrong" blog:
http://www.math.columbia.edu/~woit/blog/

Carl

 

[clj4]

And if I chase down the reference, will I find what I asked for? Will I find an aether theory that is experimentally indistinguishable from SR?

To everyone:
Come on guys, this is your big chance! Show us that there actually exist aether theories that yield predictions that are as good as those of SR. It shouldn't be too hard, because so many people have told me that such theories exist.

Tom,

Such theories DO NOT exist. This was debated more recently in two-three other threads:

1. The aether theories are not sufficiently developed (they stop at kinematics and lack the electromagnetism)

2. There are experiments (in the electromagnetic space, of course!) that point out the differences between such aether theories and SR. So far I have identified 8 such experiments.

3. As shown by CM Will in a paper dating from 1992, some "aether" theories can be contrived to appear indistinguishable from SR via "adding AD-HOC assumptions that may or may not be true" (cited from the CM Will paper). See also point 6 in Tom Roberts posting:

http://groups.google.com/group/sci.physics.relativity/msg/a6f110865893d962Well, what else is new? We have known all along that the demise of the early aether theories was caused by the requirement of adding an ad-hoc explanation for each new experiment.

So yes, you are right, this is all a smokescreen: there is no "aether" theory that is "experimentally indistinguishable" from SR

 

[clj4]

Tom - here is one citation - don't get the idea I totally endorse everything this guy says - I think he is wrong on his views about Sagnac and GR - but - anyway:
http://redshift.vif.com/JournalFiles/V11NO1PDF/V11N1SEL.pdf.

Yes, this is published in a journal that is well known as a "fringe" (as bordering on crank). Anyways, John Baez and Zhang refer to the Mansori-Sexl theory, published in 3 papers in 1977. This is a serious aether theory that picks up where Robertson (a professor at Caltech) left off.

 

[clj4]

There has got to be an aether theorist willing to fork over the $10,000 or so required to do a tabletop 1-way test. Why hasn't one been done yet? Are they afraid of the answer?

He-he. All the one way light speed experiments (there are 8 papers on them but more are coming) are done by relativists. The results are very clear: no anisotropy.

 

[clj4]

One way velocities are strictly a statement about coordinate systems. Coordinate systems don't have any ultimate physical significance - that's why one-way velocities don't, either.

So basically getting hung up on the issue of one-way velocities is a dead end. It doesn't tell you anything more, or different, about what you can measure. Furhtermore, systems with non-isotropic one-way velocities are more complicated to deal with. As I've remarked in another thread, there can be some justification for changing units or coordinates to make the mathematics and the exposition of a theory simpler. In this case, changing to non-isotropic coordinates makes the math and the exposition of a theory harder, not simpler. So it's pretty much a lose-lose proposition.

Correct. For example: Mansouri and Sexl stopped after the kinematic section. (no dynamic and no electromagnetism). One member of thE Gagnon team, P.Chang went ahead and demonstrated how Maxwell equations transform in the framework of Mansouri-Sexl, a nightmare of ugliness.

 

[rbj]

please forgive my ignorance, but how can an aether theory be compatible with SR (or GR) since movement through the aether at sufficient velocity would result in a measurable difference in the speed of light propagating in different directions? is not the isotropic propagation of light axiomatic to SR?

i s'pose an ad hoc exception to make an aether theory work with the results of the Michaelson-Morley experiment is some theory that the aether travels along with the Earth so the Earth never moves through it at any velocity that would make the M-M experiment come out differently. unless one were to believe that the Earth is at the center of reality to explain why the aether is stuck to it, one would have to contrive a theory that the hypothetical aether sticks locally to massive objects, sort of like the curvature of space-time in GR. then, i guess to disprove that, human beings would have to spend a few zillion dollars sending an M-M apparatus up in the shuttle, as far from Earth as possible and showing that light is just as isotropic there.

to my ignorant mind (i'm just a lowly electrical engineer) aether means non-isotropic radiation of E&M for anyone moving through the aether and, besides never having properties that lend themselves to being measured, this seems totally inconsistent with the wave solution to Maxwell's Eqs. in a vacuum. this is why, i thought, that Einstein believed c to be constant, whether or not he was aware of the M-M experiment in 1905.

 

[JustinLevy]

please forgive my ignorance, but how can an aether theory be compatible with SR (or GR) since movement through the aether at sufficient velocity would result in a measurable difference in the speed of light propagating in different directions?

I have ran into some aetherists that agree with the results of SR, but have some metaphysical belief that there is a one real frame. Basically, they claim that there is one real frame and all calculations must be done in this frame (and the lengths, times, velocities in this frame are the \"real\" quantities, with those being measured in other frames just being \"mathematical conveniences\"). This is just metaphysical, so I see no reason we can\'t dismiss it immediately.

Of course the calculations can be done in any frame, so this will indeed agree with SR. But it is not a valid theory because it adds the metaphysics of claiming only one frame is real, even though we could arbitrarily choose this frame (or equivalently, their theory doesn\'t allow a way to deterime which frame is the real one).

So such a theory will agree with experiment, but is not scientific.

is not the isotropic propagation of light axiomatic to SR?

In inertial frames (frames with the Minkowski metric), yes. But for frames with other metrics, there is no requirement that the speed of light be isotropic (for example in GR). But this does not indicate that GR is an aether theory. In fact, it now allows any coordinate system to be used. The exact opposite of a perferred frame.

i s\'pose an ad hoc exception to make an aether theory work with the results of the Michaelson-Morley experiment is some theory that the aether travels along with the Earth so the Earth never moves through it at any velocity that would make the M-M experiment come out differently. unless one were to believe that the Earth is at the center of reality to explain why the aether is stuck to it, one would have to contrive a theory that the hypothetical aether sticks locally to massive objects, sort of like the curvature of space-time in GR. then, i guess to disprove that, human beings would have to spend a few zillion dollars sending an M-M apparatus up in the shuttle, as far from Earth as possible and showing that light is just as isotropic there.

Aether dragging ideas do not fit with SR (or experimental evidence).

And if you are curious, a M-M apparatus has already been sent up to space. Also, the Gravity Probe B, will be releasing its results soon which tests relativity away from the Earth's surface.

 

[Garth]

And if you are curious, a M-M apparatus has already been sent up to space. Also, the Gravity Probe B, will be releasing its results soon which tests relativity away from the Earth's surface.

See Alternative theories being tested by Gravity probe B.

Garth

 

[clj4]

please forgive my ignorance, but how can an aether theory be compatible with SR (or GR) since movement through the aether at sufficient velocity would result in a measurable difference in the speed of light propagating in different directions? is not the isotropic propagation of light axiomatic to SR?

i s'pose an ad hoc exception to make an aether theory work with the results of the Michaelson-Morley experiment is some theory that the aether travels along with the Earth so the Earth never moves through it at any velocity that would make the M-M experiment come out differently. unless one were to believe that the Earth is at the center of reality to explain why the aether is stuck to it, one would have to contrive a theory that the hypothetical aether sticks locally to massive objects, sort of like the curvature of space-time in GR. then, i guess to disprove that, human beings would have to spend a few zillion dollars sending an M-M apparatus up in the shuttle, as far from Earth as possible and showing that light is just as isotropic there.

to my ignorant mind (i'm just a lowly electrical engineer) aether means non-isotropic radiation of E&M for anyone moving through the aether and, besides never having properties that lend themselves to being measured, this seems totally inconsistent with the wave solution to Maxwell's Eqs. in a vacuum. this is why, i thought, that Einstein believed c to be constant, whether or not he was aware of the M-M experiment in 1905.

rbj

The whole thing started in 1949 when a very respected professor at Caltech (Robertson) produced a kinematic alternative to SR. It was continued in 1977 , by Mansouri and Sexl . They produced a so-called "test theory" of SR. This is also only a kinematic section only (no dynamics and no electromagnetism).
The explanation is long and complicated, the bottom line is that only "aetherists" interpret the test theories of Mansouri and Sexl as "alternatives" to SR. M&S certainly did not view their theory as an alternative to SR. One side effect of the MS theory is that one way light speed is isotropic ONLY in ONE reference frame, in all other reference frames it is anisotropic. We can certainly test this and, by showing this to be false, we can disprove the MS theory. This is very different from the alternatives to GR which are true alternatives.
Again, bottom line is that there is a handful of experiments (8 , so far but more are coming) that put very severe error bars on one way light speed anisotropy. Thus, thru the MS "test theory" we get an even better confirmation of SR's validity.
The MS theory is very clever in that it assumes one way light speed to be anisotropic. The anysotropy is "crafted" in such a way that it cancells out in two-way experiments (such as MMX). This is why one way light speed experiments have become key in refuting the MS theory (In SR, one way light speed is , of course, isotropic).
Hope that this helps.

 

[Aether]

please forgive my ignorance, but how can an aether theory be compatible with SR (or GR) since movement through the aether at sufficient velocity would result in a measurable difference in the speed of light propagating in different directions? is not the isotropic propagation of light axiomatic to SR?

One-way speeds are not measurable in a coordinate-system independent way.

i s'pose an ad hoc exception to make an aether theory work with the results of the Michaelson-Morley experiment is some theory that the aether travels along with the Earth so the Earth never moves through it at any velocity that would make the M-M experiment come out differently. unless one were to believe that the Earth is at the center of reality to explain why the aether is stuck to it, one would have to contrive a theory that the hypothetical aether sticks locally to massive objects, sort of like the curvature of space-time in GR. then, i guess to disprove that, human beings would have to spend a few zillion dollars sending an M-M apparatus up in the shuttle, as far from Earth as possible and showing that light is just as isotropic there.

The Michelson-Morley experiment measures two-way light speed isotropy. This does not distinguish between SR and Lorentz ether theory.

to my ignorant mind (i'm just a lowly electrical engineer) aether means non-isotropic radiation of E&M for anyone moving through the aether and, besides never having properties that lend themselves to being measured, this seems totally inconsistent with the wave solution to Maxwell's Eqs. in a vacuum. this is why, i thought, that Einstein believed c to be constant, whether or not he was aware of the M-M experiment in 1905.

Not at all. See T. Chang, Maxwell's equations in anisotropic space, Physics Letters 70A(1), 1 (1979). See also Eq. (5) of http://imaginary_nematode.home.comcast.net/papers/Gagnon_et_al_1988.pdf" et al. (but ignore the rest of the paper) which is the vacuum wave equation obtained from this formulation of Maxwell's equations.

 

[Aether]

Of course the calculations can be done in any frame, so this will indeed agree with SR...

In inertial frames (frames with the Minkowski metric), yes. But for frames with other metrics, there is no requirement that the speed of light be isotropic (for example in GR). But this does not indicate that GR is an aether theory. In fact, it now allows any coordinate system to be used. The exact opposite of a perferred frame.

All one-way speeds are coordinate-system dependent, but two-way speeds aren't. clj4 disagrees with this.

But it is not a valid theory because it adds the metaphysics of claiming only one frame is real, even though we could arbitrarily choose this frame (or equivalently, their theory doesn\'t allow a way to deterime which frame is the real one).

So such a theory will agree with experiment, but is not scientific.

Claiming "only one frame is real" is not scientific, and neither is claiming that experiments prove that one-way light speed is isotropic. Experiments may one day detect violations of local Lorentz symmetry, and there is no problem with theories that predict such a violation as long as they are consistent with experiments to date.

Aether dragging ideas do not fit with SR (or experimental evidence).

Correct.

 

[clj4]

One-way speeds are not measurable in a coordinate-system independent way.

Repeating false statements does not constitute physics. Nor does it make the respective false statements true.

 

[ZapperZ]

One-way speeds are not measurable in a coordinate-system independent way.

The Michelson-Morley experiment measures two-way light speed isotropy. This does not distinguish between SR and Lorentz ether theory.

Not at all. See T. Chang, Maxwell's equations in anisotropic space, Physics Letters 70A(1), 1 (1979). See also Eq. (5) of http://imaginary_nematode.home.comcast.net/papers/Gagnon_et_al_1988.pdf" et al. (but ignore the rest of the paper) which is the vacuum wave equation obtained from this formulation of Maxwell's equations.

I'm sure this paper has been pointed out, but can you please write a rebuttal to this paper in PRA and submit it to that journal? I looked at the citations to this paper, and there was not even ONE paper disputing either their physics, nor their claim, to being able to determine the one-way speed of light. And this isn't a new paper either!

P. Wolf and G. Petit, PRA v.56, p.4405 (1997).

If you think they have made an erroneous claim, then it is your responsibility to respond to it. Complaining about it on some open forum is not going to cut it.

Zz.

 

[Hans de Vries]

One might hope that this doesn't become another Mansouri-Sexl thread...
Discussing pure SR won't shed any light on this, no matter how much
one extends the dispute.In Quantum Field Theory only Lorentz Invariant wave equations are
allowed. That is, they must physically reproduce effects like Lorentz
contraction and time dilation.

Maxwell’s equations physically reproduce Lorentz contraction, not time-
dilation because it describes massless particles which do not have any
time progression. The wave equations for particles with mass however
do correctly generate time dilation as well.

Note that everything propagates in these theories. Not only the
electromagnetic field but also matter fields propagate via wave-
equations. This is the big difference with the old ether theories.Regards, Hans.

 

[pervect]

I'm sure this paper has been pointed out, but can you please write a rebuttal to this paper in PRA and submit it to that journal? I looked at the citations to this paper, and there was not even ONE paper disputing either their physics, nor their claim, to being able to determine the one-way speed of light. And this isn't a new paper either!

P. Wolf and G. Petit, PRA v.56, p.4405 (1997).

If you think they have made an erroneous claim, then it is your responsibility to respond to it. Complaining about it on some open forum is not going to cut it.

Zz.

A great deal of the argument is over semantics. It may not have made it to PRA, but there has apparently been a lot of argument over these issues in the journals. One such reference was posted earlier in the thread:

http://arxiv.org/abs/gr-qc/0409105

I think this paper makes many good points and a few bad ones (i.e. I dont' necessarily agree with everything in this paper, though I find the abstract itself pretty much on-track).

The axiomatic bases of Special Relativity Theory (SRT) are thoroughly re-examined from an operational point of view, with particular emphasis on the status of Einstein synchronization in the light of the possibility of arbitrary synchronization procedures in inertial reference frames. Once correctly and explicitly phrased, the principles of SRT allow for a wide range of `theories' that differ from the standard SRT only for the difference in the chosen synchronization procedures, but are wholly equivalent to SRT in predicting empirical facts. This results in the introduction, in the full background of SRT, of a suitable synchronization gauge. A complete hierarchy of synchronization gauges is introduced and elucidated, ranging from the useful Selleri synchronization gauge (which should lead, according to Selleri, to a multiplicity of theories alternative to SRT) to the more general Mansouri-Sexl synchronization gauge and, finally, to the even more general Anderson-Vetharaniam-Stedman's synchronization gauge. It is showed that all these gauges do not challenge the SRT, as claimed by Selleri, but simply lead to a number of formalisms which leave the geometrical structure of Minkowski spacetime unchanged. Several aspects of fundamental and applied interest related to the conventional aspect of the synchronization choice are discussed, encompassing the issue of the one-way velocity of light on inertial and rotating reference frames, the GPS's working, and the recasting of Maxwell equations in generic synchronizations. Finally, it is showed how the gauge freedom introduced in SRT can be exploited in order to give a clear explanation of the Sagnac effect for counter-propagating matter beams.

My $.02 on the issue.

Coordinate independent physics is a good thing.

It is difficult to phrase velocity in any other manner than a coordinate-dependent one, however. Measuring any sort of velocity depends, at a minimum, on adopting some standard for "fair" clock synchronization. (To measure a velocity, you need a starting point, a stopping point, a distance measurement between the two points, one clock each at the starting and stopping point, and a way to synchronize the clocks.)

Rapidity does not have this synchronization problem, interestingly enough. (You mark out a course of a known fixed distance first, then measure the time it takes to transverse the distance with a single clock located on the moving vehicle rather than two clocks in the laboratory frame). However, note that you can't measure the rapidity of light in any event - clocks cannot move at 'c'. So it would make no sense to talk about the "rapidity" of light being isotropic, as light does not have a rapidity :-(.

The Einstein clock synchronization is a reasonable and well-accepted approach to making velocity (at a single point in space-time) a coordinate independent quantity. Velocity at distant locations still runs into parallel transport issues in GR, but at least with Einstein clock synchronization, we can define the velocity at a point as a coordinate independent quantity.

Conceptually one could use other sorts of isotropy other than light as the "standard" synchronization method. However, light is IMO clearly experimentally the best method to use. Therfore it is sensible to adopt light synchronization as the experimental standard, IMO.

[add]
For instance, we noted earlier that rapidities don't have the clock synchronziation problem, so we could, conceptually, say that the way we synchronize clocks is so that equal rapidities have equal velocities. Howver, while we COULD do this, it would IMO be a poor idea. For one thing, we are making an assumption - one which is compatible with SR, but might not be compatible with other theories - that it is possible to synchronize clocks in this manner so that the velocity of ALL clocks of a certain rapidity are isotropic.

Probably the only reasonably clean alternative to Einstein clock synchronization is slow clock transport.

If we accept the Einstein clock synchronization method as a standard, then we cannot actually measure the isotropy of the speed of light. We have defined it to be constant. We can, however, measure the isotropy of other things. The issue one might have with the Wolf paper is not the contents of the paper, but rather what they chose as the title of their paper. Hopefully the paper itself makes clear what they actually measured.

 

[ZapperZ]

A great deal of the argument is over semantics. It may not have made it to PRA, but there has apparently been a lot of argument over these issues in the journals. One such reference was posted earlier in the thread:

http://arxiv.org/abs/gr-qc/0409105

I think this paper makes many good points and a few bad ones (i.e. I dont' necessarily agree with everything in this paper, though I find the abstract itself pretty much on-track)

But my point is this. The paper that I cited was published a while back. I went to look at ALL the subsequent papers that cited this paper. Unless I have an outdate citation index (Scitation seems to be quite good), not ONE challenges either its interpretation, or its physics, semantics or not.

I mean, of all the noises generated here, I'm amazed that no one who opposed such a measurement, be it either they don't buy the result, or they think these authors misinterpreted their results, didn't have one single damn thing to officially rebutt this paper.

It takes zero effort to bad-mouth something on here. It takes well-thought out argument and validity of point to rebutt a PRA paper and have it appear in print. So where are they? [I'm waiting for the "conspiracy" theory to rear its ugly head]

.. and I've only singled out ONE such paper in the literature.

Zz.

 

[clj4]

.. and I've only singled out ONE such paper in the literature.

Zz.

...You are very correct. There are at least 10 more, for a grand total of 11 :

1. 3 by Gagnon, Torr, P.Chang etc

http://prola.aps.org/abstract/PRA/v38/i4/p1767_1

2. one by Krisher

http://prola.aps.org/abstract/PRD/v42/i2/p731_1?qid=6c4ab66eee46e0e8&qseq=4&show=30

3. 2 by CM Will

http://prola.aps.org/abstract/PRD/v45/i2/p403_1?qid=630b0f834f891ba4&qseq=20&show=10

4. one by Gianfranco Spavieri

http://prola.aps.org/abstract/PRA/v34/i3/p1708_1

5. 3 new ones by A.Peters. Hermann, etc

http://www.arxiv.org/PS_cache/physics/pdf/0508/0508097.pdf

There may be more, the above were discovered in the protracted arguments with the "neo-aetherist" group of : "Aether", "wisp" and the twin sock puppets "Gregory/NotForYou".

The reference quoted by pervect is very interesting and valuable indeed. Look carefully at point (iv) in section (1.2). It has a very strong message for the deniers of the validity of one-way light speed measurements. It also has a very strong message for the people that maintain that "MS theories are experimentally indistiguishable from SR". Once we read very carefully the reference quoted by pervect, we can return to the 11 papers dealing with the isotropy of light speed and we will notice a common trend: they all make use of rotational frames! Surprise, surprise!

 

[pallidin]

My, what a fantastically interesting topic! Love it!

 

[clj4]

My, what a fantastically interesting topic! Love it!

Yes, it comes on the heels of 400+ posts in another thread ("The consistency(!) of speed of light"). It resulted into a somewhat unique side effect, the step by step "reconstruction" and "repair" of the Gagnon (Phys.Rev. A 1988) paper. Worth reading.

 

[pervect]

The reference quoted by pervect is very interesting and valuable indeed. Look carefully at point (iv) in section (1.2). It has a very strong message for the deniers of the validity of one-way light speed measurements. It also has a very strong message for the people that maintain that "MS theories are experimentally indistiguishable from SR". Once we read very carefully the reference quoted by pervect, we can return to the 11 papers dealing with the isotropy of light speed and we will notice a common trend: they all make use of rotational frames! Surprise, surprise!

So, do we all agree to disagree with Selleri's position on point (iv) in section (1.3), and agree with the paper's synthesis position in section 4?

And to agree with and the operational form of the aximotization of SRT in section 2.3?

(\alpha 1) Kinematical Relativity principle: once Einstein synchronization
has been performed in any IRF, the space-time coordinate transformations
between any two IRF’s have to be symmetric and dependent on
the relative velocity of the two frames alone.

(\beta 1)Ivariancy of the velocity of light: in any IRF, once Einstein
synchronization has been performed, the velocity of light is c along any
path.

And is there also general agreement that axiom (\beta 2) in section 2.3 is equivalent to (\beta 1)?

(\beta 2)Round-trip axiom: The velocity of light is a universal constant c in
any IRF along any closed path.

I suspect lurking disagreements with some posters :-). (For the record, I have to study the last point a bit more myself before totally commiting myself, but I have no objection at all to the proposed axiomatic formulation of SR.)

 

[pervect]

I've been thinking about my concerns a bit, and I guess they go something like this.

As educators and/or popularizers of science, how do we tell students on M,W,F that the speed of light is no longer measured, but is defined to be an exact constant by the NIST

http://physics.nist.gov/cgi-bin/cuu/Value?c

when they read in respectable physics journals (PRLA) on Tue,Thur articles with titles that suggest that the one-way speed of light is currently being measured by experiment?

Is PRLA a good place to bring up this question, really?

 

[clj4]

I've been thinking about my concerns a bit, and I guess they go something like this.

As educators and/or popularizers of science, how do we tell students on M,W,F that the speed of light is no longer measured, but is defined to be an exact constant by the NIST

http://physics.nist.gov/cgi-bin/cuu/Value?c

when they read in respectable physics journals (PRLA) on Tue,Thur articles with titles that suggest that the one-way speed of light is currently being measured by experiment?

Is PRLA a good place to bring up this question, really?

Simple, we tell them the truth : we explain that what is really measured is the degree of anisotropy and that the respective experiments apply very severe error bars on it.

 

[JustinLevy]

Simple, we tell them the truth : we explain that what is really measured is the degree of anisotropy and that the respective experiments apply very severe error bars on it.

That does not answer his question, for if the speed of light is defined as a particular value, the speed of light nor its isotropy can be measured.

As educators and/or popularizers of science, how do we tell students on M,W,F that the speed of light is no longer measured, but is defined to be an exact constant by the NIST
http://physics.nist.gov/cgi-bin/cuu/Value?c

when they read in respectable physics journals (PRLA) on Tue,Thur articles with titles that suggest that the one-way speed of light is currently being measured by experiment?

The short answer: they obviously do not use that definition when trying to measure the speed of light.

The long answer:

First, explain to the students what standards are for. Their purpose is to allow experimenters everywhere to be in as close agreement as possible on what a second, meter, amp, and so on are. Since currently the most precise standards are time intervals, by defining the speed of light to a constant (instead of defining a meter) this allows for better agreement between labs on the units of length and time.

Second, explain to students why such a definition can be used. Special relativity postulates that the laws of physics are the same in all frames with the Minkowski metric (inertial frames), and the speed of light is constant in these frames. Since SR has been well tested and beautifully verified, as long as experiments are analyzed from an inertial frame, this is a perfectly fine means to define our units.

Now returning to your last question:

articles with titles that suggest that the one-way speed of light is currently being measured by experiment?

This requires more discussion that just your question on standards.

Velocities are a coordinate system dependant quantity, so if you read the papers it is necessary for the experiments to describe specifically what they are measuring. These usually fall under two groups:
1) Measuring dependence of the speed of light on the velocity of the source. (experiment shows there is none)
2) Measuring the speed of light in an inertial frame. (experiment shows it is constant)

Number 2 causes some reflection, because an inertial frame is usually defined by the Minkowski metric (using Einsteins second postulate to define an inertial frame). This definition obviously can not be used here, so it is understood that Einsteins first postulate is now used to define an inertial frame (that the laws of physics are the same in all inertial frames). Thus these experiments are a test if electromagnetic oscillations (light) occur in some preferred frame.

Because we are so accustommed to the idea of there not being a preferred frame, sometimes people incorrectly think that the second postulate is a special case of the first postulate. This is not the case. Consider sound propagating in a metal. The physics is the same in all inertial frames, but these oscillations occur in a medium and thus do not look the same in all frames. Similary, if light required a medium, the first postulate could be true with the second being incorrect.

They are two separate postulates. Together they make SR, which agrees wonderfully with experiment.

One-way speeds are not measurable in a coordinate-system independent way.

Repeating false statements does not constitute physics. Nor does it make the respective false statements true.

You two seem to be arguing about two different things.

Aether, do you agree that while velocities can change when transforming to another coordinate system (even between inertial frames), that the speed of light is invarient in inertial frames?

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?

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

 

[Aether]

So, do we all agree to disagree with Selleri's position on point (iv) in section (1.3)

Selleri's point (iv) deals with rotating reference frames, and I have no opinion wrt those at this time.

...and agree with the paper's synthesis position in section 4?

Yes. The paper's synthesis position in section 4 is my position here in a nutshell.

However, we do not agree with the standard approach to the matter of the scientific community, who is used to assuming Einstein’s choice as “the
right one” and Selleri’s choice as “the wrong one”; nor we agree with Selleri’s
opposite approach, which simply overturns this statement. A ”right choice”,
simply, does not exist.

I disagree somewhat with this blanket statement that it is the "standard approach to the matter of the scientific community, who is used to assuming Einstein's choice as the "right one"". Fully informed scientists don't assume this, but within the larger scientific community there are many who have a problem in this regard.

And to agree with and the operational form of the aximotization of SRT in section 2.3?

...And is there also general agreement that axiom (\beta 2) in section 2.3 is equivalent to (\beta 1)?

No objection.

Aether, do you agree that while velocities can change when transforming to another coordinate system (even between inertial frames), that the speed of light is invarient in inertial frames?

Inertial frames are defined by the isotropy of light speed.

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?

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

I am not claiming here that SR is wrong. I am simply pointing out that it is coordinate-system dependent, experimentally indistinguishable from a certain class of aether theories, and that the isotropy of the one-way speed of light is a purely conventional (as opposed to measurable) concept.

 

[ZapperZ]

I am not claiming here that SR is wrong. I am simply pointing out that it is coordinate-system dependent, experimentally indistinguishable from a certain class of aether theories, and that the isotropy of the one-way speed of light is a purely conventional (as opposed to measurable) concept.

Then my point stands even more glaringly by your refusal to address what I have said. Why aren't there any citations or rebuttals to papers such as the one I mentioned contradicting their obvious claim of being able to actually measure the one-way speed of light?

You talk about "fully informed scientists" so freely, so I will ask if you think "fully informed scientists" do their scientific work only in public forums while neglecting pretigious peer-reviewed journals? If they don't, why are you? Where are your papers and rebuttals to these claims?

Zz.

 

[Aether]

One-way speeds are not measurable in a coordinate-system independent way.

I'm sure this paper has been pointed out, but can you please write a rebuttal to this paper in PRA and submit it to that journal? I looked at the citations to this paper, and there was not even ONE paper disputing either their physics, nor their claim, to being able to determine the one-way speed of light. And this isn't a new paper either!

P. Wolf and G. Petit, PRA v.56, p.4405 (1997).

If you think they have made an erroneous claim, then it is your responsibility to respond to it. Complaining about it on some open forum is not going to cut it.

Then my point stands even more glaringly by your refusal to address what I have said. Why aren't there any citations or rebuttals to papers such as the one I mentioned contradicting their obvious claim of being able to actually measure the one-way speed of light?

You talk about "fully informed scientists" so freely, so I will ask if you think "fully informed scientists" do their scientific work only in public forums while neglecting pretigious peer-reviewed journals? If they don't, why are you? Where are your papers and rebuttals to these claims?

Zz.

I said that one-way speeds are not measurable in a coordinate-system independent way. Is there a claim within the paper you cited that clearly contradicts this? The authors claim to have constrained the first-order Mansouri-Sexl parameter \alpha using clocks synchronized by slow clock transport which fixes the coefficient \epsilon (e.g., defines a coordinate system on which the measurements are dependent).

The first-order tests of special relativity discussed in this paper are based on the comparison of clocks syncrhonized with the help of slow clock transport and by means of the Einstein procedure. The coefficient \epsilon in the generalized Lorentz transformation...being fixed by clock transport (I.5.6) the one-way velocity of light is no longer conventional, but a measurable quantity...First-order tests cannot be used to distinguish between special relativity and ether theories, as has sometimes been stated. No such "experimentum crucis" is possible in principle, since the two classes of theories can be transformed into one another by a change of conventions about clock synchronization, as has been shown in I.

 

[ZapperZ]

I said that one-way speeds are not measurable in a coordinate-system independent way. Is there a claim within the paper you cited that clearly contradicts this? The authors claim to have constrained the first-order Mansouri-Sexl parameter \alpha using clocks synchronized by slow clock transport which fixes the coefficient \epsilon.

But herein lies ALL the contradiction of ALL of your (and wisp) posts. One one hand, you keep touting that these things cannot EVER be measured. On the other hand, there are ALL of these claims, ranging from Dayton Miller's paper, etc etc.. that supposedly has SHOWN such variation!

What gives?

And you need to tell wisp to get off piggybacking on top of your posts, because he obviously thinks, based on your posts, that there ARE experimental evidence for such anisotropy.

I was HOPING this is where you would bring me to, because it has puzzled me to NO END that such an issue going on for SUCH a long time on here is going NOWHERE fast. If you TRULY believe that the MS higher order parameter cannot be physically measured (per your quote of the MS paper), and thus ether-no ether cannot be physically verified, what are we wasting all this time here for? Why haven't we gone on to other hobbies such as woodworking?

Have you seen any progress in this after ALL these months and years? How many papers have you published based on all of these discussions that you've had? What tangible worthwhile results do you have to show after all this time? If you were my employee hired to further the cause that you have held, what solid results and proofs that can I show my grant funding source that I've made tangible and worthwhile progress?

Zz.

 

[Aether]

But herein lies ALL the contradiction of ALL of your (and wisp) posts. One one hand, you keep touting that these things cannot EVER be measured. On the other hand, there are ALL of these claims, ranging from Dayton Miller's paper, etc etc.. that supposedly has SHOWN such variation!

What gives?

See https://www.physicsforums.com/showpost.php?p=941509&postcount=206" post.

I do have a personal theory that leads me to examine these false claims of coordinate independent one-way speed measurements, but this isn't a place for personal theories; and even if it was, there is a long incubation period for such a thing.

And you need to tell wisp to get off piggybacking on top of your posts, because he obviously thinks, based on your posts, that there ARE experimental evidence for such anisotropy.

wisp, I encourage you to learn about the mathematics of coordinate-systems from my posts, but nothing that I have said so far can support any claim of experimental evidence for either isotropy or anisotropy of the one-way speed of light which is a mathematical concept that can't ever be measured by an experiment (e.g., in a coordinate-system independent way). The Mansouri-Sexl parameters \alpha, \beta, and \delta parameterize violations of local Lorentz symmetry and these are what is measurable, but not \epsilon.

I was HOPING this is where you would bring me to, because it has puzzled me to NO END that such an issue going on for SUCH a long time on here is going NOWHERE fast. If you TRULY believe that the MS higher order parameter cannot be physically measured (per your quote of the MS paper), and thus ether-no ether cannot be physically verified, what are we wasting all this time here for? Why haven't we gone on to other hobbies such as woodworking?

The \epsilon parameter of Mansouri-Sexl cannot be physically constrained. This means that SR and GGT (aka, Lorentz ether theory, and modified Lorentz ether theory) are the same physical theory in different coordinate systems. Beyond this, different phyiscal theories can predict measurable results.

Have you seen any progress in this after ALL these months and years?

Yes. Some of my initial misconceptions were set straight, some errors in published papers have come to light (e.g., Gagnon et al.), etc..

How many papers have you published based on all of these discussions that you've had?

None so far.

What tangible worthwhile results do you have to show after all this time?

My personal theory is in a tangibly better form for having had these discussions.

If you were my employee hired to further the cause that you have held, what solid results and proofs that can I show my grant funding source that I've made tangible and worthwhile progress?

Solid results and proofs related to my personal theory are proprietary. All that I am currently seeking here is a better understanding of truly mainstream spacetime theories and experiments.

 

[clj4]

Solid results and proofs related to my personal theory are proprietary. All that I am currently seeking here is a better understanding of truly mainstream spacetime theories and experiments.

Don't think so. You are denying the obvious . In the meanwhile, the number of PUBLISHED papers that refute your POV is mounting while you have published absolutely nothing to the contrary.

:

So, do we all agree to disagree with Selleri's position on point (iv) in section (1.3)

Selleri's point (iv) deals with rotating reference frames, and I have no opinion wrt those at this time.

But this is the whole point: all the experiments that DISPROVE the "indistiguishability" of aether theories from SR happen in rotating frames! See here, for a refreshment of your selective memory:http://prola.aps.org/abstract/PRA/v38/i4/p1767_1

http://prola.aps.org/abstract/PRD/v42/i2/p731_1?qid=6c4ab66eee46e0e8&...

http://prola.aps.org/abstract/PRD/v45/i2/p403_1?qid=630b0f834f891ba4&...

http://prola.aps.org/abstract/PRA/v34/i3/p1708_1

http://www.arxiv.org/PS_cache/physics/pdf/0508/0508097.pdf

 

[pervect]

But herein lies ALL the contradiction of ALL of your (and wisp) posts. One one hand, you keep touting that these things cannot EVER be measured. On the other hand, there are ALL of these claims, ranging from Dayton Miller's paper, etc etc.. that supposedly has SHOWN such variation!

What gives?

I don't see any logical contradiction here. Aether is saying these things can't be measured in a coordinate independent way. The papers are indeed saying, "we measured these things", but within the body of the paper is a description of the coordinate system used to measure them.

 

[ZapperZ]

I don't see any logical contradiction here. Aether is saying these things can't be measured in a coordinate independent way. The papers are indeed saying, "we measured these things", but within the body of the paper is a description of the coordinate system used to measure them.

You missed it.

Hand 1 - claims that such a thing can't be measure, so no difference in speed of light in different directions.

Hand 2 - papers that have been cited (especially by wisp) that CLAIM to have observed the differences (I still consider these claims to be highly dubious, especially when they are not reproducible).

Hand 1 contradicts Hand 2.

So the papers on Hand 2 are not the papers that I was citing that claim to have made such one-way measurements but NOT detect any anisotropy.

Are we clear on that now?

Zz.

 

[pervect]

It's quite possible I'm missing something, it's been a long thread.

I think we may have what you call "hand1" being the assumption that Einsteinian clock synchronziation is used. Some such scheme is needed to be able to measure velocities. With this "hand1" assumption, it is not possible to measure any anisotropy in the speed of light. The measurement could be performed, but it is tautological that the answer will be that the speeds are the same, at least as long as there is time-translation symmetry (i.e. the speed of light measured at one time is the same as the speed of light measured at a later time).

"Hand2" may be the assumption that slow clock transport is being used to synchronize clocks. For definitness one might add that the clocks are transported along the same path that the light beam uses to avoid any potential path-dependency issues. Mansouri&Sexyl apparently make the "hand2" assumption, and hence conclude that anisotropy of the velocity of light can be measured. The authors doing the experiments are using RMS's scheme to help interpret their results, so they are implicitly using "hand2" assumptions.

SR itself predicts that experimental results using hand1 synchronization techniques will match those from hand2 . Other theories do not necessarily make this prediction.

"Hand1" and "hand2" are "conventions". Fiddling little conventions, but potentially important. Hence some of the remarks that clock synchronization is "conventional".
Different conventions can be annoying (like -+++ vs +--- signatures for the metric), but cannot always be avoided.

 

[ZapperZ]

It's quite possible I'm missing something, it's been a long thread.

I think we may have what you call "hand1" being the assumption that Einsteinian clock synchronziation is used. Some such scheme is needed to be able to measure velocities. With this "hand1" assumption, it is not possible to measure any anisotropy in the speed of light. The measurement could be performed, but it is tautological that the answer will be that the speeds are the same, at least as long as there is time-translation symmetry (i.e. the speed of light measured at one time is the same as the speed of light measured at a later time).

"Hand2" may be the assumption that slow clock transport is being used to synchronize clocks. For definitness one might add that the clocks are transported along the same path that the light beam uses to avoid any potential path-dependency issues. Mansouri&Sexyl apparently make the "hand2" assumption, and hence conclude that anisotropy of the velocity of light can be measured. The authors doing the experiments are using RMS's scheme to help interpret their results, so they are implicitly using "hand2" assumptions.

SR itself predicts that experimental results using hand1 synchronization techniques will match those from hand2 . Other theories do not necessarily make this prediction.

"Hand1" and "hand2" are "conventions". Fiddling little conventions, but potentially important. Hence some of the remarks that clock synchronization is "conventional".
Different conventions can be annoying (like -+++ vs +--- signatures for the metric), but cannot always be avoided.

But I'm not going by what you wrote, or what I wrote, or what anyone wrote. I am going by what Aether claims. That's why I said there's a contradiction in what he claims - i.e. till his subsequent explanation that he doesn't buy all these papers that claim to detect such anisotropy.

Zz.

 

[Aether]

On the other hand, there are ALL of these claims, ranging from Dayton Miller's paper, etc etc.. that supposedly has SHOWN such variation!

But I'm not going by what you wrote, or what I wrote, or what anyone wrote. I am going by what Aether claims. That's why I said there's a contradiction in what he claims - i.e. till his subsequent explanation that he doesn't buy all these papers that claim to detect such anisotropy.

Dayton Miller's claims are based on a long series of Michelson-Morley (M-M) experiments that measured a non-null (\delta-\beta+1/2) within the Mansouri-Sexl formalism. M-M is a two-way light speed experiment, and the fact that all one-way speeds are coordinate-system dependent is not an issue. What is an issue is that subsequent M-M experiments have measured (\delta-\beta+1/2) to much greater precision than Miller, and they all got essentially null results. Nevertheless, there remains an outstanding issue wrt the interpretation of these results since Miller's interferometer was operated in 'gas mode' and the more recent interferometers were operated in 'vacuum mode'.

There may or may not be similar caveats to the other experiments that you're thinking of but didn't identify specifically.

 

[clj4]

Dayton Miller's claims are based on a long series of Michelson-Morley (M-M) experiments that measured a non-null (\delta-\beta+1/2) within the Mansouri-Sexl formalism. M-M is a two-way light speed experiment, and the fact that all one-way speeds are coordinate-system dependent is not an issue. What is an issue is that subsequent M-M experiments have measured (\delta-\beta+1/2) to much greater precision than Miller, and they all got essentially null results. Nevertheless, there remains an outstanding issue wrt the interpretation of these results since Miller's interferometer was operated in 'gas mode' and the more recent interferometers were operated in 'vacuum mode'.

There may or may not be similar caveats to the other experiments that you're thinking of but didn't identify specifically.

Do you know the expression "non-sequitur"? What does all this nonsense have to do with what we were discussing? Is this just another diversion strategy? (I called you on this tactic several times in the past).
This is a definitely a new one, you are now switching from the one way experiments to the two-way experiments. If you want to discuss this, open a new thread.
Let me make you aware that the U of Berlin people have reenacted the MM, KT, Ives-Stilwell experiments (I am listing all of them just to take away from you the antirelativist arguments all in one swoop) with a very high level of precision. There is no doubt today about the validity of these experiments.
The so-called "non-null results" of the Dayton-Miller experiment have been thoroughly debunked multiple times, please don't bring him into discussion, ok?
To paraphrase you "there remains NO outstanding issue wrt the Miller experiment". Period. Do not bring up gas mode vs vacuum mode, I know where this is leading and it will be cut short very quickly.

 

[yogi]

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. The many thousands of articles dealing with light isotrophy, time dilation and space contraction can usually be traced to dissatisfaction with the explanations of the results (or the lack of a physical explanation). Maybe Aether's ideas are shear folly, but at this point he is in good company - near the end of his life Einstein confessed that he believed not a single one of his theories would survive the test of time.

 

[ZapperZ]

There is room for alternative spacetime formalisms w/i the totality of experimental results -

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.

If you continue with this line of irrational claims, I have no choice but to conclude that your are selling quackeries and will be forced to deal with it per our Guidelines.

Zz.

 

[clj4]

That does not answer his question, for if the speed of light is defined as a particular value, the speed of light nor its isotropy can be measured.

You are mixing two things:

1. One way light speed cannot indeed be measured but two way can (and has been)
2. Light speed is ISOTROPIC. One way light speed isotropy HAS BEEN successfully confirmed.
There are about 11 papers , published in Phys. Rev that say that..

 

[JustinLevy]

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?

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.)

 

[clj4]

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 .

 

[yogi]

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.

 

[JustinLevy]

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.

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).

 

[ZapperZ]

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?

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.

 

[Aether]

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?

 

[clj4]

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.

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?

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.

 

[clj4]

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.

 

[yogi]

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.

 

[Paulanddiw]

I'm curious. Do you have a link, or something, about M-M apparatus in space?

Thanks