Of course the paper isn't ``silenced''-anyone can read it. It's just that the claims about the relation between the Sagnac effect and special relativity that are claimed it makes are wrong, that's all. The paper doesn't make any claim about ``demolishing'' special relativity. That many people seem to think it does, doesn't mean it does.

It's nothing new that a rotating frame isn't an inertial frame and that, in a non-inertial frame, relative velocity depends on the path.

So, instead of writing nonsense, it would be better to actually read about the Sagnac effect, e.g. Article The Sagnac effect in general relativity

sorry but the experiment was modified for a constant linear speed thus an inertial frame of reference as also the title "elegantly" implies ... in a uniformly moving fiber.

Ευχαριστώ Εμμανουήλ, δεν το γνώριζα. Θα το λάβω υπόψη μου στην έρευνα που κάνω.

Να 'σαι καλά Γιώργο. Ευχαριστώ.

The notion of SR that c-v = c+v is false.

Light speed can not be absolute.

Unless, this paper is properly post-peer reviewed and disproved, it stands as it is, thus humbly demolishing SR. It is since 2003 now without any review as far as I know. There is no reason for me to doubt the validity of their measurements unless a review paper proofs otherwise.

Since my immediate discipline is not in physics I don't really care to be blamed as an heretic of SR.

Emmannouil

by the same tong: WOULD THE GRAVITATIONAL WAVES GW BE THE ETHER?

See the video -- https://www.youtube.com/watch?v=L7XqMuIPtrM&feature=youtu.be -.  - on the gravitational waves...

*** It seems to me the "mysterious Ether' would be the gravitational waves GW...The Michelson and Morley Interferometer designed in 1907 to detect the ETHER and, FAILED, have the experimental setup similar to that shown in the video above...

The mentioned interferometer gave the Nobel prize to Michelson Morley Experiment to detect the existence of ether, but it has failed... Thanks

SEE (2016): https://www.researchgate.net/post/Do_you_agree_See_Gravitational_waves-GW-https_lnkdin_eBbhD8S_It_seems-to_me-the_mysterious_Ether_would_be_the_gravitational_waves

Dear Emmanouil,

You are an heretic and not good believer to the 'prophet' of our modern Physics, 111+2 years now.

I'll suggest to the Highest Council for Orthodox Physics to be punished characteristically in order other Physicists not to feel even a temptation to oppose the Orthodox view...

:)

(I am joking)

Seriously now:

• nobody cares if an experiment disproves relativity theories, they are made for believers: a believer will never oppose his 'guru'
• a set of definitions that measure what they expect to measure will never be abandoned by scientific community
• ask CERN to accelerate a non charged particle: I have done it several years from now, nobody answered. they continue their ridiculous circle experiments with charged only particles
• the generalization of the 'first belief' is much worse: see recent LIGO adventures and you don't need more search

Only a massive mockery will lead to something, after many - many years...

Dear Professor Demetris Crristopoulos,

Thank you for sharing your opinion in this thread here.

Kind Regards,

Emmannouil Markoulakis

TEI of Crete

What's interesting is how many people, that haven't studied physics in general or learned special and general relativity in particular, nevertheless feel that they can say anything on those particular subjects and actually try to. There's no point to it. Why should anyone, that isn't a physicist, hold strong-and meaningless-opinions about them, instead of studying them? It's meaningless to have an opinion about a technical subject. Either one knows it or one doesn't.

...just saying you don't know the answer to my question?

I invited the authors of the paper here in this thread

Let us first look at Newtonian physics.

There we have a relativity principle: the one that says that uniform motion is unobservable and that transformations between inertial reference frames are Galilean.

Clearly, Newtonian physics holds for accelerated systems as well as for inertial ones. To describe an arbitrary system, however, I must *describe it* from an inertial viewpoint, or else introduce unpleasant ``pseudo-forces''

Now relativity: it is similar, except for the fact that now the transformations between inertial frames are Lorentz, and mix up space and time. Also, they maintain the speed of light constant.

Again relativity holds for accelerated systems: the highest accelerations reached on Earth, in particle accelerators, are perfectly well described by relativity. On the other hand, whenever we describe a system in SRT, we should describe it using coordinates that are inertial, unless we are willing to deal with the SRT equivalent of pseudo-forces.

So it is good discipline to describe everything in SRT from an inertial frame. What makes the Sagnac effect apparently complicated, are the repeated attempts to treat it in the corotating frame. In the rest frame of the disk, it is quite simple.

On the other hand, if your system is rotating uniformly, or rotating in the more complex geometries proposed by the paper, there is no reason to suppose your system will behave as the corresponding system at rest: there simply is no equivalence between an inertial and a non-inertial system.

Note that, in spite of the authors' using the expression ``uniform motion'' the fiber's motion is by no means uniform: there is at any time always one stretch of optical fiber going at speed v and another at speed -v.

Further, we may see that throughout the paper, the authors rely on the usual theory of the Sagnac effect, and nowhere do they argue for a violation of SRT.

A footnote concerning the paper: it was published in Physica A, a very highly respected journal, and a later follow-up appeared in Physical Review Letters in 2004: you do no get more ``mainstream'' than that, and being published in PRL is a quite high level of exposure indeed. It was cited 18 times, which certainly shows people are not unaware of the result. The paper has thus in no way been ``hidden''.

qoete:

" Further, we may see that throughout the paper, the authors rely on the usual theory of the Sagnac effect, and nowhere do they argue for a violation of SRT. "

That's because there are not stupid and want to make it to the publication!!...maybe I'm the stupid here for bringing this matter...nevertheless c-v = c+v sounds uniformly stupid as well...

quote:

" A footnote concerning the paper: it was published in Physica A, a very highly respected journal, and a later follow-up appeared in Physical Review Letters in 2004: you do no get more ``mainstream'' than that, and being published in PRL is a quite high level of exposure indeed. "

18! citations since 2004 for a PRL publication... what an amazing achievement indeed!!...

The fundamental postulate of Special Relativity is that light propagates in empty space always with a definite velocity c relative to an inertial reference system.

It is very unfortunate that in his famous 1905 paper Einstein neglected to include the crucial proviso that I’ve emphasized here by bold italic. That oversight was rectified later.

The rotation of the apparatus employed in the Sagnac experiment means, of course, that the measured comparison of light speeds for the two counter-rotating beams are measurements relative to a reference system co-moving with emitter and receiver, which obviously not "inertial". The result needs to be interpreted by referring the situation to an inertial reference system (which, of course, does not rotate with the apparatus). A simple calculation shows that, relative to an inertial system, the two beams travel different distances at the same speed c. Why this is so can be understood intuitively by means of a simple diagram illustrating schematically what is happening from the viewpoint of the inertial system: https://www.flickr.com/photos/ericlord/40960333652/in/dateposted/

There is no big mystery here. Special Relativity is under no threat from the Sagnac phenomenon!

@ Eric Lord

qoete:

" ...different distances at the same speed c " .

Never heard about this explanation for the Sagnac effect?!!

Can you please Sir, provide us with a reference paper supporting this amazing claim?

https://www.youtube.com/watch?v=Gsat054VEp4&index=2&list=PLntckZdDvmyW97XeYk3VWFsj7oXRRuFFg

Emmanouil: ''18! citations since 2004 for a PRL publication... what an amazing achievement indeed!!...''

Not so bad, the average PRL paper has 8.4. The point is that there can be no talk of a silenced paper.

As to the explanation given by Eric Lord, it is the simplest possible: the light beam goes around the disk, say, in the same direction as the disk. After having made a full turn in the inertial system, the beam finds he needs to go a bit further to get to the original point on the disk, whereas the beam that is going the other way meets the original point earlier.

If you use these same arguments to analyse the cases mentioned in the article, you will get complete agreement.

The initial section of Malykin may give you the basic idea. The trouble is, much work on Sagnac uses propagation in media, where technical issues arise. However, you should really not need a reference for that: this is a high school computation, all you need to do is to check that your final result coincides with the literature.

Dear Emmanouil ~

F. Leyvraz already answered the question you asked me.

A simple analogy: two racing cars start at the same position at the same time on a circular track. They go at the same speed but in opposite directions. Obviously, if the position of the finishing line is moved clockwise during the race, it’s unfair to the driver who goes clockwise. He has further to go! It’s that simple. (-;

Dear Emmanouil,

I'm not a relativist at all!!

This is Physics and not even complicated!!

The Sagnac effect does not disconfirm at all Special Relativity (unfortunately).

It is simply a confirmation of the constancy of the speed of light in a closed loop (two way).

It is all based on the anticipation and retardation of light in reaching a moving point.

A moving emitter in circular motion shoots in both directions:

a) on one hand the emittier follows one light beam,

b) on the other hand the emittor goes against the other beam.

If the emitter was still, the beams would take the same time T to reach it from opposite directions, depending on the length of the track H and the speed of light c . T=H/c.

IN this case it takes a bit more time for the beam which the emitter was chasing T'=T+T*v/c and a bit less time for the beam heading against T''=T -T*v/c

these discrepancies are the reason of the fringe shifts at the interferometer.

If no interference patterns between the light beams were not found, the light should not have ahd a finite speed, since an infinite speed would be required to reach from both direction at the same time hence T=0.

IN this case SR would be in trouble since it is based on the (constancy and) finiteness of the speed of light as being c. So basically the Sagnac effect supports SR .

Emmanouil ≪... what an amazing achievement≫ ≪... this amazing claim?≫

No need to be amazed so easily :-)

If you read the first Einstein paper on relativity, you will see him starting out with essentially the same argument as Eric. Described from the platform, a light pulse fired from the middle of a moving train will have to travel a longer distance in the forward direction than backwards, before hitting the end walls of the carriage. Hence the approaching speeds are found to be respectively c-v and c+v, with c the speed of light. So why don't people in the train carriage detect this difference? Because of a relativistic symmetry in the wave equation for light (and, on closer look, the dynamics of everything else in the carriage). Einstein made that symmetry explicit by introducing a natural way to synchronise clocks in the carriage.

So, the essence of the Sagnac problem is: Why couldn't the same thing be done if the train was moving in a circular tunnel of very-very long circumference? In fact, it could be done locally in the carriage, because the local relativistic symmetry is still there (neglecting corrections due to the tiny bending of the tunnel, necessary to make it circular). Moreover, the same synchronisation can be performed within and between each carriage of the train, and between one train and the next in front of it, making the local relativistic symmetry explicit at each step.

So, what makes the difference between trains on a straight and circular lines? It is topology. One can synchronise clocks on train 1 with train 2 (moving at the same speed), 2 with 3, ..., 314159264 with 314159265. However, right in front of train 314159265 runs train 1, which has already synchronised its clocks. And, alas, it turns out that the clocks on train 314159265 is not synchronised with train 1. Ultimately for the reason given by Eric, that light traveling in the direction with the trains have to travel a longer distance to reach back to the same train, than the light travelling in the opposite direction. In an absolute sense.

The circle topology breaks global relativistic symmetry. But this will not be noticed by people in a single wagon performing local experiments of finite duration. If our spatially flat universe has global periodic symmetry (like a 3-torus) we may be people in such a wagon.

@Professor Kåre Olaussen ,

Interesting analysis ans perspective of SR. Thank you.

However this analysis holds only when a single particle quanta or photon of light is considered and not light as a continuous wave.

I am sure Einstein was thinking on the latter.

Dear Stefano Quattrini ,

I don't think that you gave a correct description of the original circular motion Sagnac clasical experiment or you are wrongly informed about it.

Notice that the Clasical Sagnac experiment does not produce different travel distances as claimed by others in this thread. The light splitter remember was also moving therefore travel distances are the same for both light beams. Therefore Sagnac succeeded in proving what Michelson-Morley failed to do, that, speed of light was controlled by aether medium therefore demolishing SRT.

Most of the explanations given here are wrong and the only excuse really is that circular motion of Sagnac apparatus was not an inertial frame of reference. But now this 2003 paper is applying the Sagnac experiment for an inertial frame of reference and proves that the speed of light is relative to the source or target linear constant speed!, So there are no excuses really left apart of disputing the validity of the 2003 modified Sagnac experiment for an inertial frame of reference.

Here in this video tutorial is the correct animated simulation of the original Sagnac experiment and what the historic implications were:

https://www.youtube.com/watch?v=BcDLCWvMiP8&feature=youtu.be

Kind Regards,

Emmanouil Markoulakis

''Clasical Sagnac experiment does not produce different travel distances as claimed by others in this thread.''

The arguments presented by everybody in no way depend on the emitter being, or not, in motion. Surely the distance between the point of departure and the point of arrival in the comoving frame is the same for both beams, but in the inertial frame it is not.

But now this 2003 paper is applying the Sagnac experiment for an inertial frame of reference

Quite mistaken: the paper uses, for example, a geometry in which the fiber goes round 1 circle, then in a straight line, then round another circle and then back to th e initial circle along another line.

Clearly the two lines move at equal speeds, but different velocities. Each straight line can be put in an inertial system, but you can never put the entire system in one inertial reference frame, because various velocities (various directions) always coexist.

What the paper insinuates is, that it has shown that straight line motion ``contributes'' to the Sagnac phase. The problem with this is that, as beautifully explained by Kåre, the Sagnac effect is global, and thus cannot be attributed to one part or another of the trajectory.

As an analogy: if you travel round the world from east to west, you lose a day: Throughout your trip you will, overall, see one less sunset than all those who stayed at home. This would also happen, of course, if the earth were a rotating cylinder having two straight line segments. Does it make sense to say that any particular part of Earth is ``responsible'' for you losing the day? What the authors attempt to do is roughly along those lines, but they do not follow the argument to any clear conclusion.

The experiment is certainly nice and well done, and as such surely deserved the publication it got, in what is arguably the most prestigious physics-only journal. But the authors' other claims are not well argued for, and would be incorrect if the authors had made them.

Emmanouil ≪However this analysis holds only when a single particle quanta or photon of light is considered and not light as a continuous wave. I am sure Einstein was thinking on the latter.≫

In the article Einstein refers to communication by light signals, which must be limited in space in time. What Einstein was thinking, without writing it down, nobody can be sure about. It is anyway of no relevance, except for the history of science, as are also his writings. It is the ideas, as developed further, that are of importance.

Emmanouil ≪The light splitter remember was also moving therefore travel distances are the same for both light beams.≫

Isn't it precisely because the light splitter is moving that one path is longer than the other? Isn't that exactly what Eric's figure show you?

So now you are telling me that light is subject of the Coriolis effect?...

So why then a rotating Earth is considered as a inertial frame of reference and Sagnac rotating table is not?

Emmanouil ≪So now you are telling me that light is subject of the Coriolis effect?...≫

Huhh? How on earth did you arrive at this conclusion?? I don't believe I have ever mentioned the Coriolis effect explicitly (nor implicitly) in this thread. In fact, in the post with my long explanation I took care to dismiss all such kinds of effects as been negligible/neglected. Because they are irrelevant to the main issue.

Emmanouil ≪So why then a rotating Earth is considered as a inertial frame of reference and Sagnac rotating table is not?≫

That was the main issue of my long explanation. For local experiments on the surface of Earth, local relativistic symmetry is applicable (with corrections of no relevance to the main issue). If one tries to make a global experiment, there is again a topological obstruction. It is not possible to make a global Einstein synchronisation of clocks around (say) the equator. For observers stationary on the rotating surface, after a full round the last clock is out of sync with the first by some 200+ microseconds. This is an effect which must be (and is) accounted for in global navigation systems like the GPS or GLONASS. For Sagnac rotating table experiments, this global topological effect is in fact the main property to be exploited.

So, in both systems global relativistic symmetry is not predicted/expected to be valid. In both systems local relativistic symmetry can, under certain conditions, be expected to be valid. I.e., with negligible corrections; it depends on the size of the experiment, and other physical parameters. The speed of electromagnetic waves in the earth atmosphere is not always c (or even close to c); it depends on the wave frequencies.

Emmanouil: on the subject of Earth: you may be asking: why does the Sagnac effect not need to be taken into account when looking at experiments such as Michelson-Morley? The point is that, in Michelson-Morley, there are no counterpropagating beams. The two beams in MM follow different trajectories, whereas in Sagnac they follow the same trajectories in opposite directions.

The Earth's rotation has, of course, been detected by Sagnac interferometry, both in GPS experiments and in experiments in which a ring interferometer is kept at rest in an earthbound laboratory. The Sagnac effect due to the Earth's rotation is then readily measurable.

Emmanouile - here is what Michelson wanted to measure : how much longer light takes at its constant speed c (a la Maxwell) to move from point A to B due to the distance getting longer due to the motion of earth . A 90 degree turn of the attached is equivalent to a perpendicular arm .

Dear Dr. Hanna Edwards,

I know exactly what MM superior motive was in conducting their experiment. However, no one here is really wiling to let go of an dead man's misconception 100 years old which is really slowing down mankind evolution.

And PS.: Thank you so much for sharing this // Our experiment is important because it shows that the time-difference effect also occurs for uniform motion. //

Because it is a fact that when i walk away from a signal the signal takes longer to reach me . When i walk towards it - it takes shorter to reach me . And the source is irrelevant after the signal is emitted , so i can attach it to myself with a stick . So this has been done .

Which means that myself and a source having zero relative motion (as we can perform this on the north pole !) the signal takes longer when moving in my direction than the source direction .

quote:

" The Earth's rotation has, of course, been detected by Sagnac interferometry, both in GPS experiments and in experiments in which a ring interferometer is kept at rest in an earthbound laboratory. The Sagnac effect due to the Earth's rotation is then readily measurable. "

...of course...and for the record here, can you show me the results of this Sagnac ring laser interferometer experiment measuring the Earth's rotation? I'm interested.

Article The Sagnac effect and its interpretation by Paul Langevin

quote:

" Isn't it precisely because the light splitter is moving that one path is longer than the other? Isn't that exactly what Eric's figure show you? "

You are telling me now that the light gets "pushed over" in one direction by the splitter surface?!! :)

I am impressed how you people get the impression that light is independent when at a constant velocity inertial frame of reference but can bullied if in an rotational accelerating frame of reference!!...

There is no point convincing any one here since your minds are set.

And you didn't convince me at the slightest either.

So let us agree that we disagree and shake hands and depart.

Emmanouil - i know that "you" know . I was "trying" to present an argument at the strength of proof . But you are right - arguing with certain personalities is pointless - and the reason why i do this - is working stuff out for myself - collecting and perfecting .

Dear Emmanouil,

Emmanouil Markoulakis

Special Relativity remains valid even without the second postulate of the invariance of light speed. In fact, Lorentz transformations of the first postulate can be derived with no need of the second postulate .

The behavior of light is not the pillar on which special relativity stands.

It seems that your question was born dead.

Issam - please tell us the pillar on which special relativity stands if it is not the equivalence of inertial reference frames ?

Issam,

"Lorentz transformations of the first postulate can be derived with no need of the second postulate . "

as usual you come out with some blunder!!!

"The behavior of light is not the pillar on which special relativity stands. "

try to make it anysotropic and see if SR still stands.

@ Issam Mohanna ,

You are dead wrong.

Without the second postulate there is no Einstein SR just Galileo relativistic theory.

@ Stefano Quattrini ,

I am not talking about the laser ring interferometer but the classical original Sagnac experiment.

About anisotropic speed of light: if you use a non-conventional synchronisation, which leads to light being propagated at different speeds in different directions, then indeed the formulae for calculating the times and positions of events will differ, just as, say, the formula for the distance between two points in the plane is different if the points are described in Cartesian or polar coordinates.

But, apart from the differences in the formulae, once you ask whether there are observable differences, it turns out there are none. Tangherlini, in particular, has provided such an equivalent reformulation fo STR, in which the one-way speeds of light may be different. It is all very much more complicated the the Lorentz transform, but it is quite consistent.

If light propagated with different speeds in different directions, in an objective sense, this would have shown up in atomic physics. Since this has not been detected, the possible variation of the speed of light with direction has been constrained to 1 part in 10**28..

An accurate measurement of the “one way speed“ of anything between A and B depends on the synchronization of the clocks at A and B. That’s not SRT its just common sense.

In SRT the parameter t of an inertial frame is defined so that light speed relative to that frame will be c. That’s what the “Einstein synchronization method” of 1905 was all about − its purpose was to demonstrate that the parameter t "makes sense".

The “GPS synchronization method” is equivalent to synchronizing all the clocks on a circle of latitude with the t of the Earth Centred Inertial (ECI) frame. That’s not the time parameter for a (local) inertial frame fixed to the Earth’s surface. Hence the “anomalous” Earth-bound experimental result “(c + v) eastward, (c − v) westward”. From the point of view of SRT and the ECI reference frame light speed is c, eastward and westward, but the distances travelled eastward and westward are not the same.

I’ve already attempted to explain these simple facts in other RG discussions. I discovered that those who want to insist that "SRT is wrong" won’t even try to think about it!

Hanna Edwards

You wrote," please tell us the pillar on which special relativity stands if it is not the equivalence of inertial reference frames ?"

The equivalence of inertial reference frames is not of the second postulate but instead of the first postulate , which is a principle of relativity yielding two group representations: Galilean and Lorentzian, where each is of n-types of frame-of-reference transformations independently of the second postulate of the invariance of light speed, where n is a non-zero natural number, and up to you to choose.

It is a tiny example lesson how mathematics can teach physics especially in relativity and particle physics.

Enjoy watching the attached, delicate, and very short YouTube video by Mathematical Physicist Peter Woit at Columbia University ,explaining the relation between Group Theory and Laws of nature.

https://youtu.be/c9tNoH6RB-k

Everything really you want to know about the Sagnac vs SRT clash!

http://www.conspiracyoflight.com/SagnacRel/TheSagnacEffect.pdf

@Eric Lord

quote:

" Dear Emmanouil ~

F. Leyvraz already answered the question you asked me.

A simple analogy: two racing cars start at the same position at the same time on a circular track. They go at the same speed but in opposite directions. Obviously, if the position of the finishing line is moved clockwise during the race, it’s unfair to the driver who goes clockwise. He has further to go! It’s that simple. (-;"

No, paths are exactly same distance.

Erik ≪I’ve already attempted to explain these simple facts in other RG discussions. I discovered that those who want to insist that "SRT is wrong" won’t even try to think about it!≫

In the end people are free to live with their misconceptions; in most cases that is harmless. Sometimes their objections can even inspire one to think through some issues in more detail .

Actually, serious searches for Lorentz Invariance Violation have been a major field in fundamental physics this century; it is certainly not a topic that "mainstream physics" try to silence. There exists a yearly updated source about such searches, maintained by Kostelecky and Russel, https://arxiv.org/pdf/0801.0287.pdf. It was last updated this january.

The basic idea, as I understand it, is to assume that the maximum velocity (speed of "light") can be different in different sectors of the Standard Model of Particle Physics, and to parametrise such violations (taking into account apparent violations that can be removed by coordinate transformations). Hence, a thinkable violation in some area which is difficult to measure directly, must also show up in many other types of experiments. This makes it possible to test violations by use of atomic physics (where very high accuracy can be obtained) and particle accelerators (where particles move very close to the speed of light, in the frame of the accelerator).

The one part in 1028 maximum variation in the speed of light, that I mentioned above, can be found in this article: https://arxiv.org/pdf/1610.08188.pdf, later published in PRL. I think the result is to be interpreted with respect to a time synchronisation where the maximum speed of electrons and nuclei is isotropic.

A single Sagnac experiment does not test Lorentz Invariance Violations. But the fact that it works in exactly the same way as the earth rotates and moves around the Sun does provide some support for the relativity principle, since the (approximately) inertial frame of the experiment is constantly changing relative to any possible absolute frame.

reference: http://www.conspiracyoflight.com/SagnacRel/TheSagnacEffect.pdf

quote taken from above reference by Doug Marett :

...It is often argued that the predictions of Special and General Relativity have been continuously verified and that therefore the theory is unquestionable. However, other theories, such as Lorentz ether theories modified to take into account gravitational effects, can also make similar claims.

There are in fact multiple mathematical routes by which a correct prediction can be arrived at, but these theories may imply very different interpretations of what our physical reality is. And this is at the heart of what is wrong with the theory of relativity – it may make successful predictions based on math, but implies a nature of time and space which are not only inconsistent with logic and reason, but are even contradictory. Our interpretation is that these problems arise because of the switch from the absolute time / variable speed of light of Lorentz (1904) [13] to relative time / absolute speed of light of Einstein (1905) – two stances which are only slightly different mathematically. In Lorentz’s favour, the Sagnac effect demonstrates that depending on the placement of the observer, it is possible to see this variable speed of light and to confound apparent time dilation.

Our analysis of Einstein’s light clock has shown that it will always count in error if the speed of light is not C in the moving frame. And further, our thought experiment with sidereal clocks has shown that the entire premise that time dilation corresponds to a change in “real” time is highly questionable.

So when countered with the argument that General Relativity can explain the Sagnac effect, we might ask, why bother? If time dilation is an illusion, then the entire 4D time-space continuum of Einstein should be considered, to use his own word for the aether, “superfluous.”[7] "

Dear Thierry ~

Me: "In SRT the parameter t of an inertial frame is defined so that light speed relative to that frame will be c."

Thierry: “The question is if this definition holds. It will probably be self-consistent inside SRT, but is it Nature-consistent?”

Yes, it is! Electromagnetism is a predominant component of Nature. All its known properties are encapsulated in Maxwell’s equations which contain the independent variable t, which denotes time, and a fundamental constant c identified as the speed of propagation of electromagnetic waves. If Galileo’s “Principle” (which essentially means that all inertial reference frames are equivalent for the expression of physical laws) is accepted, then SRT is the inevitable conclusion.

(Sorry, I can’t comment on your final paragraph because I can’t understand it. How can a velocity be measured at “one place and time”??)

Dear Emmanouil ~

Einstein’s relativity and Lorentz’s aether theory are experimentally indistinguishable. It is therefore expedient for physicists to choose to work with the theory that is conceptually simpler. Recall that Lorentz’s motivation for constructing his theory was to show how “speeds relative to the aether” could be undetectable, and thereby to “explain” the Michelson-Morley result. But then, if some supposed physical entity is in principle undetectable, it has no place in Physics and can be discarded.

“...the Sagnac effect demonstrates that depending on the placement of the observer, it is possible to see this variable speed of light and to confound apparent time dilation.”

Yes. Light speed is c relative to an inertial reference frame. For an observer co-moving with a non-inertial (for example a rotating) reference frame, defining measurements of distances and times in terms of that frame, the measured speed of light can indeed be “variable”. The effect is due to the observer’s acceleration.

Note that a rotating “frame” (or more generally, an accelerating frame) in Special Relativity is a curvilinear reference system but that has nothing to do with General Relativity, which is a theory of gravitation! You don’t need General Relativity to explain the Sagnac effect! The Special theory suffices. The effect is fully explicable by referring it to an inertial frame.

Dear Thierry ~

“How can a tangent be taken at one point of a function? Please try to be a bit productive, Eric!”

That doesn’t clarify what you were saying. Under a Lorentz transformation (dx/dt)2 = c2 become (dx’/dt’)2 = c2.

“Why then has Maxwell's equations be doped by the Lorentz invariance?”

They are not “doped” (whatever that means). The symmetry group of a mathematical structure is a rigorously defined concept. Maxwell’s theory is expressed as a set of differential equations; it is is a mathematical structure. It’s symmetry group is the ten parameter “Poincaré group” which contains the “Lorentz group” SO(3, 1) as a subgroup. That is a mathematical fact.

“...a fundamental constant c identified as the speed of propagation of electromagnetic waves." / “Fundamental? On Earth perhaps, but outside the solar system, who knows? ”

Unless or until experiments and observations reveal that “empty space” can have “properties” it is reasonable to assume that μ0 and ε0 are universal constants. Why needlessly introduce complications? Apply Occam’s razor!

" If Galileo’s “Principle” is accepted... " / “Why should it? If light is measured c on Earth, and if it is measured c on a planet in a galaxy far away, which is moving wrt us, what is the value of the speed of light at every place wrt us?” / “Galilei's principle is only locally valid.”

What would be the point of Physics if established physical laws were valid only on the Earth? The uniformity of Nature is the fundamental assumption without which Physics as a science would be meaningless. Yes, it is an assumption. Astronomical observations support it.

There can be no Physics without reasonable assumptions!

“Hence, it is wrong to say: ‘Einstein’s relativity and Lorentz’s aether theory are experimentally indistinguishable. It is therefore expedient for physicists to choose the theory that is conceptually simpler.’ ”

I don't understand the "hence" in that statement! How is what i said "wrong"? What would be the point of introducing unnecessary complications?

"Nature doesn't fit with it."

???

Certainly and without doubt , Lorentz transformation,the real basis of the special relativity theory, in itself has nothing to do with the Maxwell theory.

Dear Emmanouil

I read all contributions and the answers of Eric Lord and F. Leyvraz are really extraordinary. We are lucky to have the chance to learn with so clever persons.

And of course the fundamental postulate of Special Relativity combines the propation of light in empty spaces with the velocity c together with the invariance of the laws of physics on inertial frames, and this is not the case of rotating frames.

Sagnac experiment replaced the fixed inertial frame proposed by Michelson and Morley by a non-inertial frame experiment to conclude what was expected by science, that the laws of physics are non-invariant if one considers non-inertial reference frames. There is no challenge here. This is the reason of "only" 18 citations linked to the article mentioned by Leyvraz. The physicists are not interested in a topic that has already a clear and definitive answer.

Dear Thierry ~

Your argument, essentially, is that Nature might be more perversely complicated than it seems to be. Yes, Galileo might have been mistaken about the equivalence of unaccelerated observers; there might be an aether that we haven’t been able to detect; c might be different in another galaxy, and so on. I cannot prove those statements wrong.

“If I were to suggest that between the Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, nobody would be able to disprove my assertion.” − Bertrand Russell

Theories in Physics proceed from reasonable assumptions based on what is already known, and seek the simplest logically consistent scheme that can account for observed phenomena. A theory is then accepted unless or until experiments reveal anomalies it cannot account for. The theory is then discarded or, far more usually, modified or extended. That is how science works. Attacking the underlying assumptions in the absence of experimental support for the attack is meaningless.

“Please, don't hide yourself behind mathematics...This is about physics”

Mathematics is the language of physics. I concede that blunders can arise when deducing the physical implications of the mathematics underlying a physical theory. That phenomenon is very much in evidence, particularly so in Researchgate discussions. Very careful logical and rational thinking is called for.

“I have proven that it is physically impossible that crossing IRF's would be physically capable to measure the same velocity of light, for the same beam at one single place and time.This disproves the physical possibility of getting Galileo's priciple of relativity for more than one inertial reference frame at once.”

That, I’m sorry to say, is nonsense. See my remark above about careful logical and rational thinking.

“EL: "Maxwell’s theory is expressed as a set of differential equations; it is is a mathematical structure."

“Of course not. Maxwell's theory describes Nature, especially the behavior of charged fast muons in the atmosphere, of accelerated charges at CERN, of atomic clocks with charged components.”

I should have chosen the wording more carefully. Maxwell’s set of equations is a mathematical structure. The behaviour of charged fast muons in the atmosphere, of accelerated charges at CERN, of atomic clocks with charged components are analysed and understood using that mathematical structure. You seem to be “clutching at straws” here.

“The behavior allegedly due to SRT is in fact caused by the retardation of the electric field due to fast motion, like with the sound barrier of supersonic jets. The electric field becomes almost zero in the line of motion and increases perpendicularly on it. This created a strong induced magnetic field that induces a strong Lorentz compression force, pointed inwards the muon, which delays the decay.”

Cite references! Why should such a bizarre scenario be accepted when a far simpler explanation is available?

EL: "Unless or until experiments and observations reveal that “empty space” can have ‘properties’...”

“You try to inverse the requirement of proof.”

No, it’s you who are trying to invert the requirement of proof.

“The Michelson Morley experiment only tried to find the velocity of an universal aether...”

You offer several alternative explanations of the null result. The simplest of those is “light is not carried by the aether.” I accept that unless and until experimental evidence reveals it to be incorrect. In any case, the M-M experiment is not the crucial foundation stone of Special relativity that many claim it to be:

"In my own development Michelson’s result has not had a considerable influence. I even do not remember if I knew of it at all when I wrote my first paper on the subject (1905). The explanation is that I was, for general reasons, firmly convinced that there does not exist absolute motion and my problem was only how this could be reconciled with our knowledge of electro-dynamics. One can therefore understand why in my personal struggle Michelson’s experiment played no role or at least no decisive role." − Einstein 1942

“In every known physical system, the propagation of waves is provided by the properties of the medium.”

That is a false analogy. It is a naive assumption that light waves must be the same kind of thing as sound, ripples on a pond, vibrations of a string, etc.

“So, it is clear that no proof has been given that there is no medium....”

No proof has been given that there is. Again you are trying to invert requirement of proof.

“Raffiniert ist der Herr Gott, aber boshaft ist Er nicht. (God is subtle but he is not malicious)” − Einstein

Respected all,

The speed of light, C, is a fundamental property of empty space (vacuum) and has nothing to do with the state of measuring device even though we compute its numerical value by experiments b'cos there is no other go. Further, C is a property of the empty space and has nothing to do with the state of the space itself! i.e., whether space-time is bending, stretching etc. Therefore, whether one measures C in an inertial frame or non-inertial frame, it's going to be the same.

Just by assuming the existence of a cosmic speed limit, C, it's possible to derive the relativistic mass formula from the definition of force given by Newton, i.e., force is `rate of change of momentum'. (I have a simple minded derivation given in a paper titled `Superlumina Particles' available in RG) After that derivation, if one asks which coordinate transformation yields such a relativistic mass formula, then one ends up with Lorentz transformations for inertial frames.... Since the relativistic mass formula is derived from the definition of force which acts locally on a given mass `m', one can conclude that the same formula is valid locally and the speed of the particle entering the formula should be the local speed. This situation corresponds to non-inertial case. But, in the case of moving mass-less particle (light), its energy-momentum changes at different locations but its speed, C, remains a constant and this corresponds to non-inertial case for light. Moreover, since the energy-momentum is changing, its path need not always lie on a straight line. This is precisely the reason why the bending of light and also gravitational red-shit occurs.

Why Nature requires a Cosmic speed limit in the first place may be totally a different question and everyone may be already aware of it.

Therefore, my conclusion is that, even if the Michelson-Morley experiment is replaced by Sagnac experiment, the end result regarding the speed of light have to be the same b'cos it's independent of any kind of reference frame. In the case of Michelson-Morley experiment corresponding to inertial frame, it's easy to infer the path of light beam. But the same may not be said in the case of Sagnac experiment. This point was beautifully explained by Prof. Eric Lord, "...... A simple calculation shows that, relative to an inertial system, the two beams travel different distances at the same speed c. Why this is so can be understood intuitively by means of a simple diagram illustrating schematically what is happening from the viewpoint of the inertial system...."

Thanking you and best regards ....NG.

I'm not "mocking" anything, Thierry.

Yes, it may well be that "...new concepts, entirely different than the ones that were taught for decades, will shake the minds." But only when those concepts have experimental evidence to support them!

“Galileo's principle of relativity is not applicable.”

Please think more carefully about that and about what you wrote in the paragraph immediately below it. I'm only speaking the truth when I say that it doesn’t make any sense.

You misunderstand what the Principle is. An “inertial frame” is a reference system. Having chosen such a reference system, measured distances and times are expressed in terms of that system. They are not invariants; they will be assigned different numerical values with respect to a different choice. The fundamental postulate of SR is that the speed of light (a distance divided by a time) is an invariant − the same for any choice of inertial reference system. (If you Google “meter definition” you will see that that has been accepted by the international community of physicists as true by definition.)

“...as I explained, that SRT can only be meant for light signals between IRF's, because if there were a Fitzgerald-Lorentz contraction, all the IRF's would get contracted rulers, which is physically irrelevant.”

Light, like any other physical entity, travels between an source and a receiver, not “between inertial frames”. IRFs don’t “get contracted rulers”. According to Einstein's SR (as opposed to Lorentz's aether theory) Fitzgerald-Lorentz contraction is a property of observations, not of material objects. So is “time dilation” and the misguided notion of “relativistic mass” that has infested many textbooks.

Maxwell’s equations (in their standard, generally accepted form) have not been “infested by the Lorentz invariance”. They simply are Lorentz-covariant equations! There’s no point in trying to deny that! Thus Maxwellian electrodynamics complies with Galileo’s Principle, but only if the transformations between inertial reference systems are the Lorentz transformations, not if they are the Galilean transformations or some other transformation laws.

“The behavior of the fast muons in the atmosphere and in the CERN accelerator is already contained in the original Maxwell equations.”

Yes, but why is that? It it is so because Maxwell’s theory is Lorentz covariant.

Please forgive me if I don’t wish to continue this argument. Researgate discussions are taking up too much of my valuable time.

Kind regards

~ Eric

quote:

"What Napoleon wrote for history can also apply here : "History is a succession of lies, agreed upon" .

I second that. Thumps up!

SRT is just a convention really, whereas Sagnac intereferometry is a real life useful application navigational tool used in airplanes and many other applications.

Give me a real life application of SRT? apart of producing tons of scientific bubledegoo...

BTW, I can't find everywhere the original publication of Sagnac expariment :

G. Sagnac

C. R. Hebd. Séances Acad. Sci. Paris, 141(1913), pp. 1220-1223

and

G. Sagnac

C. R. Hebd. Séances Acad. Sci. Paris, 157(1913), pp. 708-710

Why?...

just the in favor of SRT, the Sagnac effect and its interpretation by Paul Langevin

His opinion is biased, I want the original thing of the creator himself!

Dear Thierry ~

Numerous experiments have been carried out to test the validity of the predictions of SR (http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html). Many of them are well-known, so there is no need for me to discuss them here. I need only state my considered opinion that so far, within the limits of its applicability and within the limits of experimental error, there has been no reason to suspect that there is anything wrong with SR.

Most convincing to me is that SR is tested in high-energy physics every time the results of accelerator experiments are interpreted − literally millions of observations that have rendered the theory well-nigh unassailable. Physics (theoretical and experimental) has come a long way since 1905. Present knowledge and understanding of elementary "particles", developed throughout a century, has been based on acceptance of SR. Field equations are formulated as Lorentz-invariant equations. Thus SR has become an essential foundation stone of modern physics. Were SR not essentially correct, all that would come tumbling down!

The symmetry group of Maxwell's electromagnetic equations is the Lorentz group SO(3, 1). Dirac's field equation for the electron is invariant under Lorentz transformations SO(3, 1). (That's how Dirac arrived at it....) Feyman's Quantum Electrodynamics (QED) deals with the interaction between electrons and photons. SR was thus an ESSENTIAL INGREDIENT in the development of QED. The predictions of QED are confirmed by experiments with astonishing precision. The anomalous magnetic moment of the electron, for example, accurately predicted to twelve decimal places!

How is THAT to be explained, if SR is "wrong"??

[copied and pasted from my article https://www.researchgate.net/publication/305260245_Notes_on_the_Meaning_of_Einstein's_Special_Theory_of_Relativity]

Thierry ≪SRT is a thought experiment, without any evidence for fast masses...≫

Here is one of the thoughts. Not the lightest one to think; it weighs some 7000 tonnes. Over the years, it has witnessed some 1015 collisions between pretty fast masses.

You are free to think otherwise, like you are free to think the Earth is flat. After all, it is all just thought experiments...

In fact it has witnessed many, many more collisions than that... And it's about to record more...

Stam ≪many, many more collisions than that... ≫

I was trying to be conservative, while providing an easy-to-remember number:

"The LHC has far exceeded its target for 2017. It has provided its two major experiments, ATLAS and CMS, with 50 inverse femtobarns of data, i.e. 5 billion million collisions. The inverse femtobarn (fb-1) is the unit used to measure integrated luminosity, or the cumulative number of potential collisions over a given period."

By billion they here mean 109.

Fig. 1 Sagnac Experiment

Title

Special Relativity: A theory Not of relative frames of reference but for fictional frames of reference

Dear All,

The SRT is just a convention, and without any practical applications for human civilization. On the other hand , Sagnac interferometer has many everyday real life applications.

Also you are missing some important information which is kept deliberately on the dark, about the original Sagnac experiment.

Do you really think he rotated the experiment only clockwise and did not repeated the process at the counter clockwise rotation?

If you think he just measured the other beam to be in favor...you are mistaken!

The fringes were at different spacing than the CW rotation proving therefore that light speed was controlled by an directional aether wind or flow across its experiment apparatus. So now this has nothing to do with fictional frame of references. This is reality.

And why should I really be concerned of what observer B is seeing? his frame is FICTIONAL GOD LIKE FRAME OF REFERENCE... (Fig.1)

...light in the experiment is not at frame B but in frame of reference A (reality). Light is not bouncing on mirrors on frame B? The mirrors are at frame A located. Therefore if there is a time difference in the light beams caused due aether this is due different light speeds since observer A he sees no different path distances for the light beams, they are the same. So the variable light speed is the reality and therefore SRT is fictional and not real theory.

So, if you like it or not frame A is the real frame because there is where the action takes place and frame of reference B is a FICTIONAL FRAME OF REFERENCE. AN ILLUSION.

Unfortunately for observer B he sees an illusion with contracting space and time and all these SRT bubbledigoo!

The only truth about SRT is that we live our lives (observers) in many cases, inside an illusion, this is very true and relative to reality, I submit.

Kind Regards,

Emmanouil Markoulakis

TEI of Crete

Greece

For the umpteenth time-what any observer sees/measures are the invariant quantities, so it doesn't make sense going on and on about quantities that aren't invariant under Lorentz transformations, when discussing special relativity.

Nor does it make sense talking about illusions, since the word doesn't mean anything more than what someone might expect-not having done any consistent calculation, which is the only thing that matters.

http://insti.physics.sunysb.edu/~siegel/warning.html

http://insti.physics.sunysb.edu/~siegel/quack.html

http://insti.physics.sunysb.edu/~siegel/parodies/%F0%9F%98%9D.html

@Stam Nicolis

Sir, do the subject please.

Do you deny that frame B of fig.1 is fictional only inside our minds and therefore an illusion? And if yes, can science be build on illusions?...

SRT I submit is a fictional theory with imaginary space and time contractions which is trying to explain illusions.

What are your arguments on the above statement?

@ Thierry De Mees

quote:

"Lorentz covariance is injected in the Maxwell equations without understanding Maxwell's equations and without any need whatsoever, since the Liénard-Wiechert equations already account for them.

O tempora, o mores! Are there no honest people any more?

With best regards,

Thierry De Mees"

That is very true!... As I said it is a fictional theory overrated which has lead however to many today misconceptions and dead ends holding progress back and really inhibiting indoctrinated scientists to reach their full potential.

Emmanouil

Dear Thierry ~

“...cannot even reply to...the reasoning revealing the fallacy of Galileo's relativity for more than one inertial reference frame.”

I couldn’t reply to that “reasoning”, simply because I didn’t understand it. You said “I have proven that it is physically impossible that crossing IRF's would be physically capable to measure the same velocity of light, for the same beam at one single place and time.” That is unintelligible to me, so how can I be expected to respond to it?

Which aspects of my reasoning have you given serious consideration to? In your view I’m a “naive priest”, my knowledge of Relativity is my “unsubstantiated opinion” and is “irrelevant and beside the point”. (Which of us is the one who’s “mocking”?)

Your assertions that “... SRT can only be meant for light signals between IRF's, because if there were a Fitzgerald-Lorentz contraction, all the IRF's would get contracted rulers, which is physically irrelevant”, and “SRT is a thought experiment, without any evidence for fast masses”, etc. reveal to me that you have very little real understanding of what Relativity theory is actually about. (Incidentally, the F-L contraction is a property of observations, not of material objects and "relativistic mass" is a prevalent misunderstanding: energies are velocity dependent, masses are not, in SR as in Newtonian dynamics.)

Have you wondered why the results of the calculations of Liénard and Wiechert (for a single moving charge in an electromagnetic field) foreshadowed (and, as you express it “explained”) some aspects of Special Relativity? That was a consequence of the fact that Maxwell’s theory was already a fully Relativistic theory (a fact that you have tried to deny in your responses to me!).

SR is about much more than the motion of a single moving charge in an electromagnetic field! Your remark that "SRT is nothing more: the description of the deformation of light beams between inertial reference frames" is ludicrous. SR offers a complete system of dynamics, deriving the modifications to the Newtonian concepts of energy and momentum when very high velocities are involved, modifications that are necessary if those concepts are to be consistent with Maxwellian electromagnetism. The result is a unified conceptual scheme in which the Principle that “all inertial reference systems are equivalent for the expression of physical laws” (or, stated mathematically: “All physical laws are expressible in a form that is invariant under SO(3,1)) is fully realized.

That is SR. That is what high energy physics has confirmed experimentally beyond any shadow of doubt (quite apart from the many other kinds of experiments that have confirmed its validity).

(Only the physics of gravitation is left out of the unification. But that, as they say, is another story....)

For what is worth it, the original Sagnac papers and their translations in English:

http://gsjournal.net/Science-Journals-Papers/Author/549/Georges,%20Sagnac

Dear Thierry ~

“Do we agree that SRT asserts that an IRF will always measure the speed of light as being “c” in all circumstances?”

Yes.

“Do we agree that two IRF's can measure the same light beam?”

Yes.

“Do we agree that two IRF's can cross in opposite directions?”

Yes.

“How can it physically be that such two IRF's can measure the same value “c” of the same beam?”

They measure dx/dt = c and dx’/dt’ = c. Which can be so if and only if x and t are related to x’ and t’ by a Lorentz transformation (that of course is what leads to the derivation of the Lorentz transformations). A Galilean transformation (with t= t’) doesn’t allow it.

“So, can you give some more details of what exactly it “reveals to you”, technically?”

It reveals that you haven’t understood that a moving rod only appears shorter than it is because measuring the length of a moving rod requires locating the positions of its ends “simultaneously”. The apparent contraction is a consequence of the fact that according to SR “simultaneity” is different for different observers. Your mention of “fast masses” tells me you’ve been misled by the idea that E = mc2 applies to moving matter, wheras it applies only to matter at rest. I can’t blame you for that; the misleading concept of “relativistic mass” is quite prevalent in the literature of SR − I myself once thought that “relativistic mass” was a valid physical concept.

“Can you explain how it comes that Einstein's paper mentions masses as being changed, according to the interlinked alleged Fitzgerald-Lorentz length contraction and alleged time dilation?”

Einstein’s physical interpetations of the implications of his own theories were sometimes wrong! We are all obliged to think things through for ourselves from basic principles, not from “appeals to authority”. The Lorentz transformations are applied to reference systems. They don’t change the physical reality described in terms of those systems.

“Can you explain how it comes that charges cannot be further accelerated by CERN?”

Because the energy of a particle increases with velocity, and according to SR, tends to infinity as velocity approaches c. As you pointed out to me, the Liénard–Wiechert calculations lead to the same conclusion. But there is no conflict between the Liénard–Wiechert explanation and the SR explanation.

“Can you explain why the original Liénard-Wiechert equations of electromagnetism, established in 1898, which already show that the retardation of light causes the electric fields to be distorted by speed, explaining the CERN results and the fast muons results, have been changed after 1905 by relativity-proponents with the Lorentz invariance?”

“Can you explain why Maxwell's equations, as written in 1884 by Oliver Heaviside, have been changed after 1905 with the Lorentz invariance, while the original Liénard-Wiechert equations, deduced from Maxwell's equations, already account for the charges' values caused by fast speeds?”

As I said above, there is no conflict between the Liénard-Wiechert explanation and the SR explanation. Calculations based on the Lorentz transformations are adopted because they are far simpler. And SR goes far beyond the very special problem in electromagnetism that Liénard and Wiechert solved. It offers a completely consistent physical theory encompassing electromagnetism and (modified) Newtonian dynamics. Physics isn't a miscellaneous collection of ad hoc solutions to particular problems.

“When you have answered all these questions, we can talk about your saying: “Your remark that "SRT is nothing more: the description of the deformation of light beams between inertial reference frames" is ludicrous.”

It’s not my job to teach you Relativity theory.

This is meant as friendly advice, not mockery:

Study the Relativity literature in more depth. And think for yourself, don’t blindly accept everything you read just because some “eminent physicist” said it. Also look into the so-called “paradoxes” and the assertions of “anti-relativists” and play detective; search for the logical errors. A lot can be learned by doing that.

Kind regards

~ Eric

Too many, meaningless, words. The only information is contained in the invariant quantities. For electromagnetism these are the Lorentz invariant and gauge invariant quantities.

How these quantities are computed doesn't matter-because it's possible to calculate them in many different ways and to check that they're Lorentz invariant and gauge invariant in many ways, that are equivalent. So the methods are much less interesting than the results.

The confusion arises because people don't realize that they're discussing non-invariant quantities-that, by themselves, don't mean anything.

Dear Emmanouil,

The answer to your question is “No” because the basic assumptions of the theory of special relativity are not satisfied in the experiment. Namely the system is not inertial and the light travels in a certain environment different that vacuum.

I have also a remark concerning geometrical aspects of the problem. We can start with a quote from the letter written by J. Bolyai to his father, on November 3, 1823: “I created a new, different world out of nothing.” Today, we do not doubt that space in which we are functioning is not Euclidean. When I look at the theory of special relativity, I switch my reasoning to the one respecting hyperbolic geometry; this is perfectly acceptable.

As far as the Sagnac interferometer is concerned we use it in many fields ranging from inertial navigation to geophysics (for sensing the speed of rotation of our planet and even for registering the earthquakes). Very often, researchers benefiting from this ingenious device do not pay attention to the fact that Sagnac in 1913 was motivated by the desire to question the validity of a certain philosophical vision of time and space. Shortly after the original experiments, P. Langevin presented an explanation of the results obtained by Sagnac. For further comments please see the paper published recently in the “Comptes Rendues Physique”:

https://www.sciencedirect.com/science/article/pii/S1631070517300907

The synthesis of the findings is as follows:

Regards,

Janusz

Dear Professor Janusz Pudykiewicz ,

You arguments are well noted in this thread here by others and thank you for your expert analysis.

However, it is not more in my interest to proof anything here and argue on SRT. If you have read my previous posts I have explained why SRT is a fictional theory calculating fictional phenomena in fictional frames of reference which have little relation with reality. Threfore SRT is the theory of illusions.

Kind Regards,

Emmanouil

Dear Thierry ~

(1) “My question was 'physically', not 'mathematically'.”

That is your problem. The appropriate language of physics is mathematics. Debating with imprecisely-defined words is a source of confusion. If you are objecting to dx/dt = c and dx’/dt’ = c because that’s “mathematics”, then I throw up my hands in despair! But I’ll try to clarify in words anyway. In principle, each observer can set up synchronized clocks at two fixed points, measure the distance and the time taken for light to pass between them. But the pair of clocks employed by the two observers cannot be the same for the two observers, because “fixed”, “distance”, “time” and “synchronized” have different meanings in different inertial frames.

The answers to your questions have just been concisely expressed by Stam Nichols. There are observer-dependent (or reference-system-dependent) quantities and invariant quantities. The former are not properties of objectively real physical phenomena; the latter are. You should be able to answer all your questions for yourself if you bear that in mind and make an effort to undertand what I’ve already said to you.

(2) and (3) What you’ve said here is correct.

Clearly, an observer cannot know anything about the data acquired by another observer unless information is transmitted. That’s not SRT its just common sense. However, the information doesn’t necessarily have to be transferred by “light signals”.

(4) Liénard and Wiechert investigated and solved the problem of a charge moving in an electromagnetic field and interacting with it. The details revealed are of considerable interest. However, they cannot be in conflict with SRT as you are trying to claim, because Maxwellian electromagnetic theory is an integral part of SRT in its full form. As I’ve tried to clarify, the fully developed form of SRT is far more than some rigmarole about “frames” and “light rays” (that's just "Relativity 101") - it’s a complete classical physical theory that subsumes electromagnetism and dynamics.

I’m sorry, Thierry, I can’t keep this up. It’s taking up too much of my time and is becoming repetitive. I already told you: it’s not my job to teach you Relativity.

Regards

~ Eric

Dear Eric

I completely agree with you! In fact all physicists I presume agree with you."

"The appropriate language of physics is mathematics. Debating with imprecisely-defined words is a source of confusion."

I like to say the following to my students: ask 10 people to describe in words the Dirac equation and you will get 10 different descriptions; ask 10 people to write the mathematical formulation of the Dirac equation and you will get a unique expression. The first mode of expression is imprecise and source of confusion. The second is accurate.

I like RG, but many discussions here, based many times on an imprecise language, giving rise to shallow discussions from the scientific point of view, is a bit tiresome. But I admire your patience in trying to bring your experience and knowledge to this forum.

linguistic description always precedes mathematical description even we like it or not... specially when they are new things to say which are not yet formulated in mathematics.

Dear Thierry ~

Get back to me when you've learned what Special Relativity Theory is.

Dear Emmanouil ~

There’s an indispensible level of thinking about and understanding Physics that precedes the words and the mathematics:

“The words of the language, as they are written or spoken, do not seem to play any role in my mechanisms of thought. Conventional words or other signs have to be sought for laboriously at a second stage.” — Einstein

Dear Emmanouil

You are completely mistaken in your statement. You are confusing two steps of the scientific method, the step of the observation of a phenomenon and that step of the logical elaboration of a hypothesis about the phenomenon, with the verbalization or "explanation" of the phenomenon in terms of words.

The scientific explanation of a phenomenon requires the use of logical cognitive tools. And there is no formal structure more accurate and powerful than mathematics. It is for this reason that mathematics is considered by the scientists the language of physics.

But this is Acacian. That is, this conception reaches all the precepts accepted by the international scientific community.

You also did not realize that the Sagnac experiment replaced the fixed inertial frame experiment proposed by Michelson and Morley by a non-inertial frame experiment. And he evidently came to the conclusion expected by science: that the laws of physics are non-invariant if one considers non-inertial reference frames. There is no challenge here.

About the Sagnac effect you can read a very interesting paper recently published:

Author: GianniPascoli

Article The Sagnac effect and its interpretation by Paul Langevin

As you know, In 1899, Georges Sagnac had developed a theory of the existence of a motionless mechanical aether. His aim was to explain within this theoretical framework all the optics phenomena, and especially the Fresnel–Fizeau experiment for the drag of light in a moving medium. In 1910, he conceived a rotating interferometer for testing his ideas and to see the optical whirlwind effect, as he called it . The effect discovered by Sagnac was published in the Comptes rendus de l'Académie des sciences in 1913.

You should take into account in your analysis that the Sagnac experiment was carried out before full confirmation in other experiments of the conclusions of the crucial experiment of Michelson and Morley. The scientific community as a whole only accepted relativity after some time.

Should also remember that special relativity has successfully passed tests of thousands of experiments of all types. So today it is clearly no longer questionable but in the begining of 20 century the situation was different. There is no conspiracy theory that has survived the success of special relativity and general relativity. The clamor in France in that period around Sagnac was only one of them.

Langevin derived the effect from the General Relativity. The Sagnac effect was already derived from special relativity by Von Laue one year before Langevin.

In short, the main argument of Langevin is that the Sagnac experiment involves a first order dependence on v/c contrary to the experiment of the experiment of Michelson–Morley, which involves a second-order effect.

He starts from the Minkowskian metric associated with the central observer, denoted by O, located at the center of the rotating disk.

From the point of view of the inertial observer O, the source of ligth, the detector and the non-inertial observer NIO are located at the same place.

He used the cartesian coordinates and performed a global transformation of the coordinates in order to impose a new coordinate system that accompanies the disk in its rotation and he obtains a metric with mixed terms that is not anymore relativistic invariant, source of the impossibility of synchronizing clocks, uniformly distributed around the periphery of the disk and connected thereto (a relativistic phenomenon which is the essence of the Sagnac effect).

He is presently frequently cited by the engineers working on devices such as for instance ring-laser gyroscopes which operate on the principle of the Sagnac effect.

If you do the mathematical deduction of effect you will come to the same conclusions as those great scientists, Langevin and Max Von Laue.

You can see here a practical example of how wrong you are in neglecting the role of mathematics in science. Do the math!

Dear Thierry ~

https://www.flickr.com/photos/ericlord/42358388261/

Dear Demetris ~

" ask CERN to accelerate a non charged particle: I have done it several years from now, nobody answered. they continue their ridiculous circle experiments with charged only particles "

ROFL (-:

You do realize don't you, that neutral particle are among the products of the collision processes that CERN was set up to investigate and that their energies and momenta are those given by SRT?

Eric (to Thierry) ≪Get back to me when you've learned what Special Relativity Theory is.≫

I wouldn't hold my breath while waiting... :-D

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• nobody cares if an experiment disproves relativity theories, they are made for believers: a believer will never oppose his 'guru'>
• does anybody care if relativity is theoretically disproved? I am asking because I did that in my work

Kare,

https://arxiv.org/pdf/1610.08188.pdf

is there any reason why c should not be isotropic in that experiment?

They simply showed that c is isotropic in that conifguration to 10^-28 uncertainty.. It is not a general finding, it is naive to think that that such experiment has a general validity.

Dear Paul

Your statement about believers has no meaning in the scientific world. With respect to the Sagnac experiment, Longevin and Max Von Laue, for instance, two of the greatest scientists in the story have derived the Sagnac effect and have proven mathematically what was physically going on. There is no mistery, no chalenge and no conclusion linked to any conspiracy theory associated to the Sagnac effect. Do the math! You will reach the same conclusion.

Hi Thierry

As allways you think you are the only person in the world that knows the true about science. Congrats and best regards.

Hi Stefano

I hardly can understand your statement: "there any reason why c should not be isotropic in that experiment.?"

Do you mean and electromagnetic wavefront linked to a point source?