Lorenz covariance vs proofs of relativity theory

[SpiderET]

I have been studying history of relativity theory and now it seems to me, that it is wrong to automatically assume that proofs of Lorentz covariance are proofs of Special relativity theory.

It seems to me, that there is broader group of theories, that are compatible with Lorentz covariance but are not compatible with Special relativity theory.

You could divide these theories in two major group. One group is Special relativity theory and similar theories, which assume, that there is no preferred frame of reference. The second major group are theories who are consistent with Lorentz covariance, but are based on preferred frame of reference. Most known member of this group is Lorentz ether theory. I know, this is not a mainstream theory and the point is not to try promote Lorentz ether theory.

The main point here is if this second group of theories with preferred frame of reference was never proved wrong that leads me to logical conlusion that experiments which are mentioned as proofs of Special relativity theory are actually not proofs of Special relativity, but only proofs of Lorentz covariance. But if I am right there is major simplification in learning and presenting of relativity theory which is simply not true, despite being the only mainstream view.

 

[Dale]

Typically LET and SR are not considered to be different theories, but just different interpretations of the same theory (Which is usually called SR also). So the measurements supporting the theory support all interpretations.

 

[harrylin]

I have been studying history of relativity theory and now it seems to me, that it is wrong to automatically assume that proofs of Lorentz covariance are proofs of Special relativity theory.

It seems to me, that there is broader group of theories, that are compatible with Lorentz covariance but are not compatible with Special relativity theory.

You could divide these theories in two major group. One group is Special relativity theory and similar theories, which assume, that there is no preferred frame of reference. The second major group are theories who are consistent with Lorentz covariance, but are based on preferred frame of reference. Most known member of this group is Lorentz ether theory. I know, this is not a mainstream theory and the point is not to try promote Lorentz ether theory.

The main point here is if this second group of theories with preferred frame of reference was never proved wrong that leads me to logical conlusion that experiments which are mentioned as proofs of Special relativity theory are actually not proofs of Special relativity, but only proofs of Lorentz covariance. But if I am right there is major simplification in learning and presenting of relativity theory which is simply not true, despite being the only mainstream view.

If you really studied the history of relativity (some of your phrasings make me wonder if you read Wikipedia instead of the historical literature), you likely discovered that Lorentz taught SR as well as GR but never changed his interpretation - and it looks like Einstein changed his mind more than once. As SR happens to be independent of interpretation, it doesn't matter. However, interpretations can somewhat "colour" the descriptions, and as a result the teaching of SR is sometimes subtly suggestive in a way that is unwittingly misleading, as if the suggested interpretation is SR itself. Is that what you mean with "a major simplification"?

 

[SpiderET]

If you really studied the history of relativity (some of your phrasings make me wonder if you read Wikipedia instead of the historical literature), you likely discovered that Lorentz taught SR as well as GR but never changed his interpretation - and it looks like Einstein changed his mind more than once. As SR happens to be independent of interpretation, it doesn't matter. However, interpretations can somewhat "colour" the descriptions, and as a result the teaching of SR is sometimes subtly suggestive in a way that is unwittingly misleading, as if the suggested interpretation is SR itself. Is that what you mean with "a major simplification"?

If I understand it right, the quotations are the same, but there is still a big difference, if in reality there is some preferred frame or not. So there are two possible descriptions of reality and this is not a mere interpretation issue but the fundamental question which is until now undecided by experiments.
My primary source about history of relativity is not Wikipedia, but:
http://philsci-archive.pitt.edu/987..._and_Lorentz's_Ether_Theory_name_included.pdf

 

[PAllen]

To me it is a pure interpretation issue until there is at least a conceptually possible experiment to distinguish. The QM interpretations remain that unless there is an experiment to distinguish them; if there is, they become competing theories, with some being excluded when such an experiment is performed. The main difference between the SR interpretations and QM interpretations is that many more physicists write papers about the latter.

I guess one other difference is that you cannot really say some QM interpretation is strictly a subset of another. In the case of LET, you can state that it is strictly a subset of the more common interpretation in that it is in every way equivalent to starting any SR analysis by picking a single inertial frame (and naming this frame 'real').

 

[Dale]

If I understand it right, the quotations are the same, but there is still a big difference, if in reality there is some preferred frame or not. So there are two possible descriptions of reality and this is not a mere interpretation issue but the fundamental question which is until now undecided by experiments.

I assume that you meant "equations" instead of "quotations".

This is exactly what an interpretation is: an alternative description about what is happening "in reality" while using the same equations and thus generating the same experimental predictions. Although you say it "is not a mere interpretation issue" everything else that you wrote exactly describes an interpretation issue. I agree with PAllen.

My primary source about history of relativity is not Wikipedia, but:
http://philsci-archive.pitt.edu/987..._and_Lorentz's_Ether_Theory_name_included.pdf

Note that your source is a philosophy site. Philosophy tends to concern itself primarily with interpretation issues, so the fact that this is your source further indicates that it is in interpretation issue. I haven't yet read the specific paper, but just be aware of the fact that you are looking into the philosophical literature and so you will get philosophical discussions.

 

[harrylin]

If I understand it right, the quotations are the same, but there is still a big difference, if in reality there is some preferred frame or not. So there are two possible descriptions of reality and this is not a mere interpretation issue but the fundamental question which is until now undecided by experiments.

My primary source about history of relativity is not Wikipedia, but:
http://philsci-archive.pitt.edu/9871/1/On_the_EE_between_SR_and_Lorentz's_Ether_Theory_name_included.pdf

SR is based on two postulates which refer to definitions that are independent of interpretation - it's purely about observables. That's why Lorentz and Einstein agreed on SR although they disagreed much of the time about interpretations.

Many people, including the writer of the paper you base your opinion on, misunderstand SR in the way you noticed. Looking at the references it's by definition a "tertiary" source like Wikipedia; in order to really study something it's necessary to study the originals (the "primary sources"). If you read those, you will search in vain for any paper in which Lorentz proposes an "ether theory" or a "preferred frame" (which meaning is often misunderstood).

Interestingly one of the references is to a paper by Ives. Ives was one of those people who must have been taught SR as representing an anti-Lorentz interpretation; he was a bit like a Don Quichotte fighting windmills. But one day he must have realized that SR is interpretation-neutral, for he next wrote a paper on deriving SR from the conservation laws.

PS I quickly browsed though your source and while it gets of course many things right, I also immediately noticed a few misconceptions, and it effectively shoots at a straw man. The author even ignores (despite citing it!) that according to Lorentz the "theories" that he sets up against each other, are different presentations of the same theory (Einstein and Lorentz agreed on that). Still it can serve as a reasonable introduction to the history of SR.

 

[PAllen]

...
Many people, including the writer of the paper you base your opinion on, misunderstand SR in the way you noticed. Looking at the references it's by definition a "tertiary" source like Wikipedia; in order to really study something it's necessary to study the originals (the "primary sources"). If you read those, you will search in vain for any paper in which Lorentz proposes an "ether theory" or a "preferred frame" (which meaning is often misunderstood).
...

That's interesting in that all secondary sources I've read claim otherwise, and point to:

"The Relative Motion of the Earth and the Ether", Lorentz (1892) as an example of such papers.

However, I am unable to find an accessible copy of this paper to check what it actually say.

Do you know of any such accessible link?

Can you explain your point of view in reference to this paper?

 

[harrylin]

That's interesting in that all secondary sources I've read claim otherwise, and point to:

"The Relative Motion of the Earth and the Ether", Lorentz (1892) as an example of such papers.

However, I am unable to find an accessible copy of this paper to check what it actually say.

Do you know of any such accessible link?

Can you explain your point of view in reference to this paper?

I have a hard copy of that paper (Dutch version), and I now had a quick look at it again (yes I do make mistakes). He there refers to Maxwell's and Fresnell's theories to discuss MMX and the contraction hypothesis; I do not see mention of an "ether theory".
The paper that the OP's source refers to is Lorentz's theory of 1904. That theory had no name yet ("the proposed theory"), and Lorentz refers there to his old theory (the one that emerged after 1892) as the "theory of electrons".

Lorentz's new theory was rapidly referred to as the theory of Einstein and Lorentz, or "Lorentz-Einstein theory". This is also correctly mentioned in the OP's reference.
Some years ago I searched where "Lorentz ether theory" may have originated, and the earliest mention of it that I found was a denigrating remark by Minkowski (and I'm pretty sure that it was about the old theory of Electrons).

 

[PAllen]

I have a hard copy of that paper (Dutch version), and I now had a quick look at it again (yes I do make mistakes). He there refers to Maxwell's and Fresnell's theories to discuss MMX and the contraction hypothesis; I do not see mention of an "ether theory".
The paper that the OP's source refers to is Lorentz's theory of 1904. That theory had no name yet ("the proposed theory"), and Lorentz refers there to his old theory (the one that emerged after 1892) as the "theory of electrons".

Lorentz's new theory was rapidly referred to as the theory of Einstein and Lorentz, or "Lorentz-Einstein theory". This is also correctly mentioned in the OP's reference.
Some years ago I searched where "Lorentz ether theory" may have originated, and the earliest mention of it that I found was a denigrating remark by Minkowski (and I'm pretty sure that it was about the old theory of Electrons).

Well, forgetting names (which are chosen by others), if this paper is discussing how to get Fresnell's theory (which was an ether theory with ether drift) and Maxwell's theory (as previously often interpreted to hold in standard form only in the ether frame; Lorentz, around this time [I believe] had found the Lorentz transforms to fix this via local time.]) to be consistent with MMX via a length contraction hypothesis (that bodies moving relative to the ether are contracted), then I would certainly call that an ether theory. I would call it the genesis of what is now called LET (but that is a name Lorentz would never use, any more than Einstein would name SR "Einstein Relativity Theory".

At around this time we had Lorentz saying:

- Maxwell's equations hold in frames moving relative to the ether if you use local coordinates related to the ether frame via the Lorentz transform (of course, he didn't call it that).
- Bodies moving relative to the ether are length contracted.
- As this line of theory evolved, it became empirically indistinguishable from SR with any interpretation which says there is no ether by generalizing the EM justification of length contraction with the idea that the ether frame could never be detected. This, then, requires all physical theories to be Lorentz invariant.

 

[Histspec]

That's interesting in that all secondary sources I've read claim otherwise, and point to:

"The Relative Motion of the Earth and the Ether", Lorentz (1892) as an example of such papers.

However, I am unable to find an accessible copy of this paper to check what it actually say.

Do you know of any such accessible link?

Can you explain your point of view in reference to this paper?

The Dutch original is here:
http://nl.wikisource.org/wiki/De_relatieve_beweging_van_de_aarde_en_den_aether
or in English translation
http://en.wikisource.org/wiki/Translation:The_Relative_Motion_of_the_Earth_and_the_Aether
See also the preface of Lorentz fundamental 1895 paper, where he also specifically presented his aether views:
http://en.wikisource.org/wiki/Trans...tical_Phenomena_in_Moving_Bodies/Introduction

The aether idea was (among other things) still present in his 1904 paper, as Lorentz explained in 1914:
http://fr.wikisource.org/wiki/Deux_Mémoires_de_Henri_Poincaré_sur_la_Physique_Mathématique
http://en.wikisource.org/wiki/Translation:Two_Papers_of_Henri_Poincaré_on_Mathematical_Physics (English translation)

The formulas (4) and (7) are not in my memoir of 1904. Because I had not thought of the direct way which led there, and because I had the idea that there is an essential difference between systems x, y, z, t and x',y',z',t'. In one we use - such was my thought - coordinate axes which have a fixed position in the aether and which we can call "true" time; in the other system, on the contrary, we would deal with simple auxiliary quantities whose introduction is only a mathematical artifice. In particular, the variable t' could not be called "time" in the same way as the variable t...Poincaré, on the contrary, obtained a perfect invariance of the equations of electrodynamics, and he formulated the "postulate of relativity".

Regarding his views after 1904, Lorentz thought of his aether as a "preferred" but experimentally undetectable frame. He wrote in 1910:
http://en.wikisource.org/wiki/Trans...pplication_to_some_Special_Physical_Phenomena

Provided that there is an aether, then under all systems x,y,z,t one is preferred by the fact, that the coordinate axes as well as the clocks are resting in the aether. If one connects with this the idea (which I would abandon only reluctantly) that space and time are completely different things, and that there is a "true time" (simultaneity thus would be independent of the location, in agreement with the circumstance that we can have the idea of infinitely great velocities), then it can be easily seen that this true time should be indicated by clocks at rest in the aether. However, if the relativity principle had general validity in nature, one wouldn't be in the position to determine, whether the reference system just used is the preferred one. Then one comes to the same results, as if one (following Einstein and Minkowski) deny the existence of the aether and of true time, and to see all reference systems as equally valid. Which of these two ways of thinking one is following, can surely be left to the individual.

 

[harrylin]

Well, forgetting names (which are chosen by others), if this paper is discussing how to get Fresnell's theory (which was an ether theory with ether drift) and Maxwell's theory (as previously often interpreted to hold in standard form only in the ether frame; Lorentz, around this time [I believe] had found the Lorentz transforms to fix this via local time.]) to be consistent with MMX via a length contraction hypothesis (that bodies moving relative to the ether are contracted), then I would certainly call that an ether theory. I would call it the genesis of what is now called LET (but that is a name Lorentz would never use, any more than Einstein would name SR "Einstein Relativity Theory". [..]

Apparently you did not see what my comment referred to: I clarified how I guessed from the OP's phrasings that in his historical research he was not basing himself on the historical sources but on later literature (there were also other clues). He/she can learn a lot more from the sources, many of which are now easily accessible.

 

[harrylin]

[..] The aether idea was (among other things) still present in his 1904 paper

Indeed; and I did not suggest otherwise. However:

Lorentz thought of his aether as a "preferred" but experimentally undetectable frame. [..]
http://en.wikisource.org/wiki/Trans...pplication_to_some_Special_Physical_Phenomena

Good point (as they say, "never say never", why did I forget? )

Thanks for the correction!

 

[PhilDSP]

In considering everything that's been posted so far, I wonder if the original poster's question is more revelant to situations that we probably all agree aren't handled by SR, such as the Sagnac Effect for example. Is the original poster asking if, for such situations, could an alternate "interpretation" or theory that is in some way compatible in principle with Lorentz covariance predict an experimental outcome that exceeds that of SR?

Given that most of us here will probably spontaneously answer no, is this a request then to sketch what would have to be proved by experiment?

 

[Dale]

situations that we probably all agree aren't handled by SR, such as the Sagnac Effect for example.

I certainly wouldn't agree with that. The Sagnac effect is not only handled by SR, it is predicted by SR.

 

[PhilDSP]

Okay, I've seen a lot of different explanations about how SR applies or doesn't apply, Maybe that was a poor example of an area not described by SR.

 

[Dale]

Okay, I've seen a lot of different explanations about how SR applies or doesn't apply

Nonsense. This is not a topic of any debate amongst the professional scientific community. The Sagnac effect is a prediction of SR.

You may be able to find crackpots explaining otherwise, but you can also find crackpots explaining that the Earth is flat. I won't ask you to post your references because I would just have to delete them, but I encourage you to look at the credibility of those sources. Ask yourself, would a professional scientist accept them?

 

[PhilDSP]

Of course. I'm most interested in what the "heavy weights" have had to say about that particular issue. But it may be off topic for this OP.

 

[wabbit]

Typically LET and SR are not considered to be different theories, but just different interpretations of the same theory (Which is usually called SR also). So the measurements supporting the theory support all interpretations.

Rovelli in his 'Relational Quantum Mechanics' paper suggests, half in jest perhaps, an even stronger formulation :

We could say – admittedly in a provocative manner– that Einstein’s contribution to special relativity has been the interpretation of the theory, not its formalism: the formalism already existed.

 

[harrylin]

Rovelli in his 'Relational Quantum Mechanics' paper suggests, half in jest perhaps, an even stronger formulation :

That's very provocative indeed: it's quite the contrary and the OP's reference elaborates on that (roughly: SR is Lorentz's theory, stripped of any constructive model).

 

[harrylin]

Okay, I've seen a lot of different explanations about how SR applies or doesn't apply, Maybe that was a poor example of an area not described by SR.

If this has not been sufficiently clarified on this forum, you could start a topic on it. SR applies for sure, however many explanations in the literature are unnecessarily complex.

 

[wabbit]

That's very provocative indeed: it's quite the contrary

How so ? I don't see how it is controversial to say that a significant aspect of Einstein's contribution to Special Relativity was the reinterpretation of the Lorentz transformation, which was already well known. Rovelli's statement simply exaggerates this point - this may be wildly excessive but it doesn't make it contrary.

 

[harrylin]

How so ? I don't see how it is controversial to say that a significant aspect of Einstein's contribution to Special Relativity was the reinterpretation of the Lorentz transformation, which was already well known. Rovelli's statement simply exaggerates this point - this may be wildly excessive but it doesn't make it contrary.

Your citation has not "reinterpretation", but "the interpretation". Perhaps I misunderstood what provocation was meant by that (as I don't know the context), but it suggests to me that Einstein added his own explanation to the formalism. And that is quite contrary to the point that Pablo Acuña L makes on p.33 : "explanations which are absent in Einstein‘s theory of principle". But of course, that's a bit off-topic. Closer to the topic is that perhaps Rovelli confounds "Minkowskian presentation of Einstein‘s theory" (p.32) with Einstein's theory (I guess that Rovelli had Minkowski's interpretation in mind). It's the mix-up between empirical physics and proposed interpretations to which the OP fell victim, and he was by far not alone.

 

[wabbit]

Your citation has not "reinterpretation", but "the interpretation". Perhaps I misunderstood what provocation was meant by that (as I don't know the context), but it suggests to me that Einstein added his own explanation to the formalism. And that is quite contrary to the point that Pablo Acuña L makes on p.33 : "explanations which are absent in Einstein‘s theory of principle". But of course, that's a bit off-topic. Closer to the topic is that perhaps Rovelli confounds "Minkowskian presentation of Einstein‘s theory" (p.32) with Einstein's theory (I guess that Rovelli had Minkowski's interpretation in mind). It's the mix-up between hard physics and proposed interpretation to which the OP fell victim.

I don't think there's any mixup, but those interested will be better off reading Rovelli's paper (http://arxiv.org/abs/quant-ph/9609002) than my interpretations of what it means, so I'll leave it at that.

 

[harrylin]

I don't think there's any mixup, but those interested will be better off reading Rovelli's paper (http://arxiv.org/abs/quant-ph/9609002) than my interpretations of what it means, so I'll leave it at that.

Thanks for supplying your reference - that avoids second-guessing.
I think that you are mostly* right: Rovelli seems to think that Einstein was the first to clarify relativity of simultaneity. The physical meaning of relativity of simultaneity is indeed essential for understanding SR.
Note that everyone agrees on interpretation on that level; it's on a deeper level that interpretations differ.

PS thanks for that paper, it happens to be about a topic that I'm interested in.

*Rovelli does misunderstand something, as he writes there about "paradoxical consequences" of Lorentz's theory

 

[wabbit]

Thanks for supplying your reference

I did that in the first post already, what I added is a hyperlink - which I should have done right away, sorry about that.

Rovelli does misunderstand something, as he writes there about "paradoxical consequences" of Lorentz's theory

No he doesn't. There are exactly two occurences of the string "paradox" in that paper, only one of which relates to SR (my highlighting):

The unease with the Lorentz transformations derived from a conceptual scheme in which an incorrect notion –absolute simultaneity– was assumed, yielding any sort of paradoxical consequences.

 

[harrylin]

[..]. There are exactly two occurences of the string "paradox" in that paper, only one of which relates to SR (my highlighting): [..] "an incorrect notion –absolute simultaneity– was assumed, yielding any sort of paradoxical consequences."

That's what I referred to. Rovelli's misunderstanding of "absolute simultaneity" as it may* have been used by Lorentz looked like contradictions to him - "paradoxes".

That paper hardly touches the topic here, as it is about QM. Pablo Acuña's paper explains different notions of simultaneity; and while it doesn't explicitly mention "absolute simultaneity", it does mention the corresponding notion of "absolute motion".

*with a quick search I only found it used in papers by Dirac and Selleri

 

[wabbit]

Well this is off topic, indeed this paper is about QM, so this will be my last reply here, but no, Rovelli doesn't misunderstand absolute simultaneity, and in this quote he doesn't say it was used by Lorentz.

 

[harrylin]

Well this is off topic, indeed this paper is about QM, so this will be my last reply here, but no, Rovelli doesn't misunderstand absolute simultaneity, and in this quote he doesn't say it was used by Lorentz.

Somehow my clarifications were not clear enough. OK then, here's similarly my last try!

"the Lorentz transformations derived from a conceptual scheme in which an incorrect notion –absolute simultaneity– was assumed, yielding any sort of paradoxical consequences" - Rovelli 2008

The Lorentz transformations were first derived by Lorentz and Poincaré. As implied and somewhat clarified by the OP's reference in post #4, that derivation was not derived from a conceptual scheme that yields contradictions. However, it may look paradoxical for people who misunderstand it.

Compare https://www.physicsforums.com/threads/what-is-the-pfs-policy-on-lorentz-ether-theory-and-block-universe.772224/

That's all.