Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Lorenz covariance vs proofs of relativity theory

  1. Mar 16, 2015 #1
    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 Im right there is major simplification in learning and presenting of relativity theory which is simply not true, despite being the only mainstream view.
     
  2. jcsd
  3. Mar 16, 2015 #2

    Dale

    Staff: Mentor

    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.
     
    Last edited: Mar 16, 2015
  4. Mar 16, 2015 #3
    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"?
     
  5. Mar 16, 2015 #4
    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
     
  6. Mar 16, 2015 #5

    PAllen

    User Avatar
    Science Advisor
    Gold Member

    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').
     
  7. Mar 16, 2015 #6

    Dale

    Staff: Mentor

    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.

    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.
     
  8. Mar 17, 2015 #7
    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.
     
    Last edited: Mar 17, 2015
  9. Mar 17, 2015 #8

    PAllen

    User Avatar
    Science Advisor
    Gold Member

    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?
     
  10. Mar 17, 2015 #9
    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).
     
    Last edited: Mar 17, 2015
  11. Mar 17, 2015 #10

    PAllen

    User Avatar
    Science Advisor
    Gold Member

    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.
     
  12. Mar 18, 2015 #11
    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)
    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
     
  13. Mar 18, 2015 #12
    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.
     
    Last edited: Mar 18, 2015
  14. Mar 18, 2015 #13
    Last edited: Mar 18, 2015
  15. Mar 20, 2015 #14
    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?
     
  16. Mar 20, 2015 #15

    Dale

    Staff: Mentor

    I certainly wouldn't agree with that. The Sagnac effect is not only handled by SR, it is predicted by SR.
     
  17. Mar 20, 2015 #16
    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.
     
  18. Mar 20, 2015 #17

    Dale

    Staff: Mentor

    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?
     
    Last edited: Mar 20, 2015
  19. Mar 20, 2015 #18
    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.
     
  20. Mar 20, 2015 #19

    wabbit

    User Avatar
    Gold Member

    Rovelli in his 'Relational Quantum Mechanics' paper suggests, half in jest perhaps, an even stronger formulation :
     
  21. Mar 23, 2015 #20
    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).
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Lorenz covariance vs proofs of relativity theory
Loading...