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Some remarks on Einstein's 1907 paper on Relativity

  1. Feb 8, 2012 #1
    I hope that a short discussion of the history of theoretical development is not too much off-topic here; this is a continuation of a discussion started under another, related topic:

    The paper under discussion: Albert Einstein, "Über das Relativitätsprinzip und die aus demselben gezogene Folgerungen," Jahrbuch der Radioaktivitaet und Elektronik 4 (1907)

    A photocopy of the original paper (in German) can be found online here:

    There are also several English translations available:
    - "On the relativity principle and the conclusions drawn from it," in The collected papers of Albert Einstein. Vol. 2 : The Swiss years: writings, 1900–1909 (Princeton University Press, Princeton, NJ, 1989), Anna Beck

    - H. M. Schwartz, "Einstein's comprehenive 1907 essay on relativity", AJP 45, No.6 and No.9, 1977 (this is a discussion of the paper with an English translation by the author).

    Basing myself on the photocopy of the original German document I found the first translation to be quite reliable in general, but the second translation (of which an apparently illegal copy can be found on internet) strikingly unreliable, despite its noble intentions. As a matter of fact, I searched for the original after I first read that translation and had doubts about its contents.

    While I fully agree about Lorentz's adherence to the PoR, I don't agree with some other comments and I suspect that the disagreement is in part due to the misleading translation on which those comments are based. In particular, Schwartz has Einstein introduce the main part of his paper as follows:

    How do unsuspecting readers understand that sentence? Perhaps such readers would tend to think that Einstein there sets out to combine a theory of Lorentz - perhaps the one of 1904 - with "the theory of relativity" - perhaps his own paper of 1905? However, smart readers might wonder why on earth Einstein would want to do such a thing. :wink:

    I will welcome confirmation of such a first interpretation, as that would help to stress how subtle errors can cause huge misunderstandings.
    Also alternative interpretations (but please, not yet by those who are already better informed!) will be interesting.
    More later. :tongue2:
  2. jcsd
  3. Feb 8, 2012 #2


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    The issue we were discussing in the other thread was whether Einstein referred to Lorentz's ideas as a separate "theory" from his own. I referred to that paper (since you earlier referenced it) as an example where Einstein used the word "theory" when talking about Lorentz ideas (or whatever you want to call them if they aren't a theory) in the same sentence with his own theory of relativity. You complained that I was quoting an inferior translation. So why don't you quote from the translation that you consider to be quite reliable and provide your own translation so that I can see what you are talking about?

    The passages in question are the first two paragraphs on page 513 starting with the word "In" of this unreliable translation.
    Last edited: Feb 8, 2012
  4. Feb 8, 2012 #3
    Thanks for the confirmation - you interpret those words just as I did the first time that I saw that passage. And it determines the interpretation of the whole section that follows.

    However, Einstein did not mention a "theory of relativity" that was combined with a theory of Lorentz (indeed, that is pure nonsense!). At cause is the translator's misreading of "prinzip" with "theorie". The same introduction is translated correctly in The collected papers of Albert Einstein, as follows:

    - Einstein 1907 according to Beck

    That is clear and makes perfect sense, although the double reference to Lorentz is potentially confusing. Thus it may be useful to keep in mind that he had earlier identified "the H. A. Lorentz theory" with Lorentz-1895 (also known as the Lorentz Electrodynamics Theory).
  5. Feb 8, 2012 #4
    I would more literally translate this as:
    So the only difference to Schwartz's translation is the word "principle" instead of "theory". But that's no big problem, since in the first sentence, Einstein evidently was alluding to Lorentz's 1895-theory, which actually violated the principle of relativity and thus also the theory of relativity. (Note that until ca. 1910, Einstein used the expression "principle of relativity" instead of "theory of relativity" in most of his publications, so Schwartz's translation makes perfect sense in historical perspective).
    In the next sentence, we have the first (and as far as I know) only occasion when Einstein directly referred to Lorentz's 1904 paper along with his own. Does this prove that he thinks that both papers describe the same theory? That's speculation - from the preceding we know, that both papers were dealing with the principle of relativity, not more.... And when we follow the rest of this article, we see that Einstein was elaborating on his own two-postulate approach, while Lorentz's method of introducing one auxiliary hypotheses after the other to hide the aether was not highlighted.:wink:

    So what did Einstein say about Lorentz's alleged "co-discovery" after 1907? There is an interesting interview in 1919, in which he said:
    However, Einstein wrote in a letter in 1954 that Lorentz was close, yet he didn't reach special relativity: (Letter to C.J.B. Bremer, July 15 1954):
    This reasoning for Lorentz's failure to completely arrive at special relativity is in good agreement with Lorentz's own understanding, as written by him in 1914 (except that Poincaré was mentioned, for sources see my earlier post https://www.physicsforums.com/showpost.php?p=3334553&postcount=41):
    Last edited: Feb 8, 2012
  6. Feb 8, 2012 #5
    Note also that apparently the label "the theory of relativity" had not yet emerged (that's another, minor deviation by Schwartz). And as you could have noticed from the earlier discussion, his mistranslation produces the twisted misunderstanding that there Einstein tries to combine a theory of Lorentz with the theory of relativity - while in reality he discusses the combination from which the new theory emerged. If you don't perceive the difference, let me put it in math: a+b=c is not the same as a+c=c.
    Good question, but perhaps a bit imprecise. He identifies his summary of those studies with the new theory.
    Ehm no. From the preceding we know that according to Einstein both papers of 1904-1905 were dealing with the unification of the principle of relativity and the Lorentz Electrodynamics theory. And it's easily verified that that is correct.
    Not surprisingly, knowing Einstein. :wink:
    That's not the topic here and I see no allegation of a "co-discovery" here... this thread is about the paper of 1907 - but thanks anyway. :smile:
    Note that people change their opinions over time, and that for example Lorentz demonstrated a shocking amnesia concerning Poincare at another occasion - but that's again another topic. :rolleyes:
    Last edited: Feb 8, 2012
  7. Feb 10, 2012 #6
    Wrap-up. As a reminder an extract from the 1907 paper:

    - Einstein 1907 according to Beck

    Also fine is the following on-the-spot translation by Histspec:

    And a little further we read:

    - Einstein 1907 according to Beck, with my abbreviation of footnotes in [].

    I think that there Einstein gave a fair description of how the works on relativity by Lorentz and Einstein were viewed at that time, and also how the second postulate relates to Lorentz's older 1895 theory.

    There remains a point that I have not yet checked, so I'll do that now here:

    Originally Posted by ghwellsjr
    Check: you refer to the last part of section 1, starting with the reference to MMX. But even according to Schwartz, Einstein doesn't refer at least seven times to Lorentz's 1904 theory.
    - I count there six references to Lorentz's electrodynamics theory of 1895, which was unsatisfying.
    - I also count one reference to Lorentz's paper of 1904, which he used together with his own paper of 1905 as basis for his following summary of the foundations of the new theory.

    Last edited: Feb 10, 2012
  8. Feb 10, 2012 #7


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    Here's the full quote, complete with links:
    And this issue started with my first post on the other thread where I said:
    And you responded with:
    You are maintaining that Einstein's theory of Special Relativity as presented in his 1905 paper is one and the same theory as the theory Lorentz presented in his 1904 paper and that Einstein pointed this out in his 1907 paper.

    I have been maintaining that they are two separate theories but share the same first postulate of the Principle of Relativity and this is borne out specifically and directly by Einstein in his 1907 paper as well as in all his other papers, books and speeches, although maybe not as directly or specifically.

    What makes them different theories is that they have a different second postulate which is the assignment of the one-way speed of light by Einstein to any rest state but to only one rest state by Lorentz.

    You have been objecting to the inclusion of the word "ether" when referring to Lorentz's theory when Einstein always talks about it when drawing a contrast between his theory and those that went before his.

    Einstein also talked in his 1907 paper about how Lorentz's theory evolved. Since he only refers to these as pre-MMX and post-MMX, I had no way of knowing the specific dates that would be applied to the different manifestations. But my point is that in all of them, Einstein called them theories, Einstein referred to them as incorporating ether, and they were all based on the principle of relativity.

    Now maybe the point you are making is that if we start with Lorentz's relativity theory, remove the assumption that light travels at c only in a fixed ether, add in Einstein's second postulate, and we will end up with Special Relativity, then I'm in complete agreement because that is what I have been saying all along.

    If that is not what you are saying, them please tell me how I have misunderstood what you are saying and what you would say instead.
  9. Feb 11, 2012 #8
    The issue here, which was spun off from the thread on alternative theories in order not to hijack it, is purely about what Einstein's 1907 paper states (sorry if the title doesn't make that clear; but I also mentioned that in the other thread). So, please don't try to mix the topic of that other thread into this thread. The other thread is still open. :smile:

    The discussion here should be useful to serve as reference for current as well as later discussions - our opinions about other papers or theories are off-topic.
    Note: as referenced by Einstein, the label "Lorentz's theory" there refers to Lorentz's electrodynamics theory of 1895. A translation of it together with the original text can found here:
    No. Lorentz's 1895 theory was incompatible with the relativity principle - even with the "fix" for MMX. You can verify that it wasn't based on it. Oops that is also slightly off-topic; but it may be helpful for correctly interpreting Einstein's 1907 paper. :tongue2:

    Last edited: Feb 11, 2012
  10. Feb 11, 2012 #9


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    Looking again at the unreliable translation, I see that there is a footnote when Einstein first mentions Lorentz's electrodynamic theory to the 1895 paper. But when Einstein says that it was incompatible with the Principle of Relativity, he was talking about the PoR based on the Galilean transformation, because Lorentz had not yet fully developed his transformation, correct?
  11. Feb 11, 2012 #10
    The relativity principle does not depend on transformations but instead, transformations can be developed in order to match the PoR. But indeed, the Lorentz transformation doesn't follow from that theory.
    And funny enough the translation that is unreliable at an important place is the more reliable one at another place, see my next post. :smile:
    Last edited: Feb 11, 2012
  12. Feb 11, 2012 #11
    There is a puzzling sentence in the introduction, as it suggests to me a double misunderstanding by Einstein in a single sentence, which is unlikely. Perhaps someone else can offer a more probable explanation.

    Funny enough, concerning this sentence my appreciation of translations is just the opposite of before: the translation by Beck is erroneous nonsense (about forces that are not states of a substance but things!) and instead I will cite the better translation by Schwartz :smile:

    - Einstein 1907 (Schwartz)

    Or, taking the best of both:
    - Einstein 1907 (Schwartz+Beck in the mix :smile: )

    My comments:

    - The conception of a material ether does not fit with the theory. However, I think that the concept "luminiferous ether" did not necessarily imply an ether that is made of some kind of matter, but perhaps I'm mistaken? :uhh:
    Alternatively one could propose that he meant the generic concept of a medium - but that is, as far as I can see, not warranted by the works on which he bases his discussion and he later disagreed with the idea that a medium would be incompatible with the theory. Thus, if that is what he meant, it was a blooper.

    - The word "only" appears to suggest that his description of electromagnetic fields is notably different from that of Lorentz-1895 to which he apparently referred. However, that description is not in contradiction with Lorentz's description in that paper:
    Thus, why did Einstein write "Only" instead of "Also"? Was that just a mistake or is there an incompatibility that I overlook?

    Last edited: Feb 11, 2012
  13. Feb 11, 2012 #12
    Try the following translation:


    Well, in 1909 Einstein was even more radical:

    So in both 1907 and 1909, Einstein thought that the relativity principle demands a medium-less or "empty space".

    The conceptual incompatibility is the state of motion of Lorentz's aether. If you look at his 1920 aether speech, Einstein wrote:
    * That the only mechanical property Lorentz left to the aether, was its "state of rest".
    * That the aether of general relativity emerges from Lorentz's aether by "relativization", that is, removing also the last mechanical property - its "state of rest".
    * But this aether may not be thought of as endowed with the quality characteristic of ponderable media, as consisting of parts which may be tracked through time. The idea of motion may not be applied to it.
    Thus the very "idea of motion" of the aether is completely banned in Einstein's theory (both special and general), but remains as a hidden entity in Lorentz's theory - this is what brings people to distinguish between "special relativity" and "Lorentz ether theory".

    Well, he always denied the generic concept of a "mechanical" medium having a "state of motion" - even in his both aether speeches. So as long as "the idea of motion" can be applied to the aether, so long it is "mechanical".

  14. Feb 11, 2012 #13
    Thanks, that is a pertinent point. It supports my impression that his claim was a philosophical opinion (which he rejected later) that did not directly follow from the papers on which he based his summary.

    I don't follow your explanation, as "matter" isn't identical to "mechanical" - except if it implies that Einstein had simply forgotten Lorentz's rejection of an ether made of matter. As formulated, it appears that he should have written "Also", not "Only".

    And was there another ether speech than the one of 1920?
    BTW, since you brought it up (but we are not going to discuss that paper in this thread), he explained what he meant with "applying the idea of motion" by comparing the ether to water of which its state of motion is fundamentally undetectable. Apparently he adhered to the "Machian" school of philosophy according to which we may not contemplate unmeasurable qualities. :bugeye:

    Anyway, thanks for the suggestions! :smile:
    Last edited: Feb 11, 2012
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