Monday, March 12, 2012

New spacetime conception in 1905

Mario Bacelar Valente just posted Did the concepts of space and time change that much with the 1905 theory of relativity?, saying:
The advent of the 1905 theory of relativity is rightly considered as a breakthrough moment in the history of physics; in particular. it is widely accepted that it brought a new conception of space and time. The purpose of this work is to reevaluate to what point and in what sense can we consider that the conception of space and time went through a transformation when going from Newtonian mechanics to the theory of relativity.
It is widely accepted that the new conception of space and time became popular from Minkowski's 1908 paper. As explained in How Einstein Ruined Physics, Minkowski got his ideas from Poincare's 1905 paper, not Einstein's.

Valente relegates Lorentz and Poincare to a footnote:
53 Let us not forget that to Lorentz the so-called local time was just a mathematical artifact to help in calculations (see, e.g. Lorentz 1916, 57-8 and 187-9; Darrigol 2006, 11). Poincaré did notice that the local time had operational meaning since actually this is the time measured by an observer in absolute motion in relation to the ether; However Poincaré still considered a sort of absolute time (‘le temps réel’), the time measured by an observer in absolute rest in relation to the ether (see, e.g., Poincaré 1913, 43-6; Darrigol 2006, 17-9). It was Einstein who for the first time presented a truly relativistic notion of time in which physical time has to be defined and ‘spread’ within an inertial reference frame, and there is no preferred reference frame (see, e.g., Einstein 1905; Paty 1993, 148-52).
Like other modern historians, Valente is criticizing Lorentz and Poincare for their terminology in later years. The criticism is silly and misinformed. And it proves nothing, because even if they did use inferior terminology in 1913 and 1916, it would not have anything to do with who had the new space-time theory in 1905.

Valente credits Einstein for abolishing the aether (ether):
In 1905, in his criticism of Lorentz's electron theory Einstein, like others (see, e.g., Darrigol 2000, 366-72), defended the view that we must “give up [on] the ether” (Einstein 1910, 124). Einstein argument is based on the idea that the ether seems to enable a special reference frame in relation to which things might still be said to be in 'absolute' rest or motion. Since it turns out that it is not possible to determine experimentally the velocity of material things in relation to the ether, there is no way to distinguish the ether's reference frame from other inertial reference frames. Accordingly, Einstein considers that one should “give up the notion of a medium filling all of space” (Einstein 1910, 124). ... Later, within his theory of gravitation, Einstein put forward the idea that the curved space-time is a sort of ether (Einstein 1920).
Note that Valente is crediting Einstein for what he said about the aether in 1910, in spite of what he said in 1905 and 1920. Einstein did not criticize Lorentz's theory in 1905, and in succeeding years, Einstein and others called it the Lorentz-Einstein theory.

The answer to Valente's question is the Lorentz changed our conception of space and time in 1895, and Poincare changed it again in 1905. Einstein's 1905 paper was mostly an explanation of Lorentz's theory, and did not have any significant new conceptions.


  1. You say, "Einstein's 1905 paper was mostly an explanation of Lorentz's theory, and did not have any significant new conceptions." I think the Wikipedia article on History of Relativity gives a good account. Lorentz and others started postulating distortive effects of motion to "save apperarances". Einstein was the first to go "all in" and give up the Newtownian notion of absolute space. One might say this is just the official line, but yet his paper did cause a sensation. It must have set off some kind of flash in the collective physics mind.

  2. Actually, Einstein's 1905 relativity paper did not cause much of a sensation at the time. Lorentz's reasons for postulating distortive effects of motion were pretty much the same as Einstein's, and physicists in 1905 considered Einstein's paper to be just an elaboration of Lorentz's theory. Go ahead and look at Einstein's paper, and tell me where he went "all in" or where he distinguished himself from Lorentz.

    1. He goes "all in" in the introduction, where he cites the postulate of relativity and the constancy of "c" as a sufficient basis for dynamics. There's quite a bit about this in various Wiki articles, including one devoted to priority controversies. Reminds me of the prisoners who would tell jokes by calling out a number ... no need for me to spell everything out!

  3. Those introductory paragraphs have phrases like "it is known" and "as has already been shown", and recite the Lorentz theory. Nowhere does Einstein express any disagreement with what Lorentz had published. The relativity principle is nearly identical to what Lorentz and Poincare wrote years earlier.

    By comparison, papers by Lorentz, Poincare, and Minkowski are much bolder and do go "all in" with ideas that go against previous wisdom.