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Unformatted text preview: NO SUCCESS LIKE FAILURE . . . : EINSTEINS QUEST FOR GENERAL RELATIVITY, 19071920 MICHEL JANSSEN 1. Introduction In 1905, Einstein published what came to be known as the special theory of rela- tivity, extending the Galilean-Newtonian principle of relativity for uniform motion from mechanics to all branches of physics. 1 Two years later he was ready to extend the principle to arbitrary motion. He felt strongly that there can only be relative motion, as is evidenced, for instance, by his opening remarks in a series of lectures in Princeton in 1921, published in heavily revised form the following year (Einstein 1922c). A typescript based on a stenographers notes survives for the first two, non-technical lectures. On the first page of this presumably verbatim transcript we find Einstein belaboring the issue of the relativity of motion in a way he never would in writing: 2 Whenever we talk about the motion of a body, we always mean by the very concept of motion relative motion ...These conditions are really quite trivial ...we can only conceive of motion as relative motion; as far as the purely geometrical acceleration is concerned, it does not matter from the point of view of which body we talk about it. All this goes without saying and does not need any further discussion (CPAE 7, Appendix C, [p. 1]). Although Einstein insists that these points are trivial, we shall see that they are not even true. What makes his comments all the more remarkable is that by 1921 Einstein had already conceded, however grudgingly, that his general theory of relativity, worked out between 1907 and 1918, does not make all motion relative. In a paper entitled Is general relativity necessary for Einsteins theory of gravitation? published in one of the many volumes marking the centenary of Einsteins birth, the prominent relativist Sir Hermann Bondi (1979) wrote: It is rather late to change the name of Einsteins theory of gravitation, but general relativity is a physically meaningless phrase that can only be viewed as a historical memento of a curious philosophical observation (181). 3 Einstein obviously realized from the beginning that there is a difference between uniform and non-uniform motion. Think of a passenger sitting in a train in a railway station looking at the train next to hers. Suppose thatwith respect to the stationone train is moving while the other is at rest. If the motion is uniform 1 2 Michel Janssen and if the only thing our passenger sees as she looks out the window is the other train, there is no way for her to tell which one is which. This changes the moment the motion is non-uniform. Our passenger can now use, say, the cup of coffee in her hand to tell which train is moving: If nothing happens to coffee, the other one is; if the coffee spills, hers is....
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This note was uploaded on 12/30/2011 for the course PHYSCS 675 taught by Professor Jacobson during the Fall '08 term at Maryland.
- Fall '08