Il6 RELATIVITY, THE SPECIAL THEORYfor the first and last time: 'I have come among men who for many years have been
true comrades with me in my labors. You, my honored Dr Michelson, began with
this work when I was only a little youngster, hardly three feet high. It was you
who led the physicists into new paths, and through your marvelous experimental
work paved the way for the development of the theory of relativity. You uncovered
an insidious defect in the ether theory of light, as it then existed, and stimulated
the ideas of H. A. Lorentz and FitzGerald out of which the special theory of
relativity developed' [E10]. One would think that Einstein might have associated
himself explicitly with Lorentz and FitzGerald had he believed that the occasion
warranted it. He was worldly enough to know that this would be considered an
additional compliment to Michelson rather than a lack of modesty.
Michelson was very ill at the time of that festive dinner and died four months
later. On July 17, 1931, Einstein, back in Berlin, gave a speech in Michelson's
memory before the Physikalische Gesellschaft of Berlin [Ell]. The talk ended
with a fine anecdote. In Pasadena, Einstein had asked Michelson why he had
spent so much effort on high-precision measurements of the light velocity.
Michelson had replied, 'Weil es mir Spass macht,' Because I think it is fun. Ein-
stein's main remark about the Michelson-Morley experiment was, 'Its negative
outcome has much increased the faith in the validity of the general theory of rel-
ativity.' Even on this most natural of occasions, one does not find an acknowl-
edgement of a direct influence of Michelson's work on his own development.
Nevertheless, the answers to both questions—did Einstein know of Michelson's
work before 1905? did it influence his creation of the special theory of
relativity?—are, yes, unquestionably. We know this from discussions between
Shankland and Einstein in the 1950s and from an address entitled 'How I Created
the Relativity Theory' given by Einstein on December 14, 1922, at Kyoto Uni-
versity (and referred to in what follows as the Kyoto address). Let us first note
two statements made by Einstein to Shankland, recorded by Shankland soon after
they were made, and published by him some time later [S6], as well as part of a
letter which Einstein wrote to Shankland [S7].*
a) Discussion on February 4, 1950. 'When I asked him how he had learned of
the Michelson-Morley experiment, he told me that he had become aware of it
through the writings of H. A. Lorentz, but only after 1905 [S. 's italics] had it
come to his attention! "Otherwise," he said, "I would have mentioned it in my
paper." He continued to say that experimental results which had influenced him
most were the observations on stellar aberration and Fizeau's measurements on
the speed of light in moving water. "They were enough," he said' [S6].
b) Discussion on October 24, 1952. 'I asked Professor Einstein when he had
first heard of Michelson and his experiment. He replied, "This is not so easy, I
"This letter, written at Shankland's request, was read before the Cleveland Physics Society on the
occasion of the centenary of Michelson's birth.