But Polanyi devotes only a few pages to these matters, for his main proof depends on what he calls “the story of Relativity.” That theory was indeed taken by the positivists to show that through instrumentalist thinking Einstein had freed l9th-century physics from its metaphysical underpinnings, and thereby made the breakthrough to modern science. Polanyi correctly points out that every textbook of physics tried to present the rise of relativity as the necessary response to an experimental situation, namely the supposed null result of the Michelson-Morley experiment searching for an ether drift in l887 -- fully in accord with the sensationist or positivist view of how theories must proceed. (As well, we should add, the easiest pedagogic method of convincing students that they must take seriously what otherwise would be so counter-intuitive.) But, Polanyi declares, “the historical facts are different.”54 He noted that Einstein, in his publication, had not mentioned the Michelson-Morley experiment at all, and concludes from it that this theory was proposed “on the basis of pure speculation, rationally intuited by Einstein before he had ever heard about it.”55No, the facts are not different. The textbooks are correct that the rise of relativity was indeed the necessary response to an experimental situation. See my book for details.
Nevertheless, Polanyi eventually convinced other philosophers and Einstein historians that Einstein invented special relativity with pure thought, while ignoring experiments like Michelson-Morley.
This is crazy. Relativity pioneers FitzGerald, Lorentz, Poincare, and Minkowski all said that the Michelson-Morley experiment was crudial to their work. Einstein himself said in 1909 essay that the experiment was crucial:
The Michelson and Morley interference experiment showed that, in a special case, second-order terms also cannot be detected, although they were expected from the standpoint of the ether-at-rest theory. To include this experiment in the theory, Lorentz and FitzGerald introduced the postulate that all objects, including the parts of Michelson and Morley's experimental set-up, changed their form in a certain way, if they moved relative to the ether. ...Einstein did later acknowledge that the experiment had little or no direct influence on his famous 1905 paper. That is plain to see from reading the paper. Einstein gave an exposition of Lorentz's theory, without giving Lorentz's reasoning. As Lorentz later said, Einstein postulated what had previously been proved from experiment an analysis.
Michelson's experiment suggests the axiom that all phenomena obey the same laws relative to the Earth's reference frame or, more generally, relative to any reference frame in unaccelerated motion. For brevity, let us call this postulate the relativity principle.
I draw attention to the history of relativity because it is so frequently used to sell some completely wrong picture of what science is all about.
A comment on my FQXi essay argues that Michelson-Morley was not crucial because it is consistent with emission (particle) theories of light. But there was a lot of evidence at the time that light was an electromagnetic wave, and so the emission theories were not popular. It is a historical fact that Michelson-Morley was crucial to relativity.
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