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Michel Janssen

Reconsidering a Scientific Revolution: the Case of Lorentz versus Einstein
Michel Janssen, Physics in Perspective 4 (2002): 421–446.

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The relation between Einstein's special theory of relativity and Lorentz's ether theory is best understood in terms of competing interpretations of Lorentz invariance. In the 1890s Lorentz proved and exploited the Lorentz invariance of Maxwell's equations, the laws governing electromagnetic fields in the ether, with what he called the theorem of corresponding states. To account for the negative results of attempts to detect the earth's motion through the ether, Lorentz, in effect, had to assume that the laws governing the matter interacting with the fields are Lorentz invariant as well. This additional assumption can be seen as a generalization of the well-known contraction hypothesis. In Lorentz's theory, it remained an unexplained coincidence that both the laws governing fields and the laws governing matter should be Lorentz invariant. In special relativity, by contrast, the Lorentz invariance of all physical laws directly reflects the Minkowski space-time structure posited by the theory. One can thus produce a common cause argument to show that the relativistic interpretation of Lorentz invariance is preferable to Lorentz's interpretation.