The Origins of the FitzGerald Contraction

Abstract

The FitzGerald–Lorentz contraction hypothesis has become well known in connection with Einstein's theory of relativity, and its role in the origin of that theory has been the subject of considerable study. But the origins of the contraction idea itself, and particularly of G. F. FitzGerald's first statement of it in 1889, have attracted much less attention and are surrounded by several misconceptions. The hypothesis has usually been depicted as a rather wild idea put forward without any real theoretical justification simply to explain away the troublesome null result of Michelson and Morley's 1887 ether drift experiment. In the words of Gerald Holton, ‘it has traditionally been called the very paradigm of an ad hoc hypothesis’. H. A. Lorentz, who hit upon the contraction idea independently in 1892, has been credited with giving it some justification in terms of his electron theory, but little or none of this credit has been extended to FitzGerald. His statement of the contraction hypothesis has usually been viewed, in the words of his friend R. T. Glazebrook, as nothing more than ‘the brilliant baseless guess of an Irish genius’.