Hendrik Antoon Lorentz, the ether, and the general theory of relativity

Abstract

From the early days of the development of the general theory of relativity the Dutch physicist Hendrik Antoon Lorentz showed a lively and active interest in this theory of gravitation. He devoted much time and energy to understanding the theory and made several important contributions himself. In this paper I will discuss Lorentz's work in the field of general relativity; in addition I will address the question of the apparent discrepancy between Lorentz's enthusiasm for the general theory of relativity and his belief in the existence of an ether. It is well known that until his death in 1928 Lorentz kept insisting on the usefulness of an ether. In spite of his often-expressed admiration for Einstein's special theory of relativity, he preferred his own ether-based 'theory of electrons'. Lorentz admitted that his theory and the special theory of relativity had the same empirical consequences and that the ether could not be experimentally detected, but he maintained that some kind of ether was needed as carrier of the electromagnetic field. As he said in his Theory of Electrons: "I cannot but regard the ether, which can be the seat of an electromagnetic field with its energy and its vibrations, as endowed with a certain degree of substantiality, however different it may be from all ordinary matter."1 In the light of this and many similar statements it seems remarkable that Lorentz occupied himself with the general theory of relativity, in which the ether played no role whatsoever. I will show that, in fact, Lorentz's point of view was not inconsistent, and that he had the same objections against the general theory as against the special theory.