Gravitation in the Twilight of Classical Physics: An Introduction

More than is the case for any other theory of modern physics, general relativity is usually seen as the work of one man, Albert Einstein. In taking this point of view, however, one tends to overlook the fact that gravitation has been the subject of controversial discussion since the time of Newton. That Newton’s theory of gravitation assumes action at a distance, i.e., action without an intervening mechanism or medium, was perceived from its earliest days as being problematical. Around the turn of the last century, in the twilight of classical physics, the problems of Newtonian gravitation theory had become more acute. Consequently, there was a proliferation of alternative theories of gravitation which were quickly forgotten after the triumph of general relativity. In order to understand this triumph, it is necessary to compare general relativity to its contemporary competitors. As we shall see, general relativity owes much to this competition. A historical analysis of the struggle between alternative theories of gravitation and the different approaches to the problem of gravitation thus complements the analysis of Einstein’s efforts. An account of the genesis of general relativity that does not discuss these competitors remains incomplete and biased. At the same time, this wider perspective on the emergence of general relativity provides an exemplary case of alternatives in the history of science, presenting a whole array of alternative theories of gravitation and the eventual emergence of a clear winner. It is thus an ideal topic for addressing long-standing questions in the philosophy of science on the basis of detailed historical evidence.