The Genesis of General Relativity

Abstract

The relationship between Einstein and Mach is often discussed as a prototypical case of the influence of philosophy on physics.1 It is, on the other hand, notoriously difficult to accurately pinpoint such influences of philosophy on science, in particular with regard to modern physics. To a working scientist, such influences must seem to belong to a past era. There seems to be little room left for philosophy in the practice of today’s physics. It plays virtually no part in the physics curriculum, and scholars who are both active physicists and philosophers are rare exceptions. In view of this situation it may be appropriate to reexamine the mythical role that philosophy played for one of the founding heroes of modern physics, Albert Einstein. It is conceivable that the disjointed remarks on philosophy that are dispersed throughout his oeuvre can be integrated into a coherent image of what may then rightly be called his philosophy. But even if such a reconstruction should be successful and yield more than an eclectic collection of occasional reflections, the more decisive question of the utility of philosophy for his science would be left unanswered. In fact, Einstein as a philosopher may have been a rather different persona from Einstein the physicist, and having two souls in one breast would not be an atypical state of affairs for a German intellectual. This contribution will therefore not undertake a systematic attempt at reconstructing his philosophy, but rather be limited to a case study of the interaction between philosophy and physics, reexamining the impact of Mach’s philosophical critique of classical mechanics on Einstein’s discovery of general relativity.2 This reexamination is made possible by newly discovered documentary evidence concerning Einstein’s research as well as by the achievements of recent studies in the history of general relativity.3 Both factors contribute to an historical understanding of the relation between Mach’s philosophy and Einstein’s physics that is not only richer in detail, but also in context, and hence able to reveal the alternatives available to the historical actors in the search for a new theory of gravitation.