This reprints an essay written ca. 1983, «‘What Song the Syrens Sang’: How Did Einstein Discover Special Relativity?» in John Stachel, Einstein from «B» to «Z».

If you have read Edgar Allen Poe’s «The Murders in the Rue Morgue,» perhaps you remember the epigraph
that Poe chose for this pioneer detective story: What song the Syrens sang, or what name Achilles assumed when he hid himself amongwomen, though puzzling questions, are not beyond all conjecture.1 I believe that the problem of how Einstein discovered the special theory of relativity (SRT) falls into this category of «puzzling questions,» that «are not beyond all conjecture.»2 Let me begin by explaining why. When I started work on the Einstein Papers, there was already a large literature on the origins of SRT compared, say, tothe rather scanty amount published on the origins of the general theory of relativity (GRT). So I assumed that the development of SRT must be fairly clear. However, I soon learned that the amount of work published on the origin of SRT and GRT are just about inversely proportional to the available primary source material. For GRT, we have a series of Einstein’s papers from 1907 to 1915, capturingthe successive steps of his search for the final version of the theory. In addition, there is extensive contemporary correspondence on the subject, several research notebooks, records of lectures given by Einstein during this period, not to mention a number of later reminiscences and historical remarks by Einstein.3 For SRT we have the paper On the Electrodynamics of Moving Bodies, in which thetheory was first set forth in 1905 in its finished form, indeed a rather polished form (which is not to say that it bears no traces of its gestation process). The only earlier documentary evidence consists of literally a couple of sentences to be found in the handful of preserved early Einstein letters (I will quote both sentences later). We do have a number of later historical remarks by Einsteinhimself, sometimes transmitted by others (Wertheimer, ReiserKayser, Shankland, Ishiwara, for example), which raise many problems of authenticity and accuracy; and some very late Einstein letters, answering questions such as whether he had prior knowledge of the Michelson-Morley experiment, what works by Lorentz he had read, the influence of Poincaré, Mach, Hume, etc., on his ideas; Einstein’sreplies are not always self-consistent, it must be noted.4 Yet the urge to provide an answer to the question of the discovery of SRT has proven irresistible to many scholars. It is not hard to see why: A twenty-six year old patent expert (third class), largely self-taught in physics, who had never seen a theoretical physicist (as he later put it), let alone worked with one, author of several competentbut not particularly distinguished papers, Einstein produced four extraordinary works in the year 1905, only one of which (not the relativity paper) seemed obviously related to his earlier papers. These works exerted the most profound influence on the development of physics in the 20th Century. How did Einstein do it? Small wonder that Tetu Hirosige, Gerald Holton, Arthur I. Miller, Abraham Pais,John Earman, Clark Glymour, Stanley Goldberg, Robert Rynasiewicz, Roberto Torretti, et al., have been moved to study this question. I shall not try to record my debts to and differences with each of these scholars, lest this survey become even longer and more tedious than it is already; but must at least acknowledge the influence of their work on my own.5 I resisted the urge to conjecture for someyears, but have finally succumbed, so I can well understand the temptation.

Contrary to my original, naive expectation, no general consensus has emerged from all this work. Given

the nature of the available documentation and the difficulty of understanding any creative process-let alone that of a genius-this really is not surprising. I now believe that the most one can hope to do in…