What newly released papers reveal about Einstein





On July 22 the Einstein Papers Project, located at the California Institute of Technology in Pasadena, will release the 12th volume of letters written or received by Albert Einstein—791 of them—plus transcripts of several notable lectures and interviews the physicist gave, covering the year 1921. It was a momentous 12 months. You might think there are no new revelations to be made about him, but for Einstein groupies the current volume addresses at least one key question: what did Einstein know about an 1887 experiment that discovered that the speed of light is invariant, regardless of the observer's speed or direction of motion—an idea that forms the core of special relativity and that Einstein did not mention when he laid out the theory of special relativity in a 1905 paper?

Called the Michelson-Morley experiment, it disproved the existence of the ether, a substance once thought to carry light waves and form an absolute reference frame for space. ...

The new volume of Einstein papers includes a previously unknown transcript of an address Einstein delivered at the Parker School in Chicago on May 4, 1921. There, he made what Caltech science historian Diana Buchwald, director of the Einstein Papers Project, calls "a most intriguing remark." "On this occasion," she writes in her introduction to the new volume, "and perhaps to please the local audience [the Michelson-Morley experiment was done in nearby Cleveland], Einstein stated that, already as a student, he had come across the Michelson-Morley experiment: 'But when I was a student I saw that experiments of this kind had already been done, in particular by your compatriot, Michelson.'" She notes that the role played by the experiment "in the development of Einstein's thinking on relativity has long been the subject of scholarly debate. Some researchers have even entertained the possibility that in 1905 Einstein had been unaware of the experiment, to which there is no reference in his celebrated paper." The new evidence from his 1921 lecture shows once and for all that he was indeed aware of the Michelson-Morley work.

There is no insinuaton of plagiarism, or even of failure to credit an influential earlier discovery. Instead, the question of what Einstein knew about the speed of light, and when he knew it, has long intrigued historians. For as [Einstein biographer Walter] Isaacson so astutely pointed out, physicists before Einstein questioned the idea of absolute motion, absolute space, and absolute time. Yet it was Einstein who took the ultimate leap, forging that insight into special relativity. In light of the newly discovered transcript, it seems safe to add the invariant speed of light to the list that many physicists knew about, but which only Einstein was able to forge into special relativity.



comments powered by Disqus
History News Network