EPP Editors' Reflections on CPAE Vol. 17: Daniel Kennefick
Documentary editing is a meticulous process. Thorough research and skillful attention to detail are expected standards among practitioners in the field. One thing people outside of the field may not consider is that editors work to avoid injecting their present day understanding of historical events into their annotation of documents. Separating one's knowledge of events as they later unfolded from factual details of the historical record requires rigor and balance. Editorial work and editorializing are distinct and separate things. Einstein Papers Projects editors engage in the former, working to contextualize facts without the interference of hindsight. Project historians and researchers spend years sorting, analyzing and researching the materials that go into our volumes. Understanding this makes it especially interesting to find out what our editors think of the documents they edit, beyond the confines of the documentary editing process. Here, EPP Science Editor, Daniel Kennefick writes about a letter Einstein wrote to astronomer August Kopff in January of 1930. Kennefick's summary of the letter includes his reflection on Einstein's scientific outreach. The letter will appear as Document 206 in the forthcoming Collected Papers of Albert Einstein, Volume 17.
The Polish Boy and the Moon
Letter to August Kopff, 13 January 1930
Einstein tells Kopff, an Astronomer at the University of Berlin, about a letter from a boy in Poznan in Poland who asks if the Moon will one day fall to Earth. Although we do not have the correspondence between Einstein and the boy, it is clear that Einstein was determined to get his reply right, because he wrote to a professional astronomer for confirmation. He presumes that the boy has heard about the phenomenon of tidal friction and imagined that this must lead to a damping of the Moon's motion, which would appear to be consistent with the Moon slowly inspiraling towards the Earth until an eventual and inevitable collision. In fact, conservation of angular momentum demands that tidal friction transfers angular momentum from the Earth's rotation to the Moon's orbital motion, with the result that the Moon draws further away from us, not closer. Although Einstein is unfamiliar with the literature on the subject, Kopff confirms that his intuition is correct, referring him to the work of Poincaré. In the ensuing correspondence they discuss ideas about the formation of the solar system based upon tidal friction as part of a process which moves planets farther away from the Sun. In this correspondence we see Einstein's typical commitment to scientific outreach and his wide-ranging interest in all matters related to physics. Not only does Einstein experience an endless fascination with the physical world and its behavior but he wishes to share his interest with everyone who shares his interest if not his insight.