PASADENA, Calif.-In the latter half of 1920, Albert Einstein faced a series of increasingly acrimonious public attacks against his recently confirmed theory of general relativity. He considered leaving Berlin, which would have deprived Germany of its most famous scientist. Colleagues, friends, and unknown admirers offered support, while Einstein worried about the care of his two sons and ex-wife in Switzerland, and his new family in Berlin.
This is the historic context of the tenth volume of The Collected Papers of Albert Einstein, which is being released this week by Princeton University Press under the editorship of the Einstein Papers Project at the California Institute of Technology.
Volume 10 contains Einstein's correspondence from May to December 1920, as well as a substantial number of previously unavailable letters from 1909 to 1920, most of them written by Einstein. These originate from the bequest of family correspondence deposited at the Albert Einstein Archives at the Hebrew University in Jerusalem by his stepdaughter Margot Einstein, who stipulated that they remain closed for twenty years after her death.
The volume presents letters written by Einstein's young sons Hans Albert and Eduard Einstein in which they report on their hobbies and reading and express their longing for the absent father. It also includes for the first time since Volume 1 a number of letters written by his wife, Mileva Einstein-Maric. The largest group of supplementary letters, written by Einstein between April 1916 and October 1919, mainly in the form of postcards and resembling a travel diary, is addressed to Elsa Einstein, his cousin and future second wife.
It also contains new information on Einstein's personal life during the last eight months of 1920, such as his first vacation with his sons in Southern Germany and his renewed attempts to move his Zurich family there. We also gain a glimpse into the unique perspective of Elsa Einstein, in the few extant letters, of her relationship to Einstein.
In addition, in letters newly available at the Central Library in Zurich addressed to his friend Heinrich Zangger, Einstein confides on personal matters, worries, and family crises, his negotiations with Mileva Einstein-Maric, his feelings about his sons, the separation, divorce, and contemplated second marriage. The war, his opposition to it, and his sense of alienation from some of his academic colleagues in Berlin come to the fore, as do the difficulties of crossing international borders, the widespread hunger, and economic hardships.
The second half of Volume 10 finds Einstein full of optimism about Germany's new democracy. He vigorously promotes general relativity and the endeavors of other scientists toward its further confirmation. We see Einstein firmly positioned as a central figure in the lively cultural atmosphere of the young Weimar Republic, as witnessed by correspondence with renowned German philosophers of the time, such as Ernst Cassirer, Hans Reichenbach, and Max Wertheimer.
Scientific issues are discussed in the correspondence as well, shedding light on his associations with fellow physicists in Europe and the United States, and his lectures on the special and general theories of relativity within Germany and during his trips to Holland, Denmark, and Norway. The documents present the challenges Einstein faced as a result of his recently acquired celebrity status, his subsequent entrance into the public arena, and the contentious public attacks against relativity.
The intensity of this period, during which anti-Semitism and nationalistic sentiment seeped into scientific debate, is reflected in numerous letters. The successful completion of the intricate process of Einstein's appointment as Special Professor at the University of Leyden leads to his well-known inaugural lecture on "Ether and Relativity" in October 1920. The letters document in detail his sojourns in the Netherlands, the hospitality of many Dutch colleagues, his involvement with issues at the forefront of physics, and especially his significant intellectual and personal bonds with Paul Ehrenfest. He visits Oslo and Copenhagen, where he meets with Niels Bohr, and receives invitations to America.
The Collected Papers of Albert Einstein, a collaborative project with participants from several countries, are edited by Diana Kormos-Buchwald, a professor of history at Caltech; Tilman Sauer, a senior research associate in history; Ze'ev Rosenkranz, Jozsef Illy, and Virginia Iris Holmes, members of the research staff in the Einstein Papers Project; and by associate editors Jeroen van Dongen, Daniel Kennefick, and A.J. Kox.