Einstein Papers Project’s newest volume: Einstein wrestles with politics and physics, 1929–1930 By Cynthia Eller

The Collected Papers of Albert Einstein provides a rare opportunity for readers to move through Einstein’s life at a leisurely pace, perusing all his writings, from his informal correspondence to his most carefully argued scientific theories. Volume 17, which covers the period from June 1929 to November 1930, was published by Princeton University Press on September 3, 2024.

Since 1987 the Einstein Papers Project, based at Caltech, has been releasing a volume of Einstein’s correspondence and papers approximately every three years. Each volume documents, translates, and in many cases recovers previously lost writings, acting as a snapshot not only of Einstein’s life at the time, but of all the scientific and political discussions swirling around him. This context makes the series a rich resource for anyone interested in the culture and thought of the era.

Volume 17 finds Einstein living mainly in Berlin, though traveling throughout Europe to attend conferences and receive honorary degrees. The volume closes just before Einstein ventures to the United States in December of 1930 for the first of the three winter terms he would spend at Caltech as a visiting scientist before permanently leaving Europe and taking a position at the Institute for Advanced Study in Princeton, New Jersey.

Though Einstein could not have known it at the time, says Diana Kormos-Buchwald, Caltech’s Robert M. Abbey Professor of History and director and general editor of the Einstein Papers Project, this was “a watershed event for him, a time when he yet again seriously considered either leaving academia altogether—as he had done in the 1920s during vicious attacks in Germany against his person and his theory of relativity—or emigrating, as he would eventually do in 1933.”

“During the 18 months covered by this volume,” Kormos-Buchwald adds, “Einstein’s output didn’t flag, and his correspondence continued to increase, with an average of more than 90 incoming and outgoing letters and writings each month.” Einstein was also busy with administrative and academic obligations, some of which involved travel, such as attending sessions of the International Committee of Intellectual Cooperation in Geneva and the Sixth Solvay Conference in Brussels. He continued his passionate work promoting pacifism and speaking out on behalf of Europe’s Jewish population. Amidst all this, Einstein acquired a sailboat in early June 1929 and continued to listen to and perform music.

Volume 17 includes nine published scientific papers as well as unpublished papers and calculations Einstein developed in search of a unified field theory. “One nice discovery,” Kormos-Buchwald says, “was a notebook containing ideas and elaborations of the teleparallel theory, documenting many doubts and false starts. But that helped us put together various fragments and drafts of a paper he intended to publish.”

Einstein was using an specialized form of geometry, telleparallelism, to try to bring together electromagnetism and gravitation in a single unified field theory. After correspondence with French mathematician Élie Cartan, who had previously worked on teleparallel theory, Einstein withdrew his own manuscript from publication in order to revise it. “Eventually Einstein’s ‘Unified Field Theory Based on a Riemannian Metric and Distant Parallelism’ became his most comprehensive and self-contained exposition on the teleparallel approach, which he later abandoned,” Kormos-Buchwald explains.

Ze’ev Rosenkranz, who worked on volume 17 as a senior editor with the Einstein Papers Project, says that the most challenging documents in the volume were related to Einstein’s pacifist activism after the outbreak of violence in British-ruled Palestine in 1929. “These documents were formidable to annotate due to the fact that the eruption of intercommunal violence between Palestinian Arabs and Jews in that period was unfortunately only a portent of the decades of intense bloodshed that has occurred in the region hence and is still ongoing,” Rosenkranz says.

“Einstein also continued to persevere in one of his earliest political involvements: his efforts to promote peace and international cooperation that had started a decade earlier,” Kormos-Buchwald notes. “He encouraged disarmament, conscientious objection, and apolitical pacifism. These were to be topics he would actively pursue on his trip to Caltech.” Only a few years later, Einstein abandoned unconditional pacifism, regarding Germany’s threat to the world as too great.

When asked which volume of the Collected Works is her favorite, Kormos-Buchwald replies, “My favorite volume is always the latest one, with a great sigh of relief and pride that the editors have traversed another segment of Einstein’s turbulent life and career.”

When completed, the Collected Works will comprise nearly 30 volumes and will contain more than 14,000 documents. The Einstein Papers Project is supported by Caltech, the Hebrew University of Jerusalem, and Princeton University Press.