Why Einstein First Visited Caltech

by Andrew Moseman

Diana K. Buchwald, Caltech’s Robert M. Abbey Professor of History and director and general editor of The Einstein Papers Project, delivered a Watson Lecture during the 2023–24 season detailing Albert Einstein’s early connections to Caltech. She shared insights into Einstein's scientific work and private life in the late 1920s and early 1930s, when Einstein visited Caltech to spend three consecutive winters in the California sunshine. Buchwald analyzed and vividly illustrated Einstein’s scientific motivations for making the trip—and his newfound enjoyment of Pasadena’s Rose Parade, Hollywood, and friendly strangers among the numerous events he attended.

“[Einstein] was one of the earliest champions of international reconciliation among former enemy nations—and that's how his first invitation to Caltech came about,” Buchwald said in her lecture. Einstein had been collaborating with Caltech President Robert A.  Millikan and Marie Curie at the League of Nations when the first invitation to Caltech came about in the mid-1920s. But later, Einstein suffered health complications that prevented him from traveling.

He recovered sufficiently by his 50th birthday in March 1929. “The hullabaloo preceding that day caused him to flee the journalists and the postman because he received hundreds of letters and telegrams,” Buchwald said. “He got mountains of congratulations, which we, at the Einstein Papers Project, duly published, mostly in an abstract, in our Volume 16 in 2021.” But Einstein also received a sailboat from three banker friends, which was built over the next few months. Sailing and music were Einstein's only hobbies and his sole relaxation. He loved sailing, and therefore it wasn't a surprise that he came by boat to Caltech.”

Einstein discussed new scientific discoveries, theories, experiments, and instruments with colleagues at Caltech, Buchwald explained, including mathematician Walther Mayer, who accompanied him on a luxury cruise. Einstein also owed a debt of gratitude to several Caltech scientists.

“In the 1920s, the physicist Dayton Miller published numerous papers purporting to have experimental data showing that he consistently observed an ‘ether drift' of some kind with his interferometer, both on Mount Wilson and in the basement of the laboratories at Case Western University in Cleveland,” Buchwald said. “If correct, the existence of such a relative motion between Earth and the purported medium of an ether would disprove the theory of relativity.”

Einstein never engaged publicly with Miller's claims, but Millikan and his colleagues at Caltech were able to test them. They built a new instrument that was four to five times more sensitive than Miller's. And, by 1926, they were able to prove that the repetition of the famous Michelson-Morley experiment—Miller's experiment—led to a negative result. This development emboldened Einstein. Caltech astronomers were thereby also showing that progress was being made toward proving the correctness of general relativity, specifically, for its predictive power beyond the Newtonian gravitational theory.

Shortly before Einstein’s visit, Edwin Hubble had demonstrated that fainter galaxies were, the farther they were from us and the farther they were moving from us. While this discovery led to the modern conception of general relativity, it ran counter to Einstein’s first cosmological interpretations of general relativity in 1916–18 when galaxies had not yet been discovered, and when he worked on the assumption of a static universe.

“For Einstein, [coming to Caltech] was a unique opportunity to be together with these colleagues with whom he had corresponded quite intensely, over many years,” Buchwald said. “So, he embarked on a luxurious steamship in December 1930. The voyage lasted almost a month with a brief stopover in New York and then through the Panama Canal to Long Beach harbor. He worked during most of his trip. It is said that stewards carried away basketfuls of scratch paper that he was throwing away.”

Watch the rest of Buchwald’s lecture to hear about Einstein’s stay in Pasadena, his impressions of Caltech and Pasadena, and much more.