EINSTEIN, Albert (1879-1955). Two autograph letters signed (“A. Einstein” and ''A. Einstein'') to Paul Epstein, [Kiel,] 14 August 1921, one being a cover letter for the other.

EINSTEIN, Albert (1879-1955). Two autograph letters signed (“A. Einstein” and "A. Einstein") to Paul Epstein, [Kiel,] 14 August 1921, one being a cover letter for the other.

In German. Two pages and one page respectively, 280 x 191mm, in pencil.

Recommending the young Jewish physicist Paul Epstein for a post at Caltech: “Prof. Dr. Epstein is certainly one of the most prominent among the living theoretical physicists of the German-speaking world…”. Epstein had previously come to Einstein’s attention for his work on quantum theory, and Einstein had written a paper “On the Quantum Theorem of Sommerfeld and Epstein” in response. Einstein also refers to Epstein’s related work on the Stark Effect, which provided critical support to the then relatively new “Rutherford-Bohr atomic theory”, setting forth the model of the atom as we know it today.

Epstein was accepted for the professorship at Caltech in 1921; Einstein would join him there as a visiting professor for the winter terms of 1931-1933. Einstein had perceived early on that Epstein might have a better chance finding a position in America than in inter-war Europe; there is some suggestion in his correspondence that as a foreign-born Jew, Epstein had been denied a job at Frankfurt in 1920.

Pre-Lot Text
PROPERTY FROM THE DESCENDANTS OF PAUL S. EPSTEIN (1883-1966)
Paul S. Epstein (1883-1966), the first European-trained physicist to teach at the California Institute of Technology, was born in Warsaw and educated in Moscow. Foreseeing the coming of the Russian Revolution he moved to Munich to work with Arnold Sommerfeld on the theory of electromagnetic waves and received his Ph.D. in 1914. At the outbreak of the First World War, Epstein became an enemy alien and spent a short time in prison; once free, he was still not allowed to leave Germany. It was during this period that he worked on the theory of the Stark Effect. Following the war, Epstein moved to Leiden where he met Robert A. Millikan who recruited him to the faculty at Caltech where he remained until his retirement in 1953 (his friend, Albert Einstein wrote one of his letters of recommendation for the post (see following lot). During his tenure at Caltech, Epstein continued his research on quantum theory and quantum mechanics. Epstein was additionally interested in psychoanalysis, and met with Freud in Switzerland c. 1910-1911, and later founded the Los Angeles Institute of Psychoanalysis. During Einstein's short tenure as a visiting professor at Caltech, the pair rekindled their friendship which led to the following body of correspondence (lots 28-39). Epstein correspondents also included Sigmund Freud, Paul Sommerfeld, Max Planck, Werner Heisenberg and Helen Dukas (lots 40-42).