Ludwig Hopf

Ludwig Hopf (23 October 1884 in Nürnberg, Germany – 23 December 1939 in Dublin, Ireland) was a German-Jewish theoretical physicist who made contributions to mathematics, special relativity, hydrodynamics, and aerodynamics. Early in his career he was the assistant to and a collaborator and co-author with Albert Einstein.

Hopf was born into a family of prominent hops merchants and municipal counselors in Nürnberg, Germany, the son of Elise (née Josephthal) and Hans Hopf. From 1902-1909 he studied math and physics at the Universities of Munich and Berlin.

Hopf studied under Arnold Sommerfeld at the University of Munich, where he received his Ph.D. in 1909, on the topic of hydrodynamics. Shortly after this, Sommerfeld introduced Hopf to Albert Einstein at a physics conference in Salzburg. Later that year, Einstein, needing an assistant at the University of Zurich, hired Hopf; it was an added bonus that Hopf was a talented pianist, since Einstein played the violin and liked to play duets. Hopf was an ardent fan of psychoanalysis, had studied Freud and, once in Zurich, attached himself to Freud's ex-disciple Carl Jung. Hopf introduced Einstein to Jung, and Einstein returned to Jung's house several times over the years. In 1910, Hopf collaborated and published with Einstein two papers on classical statistical aspects of radiation. Hopf’s collaboration with Sommerfeld on integral representations of Bessel Functions resulted in the publication of a paper in 1911. Also in that year, Hopf accompanied Einstein to the Karl-Ferdinand University in Prague; however, he did not stay with Einstein long – due to “unsanitary conditions” in Prague.

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