Prof. Dr. Ludwig Hopf

“Ludwig Hopf’s lodestar was truth. The finding of knowledge was what he strained all his nerves for. His remarkable gifts led him quickly from step to step, from success to success and made his name known all over the world to fellow-scientists. He was a friend of the great geniuses of his time; indeed he was one of them. His loss is irretrievable to all of us.” -- Erwin Schrödinger, Nobel Laureate, at Ludwig Hopf's funeral, 1939.

See profile authored by his son Peter Paul Hopf under the "Media" tab, along with photos and other documents.

Detailed biographic profile: https://ulir.ul.ie/bitstream/handle/10344/4716/Holfter_2015_Hopf.pd...

Ludwig Hopf (1884 in Nürnberg, Germany – December 21, 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 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, at a physics conference in Salzburg, Sommerfeld introduced Hopf to Albert Einstein. 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. In 1910, he 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. He accepted a position at the Aachen Technische Hochschule, where he eventually became a professor in hydrodynamics and aerodynamics. During World War I, he contributed to the design of military aircraft. It was during his tenure at Aachen that he made a contribution to the Handbuch der Physik and co-authored a “highly esteemed” book on aerodynamics.

In 1933, with the Nazis coming to power in Germany, Hopf was put on leave at Aachen due to his being a Jew, and in 1934 lost his position entirely.[1]

Hopf remained in Germany until 1939 and escaped the Nazi regime only at the last minute.[2] The S.S. was seeking to arrest him and were thwarted by his son Arnold posing as his father. [3]. Arnold was arrested and sent to the Buchenwald concentration camp, from which he was able to escape after 3-4 weeks and emigrate to Kenya.[4] Ludwig left Germany for Great Britain with his wife and three of his children, taking a research fellowship at Cambridge. A short while later he moved to Dublin, Ireland to assume a professorship of mathematics at Trinity College. One of his colleagues there was the eminent Austrian physicist Erwin Schrödinger.

Shortly after taking up duties at Trinity, Hopf became seriously ill and died of thyroid failure on December 21, 1939. At his graveside, Schrödinger called Hopf "a friend of the greatest geniuses of his time," then adding "Indeed, he was one of them."[5]

From https://en.wikipedia.org/wiki/Ludwig_Hopf, with added information

[1] Herbert A. Strauss and Werner Röder (general eds.), International Biographical Dictionary of Central European Emigrés 1933-1945, vol. II / Part 1: A-K, K.G. Saur, München (1983), p 538.

[2] Siegmund-Schultze, Reinhard. Mathematicians Fleeing from Nazi Germany: Individual Fates and Global Impact, Princeton University Press (2009), p. 148. http://www.maths.ed.ac.uk/~aar/papers/siegmund.pdf

[3] http://www.archiv.rwth-aachen.de/web/rea/Seite/biographien_vert_hop...

[4] Siegmund-Schultze, ibid; http://www.archiv.rwth-aachen.de/web/rea/Seite/biographien_vert_hop...

[5] http://www.irishtimes.com/opinion/an-irishman-s-diary-1.4167

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Hopf was an ardent fan of psychoanalysis, had studied Freud and once in Zurich, attached himself to ex-Freud disciple CG Jung, who was in the midst of developing his theory of a "collective unconscious." Hopf introduced Einstein to Jung, and Einstein had dinner at Jung's home several times over the years. Jung later recalled that Einstein had made a powerful impression on him and that his ideas "exerted a lasting influence on my own intellectual work."

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Papers co-authored with Albert Einstein:

   Albert Einstein and Ludwig Hopf (1910). "Über einen Satz der Wahscheinlichkeitsrechung und seine Anwendung in der Strahlungstheorie". Ann. Phys. (Leipzig) 33 (1096).

   A. Einstein and L. Hopf (1910). "Statistische Untersuchung der Bewegung eines Resonators in einem Strahlungsfeld". Ann. Phys. (Leipzig) 33 (1105).

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Story of Ludwig Hopf, as Einstein's assistant, figuring out Einstein's mathematical error in his search for "Avogadro's Number". http://io9.com/the-math-problem-that-had-einstein-asking-for-help-f...

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Einstein-Hopf drag: https://en.wikipedia.org/wiki/Einstein%E2%80%93Hopf_drag

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Ludwig Hopf was first cousins with mathematician Heinz Hopf and first cousin once removed to composer Franz Reizenstein.

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cf. also: http://www.deutsche-biographie.de/sfz33736.html