Göttingen In October 1893, Sommerfeld went to the
University of Göttingen, which was the center of mathematics in Germany. There, he became an assistant to
Theodor Liebisch at the Mineralogical Institute, through a fortunate personal contact—Liebisch had been a professor at the University of Königsberg and a friend of the Sommerfeld family. In September 1894, Sommerfeld became
Felix Klein's assistant, which included taking comprehensive notes during Klein's lectures and writing them up for the Mathematics Reading Room, as well as managing the reading room. was completed under Klein in 1895, which allowed Sommerfeld to become a
Privatdozent at Göttingen. As a
Privatdozent, he lectured on a wide range of mathematical and mathematical physics topics. His lectures on partial differential equations were first offered at Göttingen, Lectures by Klein in 1895 and 1896 on rotating bodies led Klein and Sommerfeld to write a four-volume text
Die Theorie des Kreisels – a 13-year collaboration, 1897–1910. The first two volumes were on theory, and the latter two were on applications in geophysics, astronomy, and technology. at Göttingen. In October 1897, Sommerfeld was appointed Professor of Mathematics at the
Bergakademie Clausthal (now the
Clausthal University of Technology) in
Saxony; he was successor to
Wilhelm Wien. This appointment provided enough income to eventually marry Johanna.
Munich From 1906, Sommerfeld established himself as Ordinarius Professor of Physics and director of the new Theoretical Physics Institute at the
Ludwig-Maximilians-Universität München (LMU Munich). He was selected for these positions by
Wilhelm Röntgen, Director of the Physics Institute at Munich, which was looked upon by Sommerfeld as being called to a "privileged sphere of action". After getting their doctorates with Sommerfeld,
Wolfgang Pauli,
Werner Heisenberg and
Walter Heitler became Born's assistants and made significant contributions to the development of quantum mechanics, which was then in very rapid development. During his 32 years of teaching at Munich, Sommerfeld taught general and specialized courses, as well as holding seminars and colloquia. For the seminar and colloquium periods, students were assigned papers from the current literature and they then prepared an oral presentation. Four of Sommerfeld's doctoral students,
Werner Heisenberg,
Wolfgang Pauli,
Peter Debye and
Hans Bethe, went on to win
Nobel Prizes, while others, most notably,
Walter Heitler,
Rudolf Peierls,
Karl Bechert,
Hermann Brück,
Paul Peter Ewald,
Eugene Feenberg,
Herbert Fröhlich,
Erwin Fues,
Ernst Guillemin,
Helmut Hönl,
Ludwig Hopf,
Adolf Kratzer,
Otto Laporte,
Wilhelm Lenz,
Karl Meissner,
Rudolf Seeliger,
Ernst C. Stückelberg,
Heinrich Welker,
Gregor Wentzel,
Alfred Landé and
Léon Brillouin, became famous in their own right. Three of Sommerfeld's postdoctoral supervisees,
Linus Pauling,
Isidor I. Rabi and
Max von Laue, won Nobel Prizes, and ten others,
William Allis,
Edward Condon,
Carl Eckart,
Edwin C. Kemble,
William V. Houston,
Karl Herzfeld,
Walther Kossel,
Philip M. Morse,
Howard Robertson and
Wojciech Rubinowicz, went on to become famous in their own right.
Walter Rogowski, an undergraduate student of Sommerfeld at
RWTH Aachen, also went on to become famous in his own right.
Max Born believed Sommerfeld's abilities included the "discovery and development of talents".
Albert Einstein told Sommerfeld: "What I especially admire about you is that you have, as it were, pounded out of the soil such a large number of young talents." While at Munich, Sommerfeld came in contact with the
special theory of relativity by
Albert Einstein, which was not yet widely accepted. His mathematical contributions to the theory helped its acceptance by the skeptics. In 1914 he worked with
Léon Brillouin on the propagation of electromagnetic waves in dispersive media. He became one of the founders of
quantum mechanics; some of his contributions included co-discovery of the
Sommerfeld–Wilson quantization rules (1915), a
generalization of
Bohr's atomic model, introduction of the Sommerfeld
fine-structure constant (1916), co-discovery with
Walther Kossel of the
Sommerfeld–Kossel displacement law (1919), and publishing
Atombau und Spektrallinien (1919), which became the "bible" of atomic theory for the new generation of physicists who developed atomic and quantum physics. The book underwent 4 editions from 1919 to 1924, to incorporate the latest advances in quantum mechanics, before splitting into two volumes. In 1918, Sommerfeld succeeded Einstein as Chair of the
Deutsche Physikalische Gesellschaft (DPG). The scientific papers published in DPG journals became so voluminous, that in 1919 a committee of the DPG recommended the establishment of
Zeitschrift für Physik for publication of original research articles, which commenced in 1920. Since any reputable scientist could have their article published without refereeing, time between submission and publication was very rapid – as fast as two weeks. This greatly stimulated the scientific theoretical developments, especially that of quantum mechanics in Germany at that time, as this journal was the preferred publication vehicle for the new generation of quantum theorists with avant-garde views. In the winter semester of 1922/1923, Sommerfeld gave the Carl Schurz Memorial Professor of Physics lectures at the
University of Wisconsin–Madison. In 1927, Sommerfeld applied
Fermi–Dirac statistics to the
Drude model of
electrons in metals – a model put forth by
Paul Drude. The new theory solved many of the problems predicting thermal properties the original model had and became known as the
Drude–Sommerfeld model. In 1928/1929, Sommerfeld traveled globally, with major stops in India, China, Japan, and the United States. Sommerfeld was a great theoretician; besides his invaluable contributions to quantum theory, he worked in other fields of physics, such as the classical theory of electromagnetism. For example, he proposed a solution to the problem of a radiating hertzian
dipole over a conducting earth, which over the years led to many applications. His
Sommerfeld identity and Sommerfeld integrals are to the present day the most common way to solve this kind of problem. Also, as a mark of the prowess of Sommerfeld's school of theoretical physics and the rise of theoretical physics in the early 1900s, as of 1928, nearly one-third of the ordinarius professors of theoretical physics in the German-speaking world were students of Sommerfeld. On 1 April 1935, Sommerfeld achieved
emeritus status. He remained as his own temporary replacement during the selection process for his successor, which took until 1 December 1939. The process was lengthy due to academic and political differences between the Munich Faculty's selection and that of both the
Reichserziehungsministerium (REM – Reich Education Ministry) and the supporters of , which was
anti-Semitic and had a bias against
theoretical physics, especially including
quantum mechanics. The appointment of
Wilhelm Müller – who was not a theoretical physicist, had not published in a physics journal, and was not a member of the DPG – as a replacement for Sommerfeld, was considered such a travesty and detrimental to educating a new generation of physicists that both
Ludwig Prandtl, director of the
Kaiser-Wilhelm-Institut für Strömungsforschung (Kaiser Wilhelm Institute for Flow Research), and
Carl Ramsauer, director of the research division of
Allgemeine Elektrizitäts-Gesellschaft (General Electric Company) and President of the DPG, made reference to this in their correspondence to officials in the Reich. In an attachment to Prandtl's 28 April 1941 letter to Reich Marshal
Hermann Göring, Prandtl referred to the appointment as "sabotage" of necessary theoretical physics instruction. In an attachment to Ramsauer's 20 January 1942 letter to Reich Minister
Bernhard Rust, Ramsauer concluded that the appointment amounted to the "destruction of the Munich theoretical physics tradition". As for Sommerfeld's once patriotic views, he wrote to Einstein shortly after Hitler took power: "I can assure you that the misuse of the word ‘national’ by our rulers has thoroughly broken me of the habit of national feelings that was so pronounced in my case. I would now be willing to see Germany disappear as a power and merge into a pacified Europe." Sommerfeld was awarded many honors in his lifetime, such as the
Lorentz Medal, the
Max Planck Medal, and the
Oersted Medal, and election to the
Royal Society, the
National Academy of Sciences, the
Academy of Sciences of the USSR, the
Indian Academy of Sciences, and other academies including those in Berlin, Munich, Göttingen, and Vienna, as well as having conferred on him numerous honorary degrees from universities including Rostock, Aachen, Calcutta, and Athens. He was nominated for the Nobel Prize 84 times, more than any other physicist (including
Otto Stern, who got nominated 82 times), but he never received the award. Sommerfeld died on 26 April 1951 in
Munich from injuries after a traffic accident while walking with his grandchildren. The accident occurred at the corner of
Dietlindenstraße and
Biedersteiner Straße, near his house which was located at
Dunantstraße 6. He is buried at the
Nordfriedhof, close to where he lived at the time. ==Works==