Wilhelm Lenz

Wilhelm Lenz (February 8, 1888 in Frankfurt-am-Main, Germany – April 30, 1957 in Hamburg, Germany) was a German physicist, most notable for his invention of the Ising model [cite journal | last = Lenz | first = W | authorlink = Wilhelm Lenz | year = 1920 | title = Beiträge zum Verständnis der magnetischen Eigenschaften in festen Körpern | journal = Physikalische Zeitschrift | volume = 21 | pages = 613–615] and for his application of the Laplace-Runge-Lenz vector to the (old) quantum mechanical treatment of hydrogen-like atoms. [cite journal | last = Lenz | first = W | authorlink = Wilhelm Lenz | year = 1924 | title = Über den Bewegungsverlauf und Quantenzustände der gestörten Keplerbewegung | journal = Zeitschrift für Physik | volume = 24 | pages = 197–207 | doi = 10.1007/BF01327245]

In 1906, Lenz graduated from the Klinger-Oberralschule, a non-classical secondary school in Frankfurt-am-Main, and went to study mathematics and physics at the University of Göttingen. From 1908 to 1911, Lenz studied under Arnold Sommerfeld, at the University of Munich, and he was granted his doctorate [ [http://genealogy.math.ndsu.nodak.edu/html/id.phtml?id=66700 Lenz] – Mathematics Genealogy Project. 1911 Dissertation title: "Über das elektromagnetische Wechselfeld der Spulen und deren Wechselstrom-Widerstand, Selbstinduktion und Kapazität".] on March 2, 1911. Upon graduation, he stayed on at the University, became Sommerfeld’s assistant on April 1, 1911, and he completed his Habilitation on February 20, 1914, becoming a Privatdozent on April 4, 1914. During World War I, he served as a radio operator in France and was awarded the Iron Cross Second Class in 1916. From September 30, 1920, he was again an assistant to Sommerfeld at the University of Munich’s Institute of Theoretical Physics, and he was appointed to the title and rank of extraordinarius professor at the University, on November 11, 1920. On December 1, 1920 he became an extraordinarius professor at the University of Rostock. From 1921, until his retirement in 1956, he was at the University of Hamburg, as Ordinarius Professor of Theoretical Physics and Director of the Institute of Theoretical Physics. [ Mehra, Volume 1, Part 1, p. 334.] [ [http://www.amphilsoc.org/library/guides/ahqp/ Author Catalog: Lenz] – American Philosophical Society] [ [http://www.ethbib.ethz.ch/exhibit/pauli/lenz.html Lenz] - ETH Zurich] [ [http://litten.de/fulltext/lenz.htm Lenz Biography] – Litten]

The formation of the new chair and institute for theoretical physics at Hamburg was a result of advances being made in Germany on atomic physics and quantum mechanics and the personal intervention of Sommerfeld, who helped many of his students get such professorships. [ Other examples besides Lenz at Hamburg, include Peter Debye at the University of Zurich, Adolf Kratzer at the University of Münster, and Erwin Fues at the University of Stuttgart, where Sommerfeld’s former student Paul Peter Ewald was already in place. When they were called to other facilities, these personnel effectively became extensions of Sommerfeld’s Institute of Theoretical Physics. See Mehra, Volume 1, Part 1, 1982, p. 335 and Mehra, Volume 5, Part 1, 2001, p. 249.]

At Hamburg, Lenz trained Ernst Ising and J. Hans D. Jensen; his assistants there included Wolfgang Pauli [ Pauli began as Hilfsassistent to Lenz at Hamburg on April 1, 1922. He also completed his Habilitation there. Both Lenz and Otto Stern knew of Pauli’s abilities. The mathematician Erich Hecke was dean of the faculty at the time. Hecke waived the normal trail lecture and the colloquium for Habilitation, in recognition of his abilities. The "venia legendi" was conferred on Pauli and he gave his inaugural lecture on February 23, 1924. See Mehra, Volume 1, Part 2, pp. 487 and 672.] Pascual Jordan, [ In 1923, Jordan went to the University of Göttingen and was instrumental in helping Max Born in founding the matrix mechanics formulation of quantum mechanics in 1925, from a paper by Werner Heisenberg given to Born, in July of that year, for review and publication.] and Albrecht Unsöld. [ Unsöld was a former doctoral student of Sommerfeld, who got his degree in 1927. See [http://genealogy.math.ndsu.nodak.edu/html/id.phtml?id=66706 Unsöld] – Mathematics Genealogy Project.] Together with Pauli and Otto Stern, Lenz built up the Institute into an international center for nuclear physics. They maintained close scientific and personal exchanges with the institutes for theoretical physics at the Universities in Munich (Sommerfeld), Göttingen (Max Born), and Copenhagen (Niels Bohr). [ [http://litten.de/fulltext/lenz.htm Lenz Biography] – Litten] [ [http://www.ethbib.ethz.ch/exhibit/pauli/lenz.html Lenz] - ETH Zurich]

When Lenz retired in 1956 he was succeeded by Harry Lehmann.

Books

*Wilhelm Lenz "Einführungsmathematik für Physiker" (Verlagsanstalt Wolfenbüttel, 1947)

References

*Mehra, Jagdish, and Helmut Rechenberg "The Historical Development of Quantum Theory. Volume 1 Part 1 The Quantum Theory of Planck, Einstein, Bohr and Sommerfeld 1900 – 1925: Its Foundation and the Rise of Its Difficulties. "(Springer, 2001) ISBN 0-387-95174-1

*Mehra, Jagdish, and Helmut Rechenberg "The Historical Development of Quantum Theory. Volume 1 Part 2 The Quantum Theory of Planck, Einstein, Bohr and Sommerfeld 1900 – 1925: Its Foundation and the Rise of Its Difficulties." (Springer, 2001) ISBN 0-387-95175-X

*Mehra, Jagdish, and Helmut Rechenberg "The Historical Development of Quantum Theory. Volume 5 Erwin Schrödinger and the Rise of Wave Mechanics. Part 1 Schrödinger in Vienna and Zurich 1887-1925." (Springer, 2001) ISBN 0-387-95179-2

Notes