Walter Gerlach

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Commemorative plaque at the building of the Physical Society

Walther Gerlach (born August 1, 1889 in Biebrich am Rhein ; died August 10, 1979 in Munich ) was a German physicist and university lecturer.


Walther Gerlach was born in Biebrich, the son of the hygienist Valentin Gerlach and his wife Marie, née Niederhaeuser (1863–1941). He is the older brother of pathologist Werner Gerlach and doctor Wolfgang Gerlach (twins).

Gerlach began his studies at the Eberhard Karls University of Tübingen in 1908 and became active in the Corps Borussia Tübingen . In 1912 he received his doctorate under Friedrich Paschen . re. of course received his doctorate and his habilitation in 1916. At that time he was working on the measurement of the Stefan-Boltzmann constant .

On August 24, 1915, Gerlach was drafted into the Goisberg barracks in Ulm as a Landsturm recruit for the Reserve Infantry Regiment 247 reserve battalion. He had not previously done military service. On December 4, 1915, he was released to Tübingen because of illness; he continued to work on his habilitation. On May 11, 1916, he was drafted again. Max Wien , who had done research in the field of wireless telegraphy, brought him to Jena to do research on communications equipment for the war. In the fall of 1916, Gerlach under Colonel Beatings with the VI. Army participated in battles in Flanders and Artois. As a technical officer, he did not do military service, but was directly confronted with what was happening in the war. On December 3, 1916 (late) signs of appendicitis were discovered, which broke through. He underwent surgery on December 6th. On June 20, 1918 he was sent to the Western Front to Fliegerabteilung 274 (artillery). There he was employed as a radio operator in an infantry escort battery and took part in battles at Dun-sur-Meuse . Soon after his arrival he contracted the Spanish flu and was hospitalized until August 25, 1918. After that he was with the Stahnsdorf radio test company .

From 1917 he was a private lecturer at the Georg-August University in Göttingen . In 1919/20 he worked in the physical laboratory of the Elberfeld paint factory (later Bayer AG). In 1921 he became an associate professor at the new Johann Wolfgang Goethe University in Frankfurt am Main with Richard Wachsmuth . After Otto Stern had had the idea for a fundamental experiment in 1921, with which one could use so-called directional quantization to experimentally distinguish between the classical and the quantum view of the magnetic moment of particles, Stern and Gerlach conceived the practical implementation of what is now known as the Stern-Gerlach Experiment known experimental setup. The experiment was successfully carried out by Gerlach in Frankfurt in February 1922. Gentner writes that this experiment, the result of which Niels Bohr "unlike others" correctly predicted (which is why Gerlach communicated the result of the experiment in a telegram to Stern in Rostock with the words Bohr is right ), was a " maximum "art of experimentation". and further "this proved the directional quantization". On a postcard sent to Gerlach on February 17, 1922 by the critical theorist Wolfgang Pauli, Pauli wrote "Now hopefully even the unbelieving star will be convinced of directional quantization" . Gerlach was nominated for the Nobel Prize in Physics for this work, together with Stern, in 1925 and in eleven further years , but never received it. According to Horst Schmidt-Böcking , the Nobel Committee probably had concerns about compromising itself because of Gerlach's involvement in the Reich Research Council and the uranium project towards the end of the war. In 1944, when the Nobel Prize for Stern was being discussed, the influential physicist Manne Siegbahn suggested him. The Stern-Gerlach experiment was not explicitly mentioned in the official justification for Stern, but it certainly played a decisive role, as the appreciation by committee member Erik Hulthén on Swedish radio in 1944 showed. Schmidt-Böcking reconstructed the original experimental setup for the Stern-Gerlach experiment; the original was lost in World War II. The reconstruction and surviving originals (a Stern microscope and vacuum pumps) were shown at an anniversary exhibition at the University of Frankfurt in 2014.

In 1924/25 he returned to Tübingen as a professor and successor to Paschen, partly on the recommendation of Albert Einstein . In 1929, Gerlach received the Chair of Experimental Physics at the Ludwig-Maximilians-Universität in Munich , succeeding Wilhelm Wien (at the special instigation of Arnold Sommerfeld ). He held the chair until his retirement in 1957. He was director of the 1st Physics Institute at the University of Munich. In 1940 he was elected a member of the Leopoldina . From 1943 he headed the physics department and the working group for nuclear physics in the Reich Research Council . Initially he was the Reich Marshal's representative for nuclear physics for the German uranium project , and from 1944 he was the representative for nuclear physics . As part of this, he also fetched a number of young physicists from the front. At the end of the war he was interned at Farm Hall by the Allies as part of Operation Epsilon . From 1946 to 1948 he was a professor at the University of Bonn. From 1948 to 1951 he was rector of the Ludwig Maximilian University, where he rebuilt the physics institute. From 1949 to 1951 he was also the first President of the Fraunhofer Society . From 1951 to 1961 he was Vice President of the German Research Foundation (DFG) and from 1956 to 1957 President of the German Physical Society (DPG). From 1937 to 1946 Gerlach was a member of the Senate of the Kaiser Wilhelm Society .

After the war he was active in the reconstruction of the natural sciences in Germany. He was involved in setting up the Studienstiftung des Deutschen Volkes , was a senator of the Max Planck Society and was involved in setting up the Physikalisch-Technische Bundesanstalt in Braunschweig. Gerlach was a co-initiator and signatory of the Tübingen Resolution of October 1, 1951: The demand for increased performance, which was justified after 1945, was in danger of suffocating intellectual life through the abundance of material. "The penetration of the essentials of the subjects has the absolute priority over any expansion of the material area." In 1957 he signed the declaration of the Göttingen Eighteen , a group of 18 nuclear physicists who opposed the planned nuclear armament of the Bundeswehr .

He determined radiation pressure with Alice Golsen in 1923 . He also dealt with the temperature dependence of magnetic properties with applications in industry, the relationship between atomic structure and magnetism, the photoelectric effect , thermal radiation and he determined Bohr's magneton . In 1930–1936 he published a three-volume monograph on quantitative chemical spectral analysis . He later worked on natural and man-made (atom bomb tests in the 1950s) radioactivity in the environment. In public lectures in the 1950s, he advocated stopping atomic bomb testing.

Gerlach wrote a number of popular science books on physics and biographies of Otto Hahn (whom he was a close friend of for many years), Johannes Kepler and Michael Faraday . He was the editor of the Fischer Lexicon of Physics and wrote sections on the history of physics in the Propylaea World History . Gerlach was deeply involved with Kepler for a long time and was chairman of the Kepler Society in Kepler's birthplace, Weil der Stadt , from 1962–1972 . In Munich he was known for the large experimental physics lectures, with demonstration experiments that came close to the well-known Göttingen lecture by Robert Wichard Pohl .

Gerlach's first marriage was to Mina Metzger (born 1889) on September 29, 1917; they had a daughter Ursula (born 1918). In his second marriage (Munich, April 18, 1939) he was with the pediatrician Dr. medical Ruth Probst (1905–1994) married. He died in Munich in 1979 and was buried in the forest cemetery there.


Walther Gerlach.JPG

Publications (selection)

  • The chemical emission spectral analysis. 3 volumes. Voss, Leipzig 1930, 1933, 1936.
  • The experimental foundations of quantum theory. Vieweg, Braunschweig 1921. ( digital copy at )
  • Atomic decomposition and atomic construction: the physical analysis of atoms. Fischer, Jena 1923.
  • Matter, electricity, energy: principles and results of experimental atomic research. Steinkopff, Dresden 1926.
  • The importance of the purest iron in crystallized form for the problem of ferromagnetism. In: Wilhelm Geibel (ed.): Festschrift for the 70th birthday of Dr. phil. dr eng. Hey Wilhelm Heraeus. GM Albertis Hofbuchhandlung Bruno Clauss, Hanau 1930, pp. 27-33.
  • The free electron. In: Carl Ramsauer (ed.): The free electron in physics and technology. Springers, 1940.
  • The quantum theory: Max Planck, his work and its impact. With a bibliography of the works of Max Planck. University Press, Bonn 1948.
  • Capacity speaks. In: G. Lehner (ed.): Authority - what is it today? Controversial claims to power in the state, society and culture. Munich 1965, pp. 121–135.
  • as ed.: Loosening the tongue of nature: life and achievement of great researchers. Ehrenwirth, Munich 1967; 2nd edition ibid 1969 (= the modern non-fiction book. Volume 84).
  • with Martha List: Johannes Kepler . 2nd Edition. Piper, Munich 1980, ISBN 3-492-00501-2 .
  • with Dietrich Hahn : Otto Hahn . A life of research in our time. Scientific publishing company, Stuttgart 1984, ISBN 3-8047-0757-2 .
  • as editor, with the collaboration of Josef Brandmüller: The Fischer Lexicon. Part 19: Physics. New edition 239.–243. Thousand. Fischer Paperback Publishing House, Frankfurt am Main 1978, ISBN 3-596-40019-8 .
  • MR. Bachmann, Helmut Rechenberg (ed.): Walther Gerlach (1889–1979). A selection from his writings and letters. Springer Verlag, 1989.
  • Physics of Daily Life - A Guide to Physical Thinking and Understanding Physical Evolution. Springer, 1957; Fischer Library, 1971.
  • Michael Faraday (1791–1867) On the 100th anniversary of his death. Oldenburg, 1968.
  • The language of physics. Dummler, Bonn 1962.
  • humanity and scientific research. Vieweg 1962.
  • Physics in intellectual history and education. Aulis, Cologne 1964.

See also


web links

Commons : Walther Gerlach  - Collection of images, videos and audio files


  1. a b c Grave of the Gerlach family in the Munich forest cemetery (grave field 108, location , pictures )
  2. Kösener Corpslisten 1930, 127/340; retired after World War II.
  3. Josef Georg Huber: WALTHER GERLACH (1889 - 1979) and his path to becoming a successful experimental physicist until around 1925 (2014); pp. 179-187.
  4. Bretislav Friedrich and Dudley Herschbach, "Stern and Gerlach: How a Bad Cigar Helped Reorient Atomic Physics" in Physics Today, 56, 12, 53 (2003); doi:10.1063/1.1650229
  5. a b c d e f g Wolfgang Gentner: Commemorative Words for Walther Gerlach, Order Pour le Mérite , Volume 16, 1980, pp. 47-53
  6. Nomination Database. Nobelstiftung , retrieved 13 July 2019 (Stern and Gerlach were jointly nominated for the Nobel Prize in 1925, 1927–1932, 1934, 1936, 1937, 1940 and 1944. Stern received it in 1944 (for 1943).).
  7. Horst Schmidt-Böcking, Interview in Forschung Frankfurt, No. 1, 2014, p. 75
  8. Horst Schmidt-Böcking, Alan Templeton, Wolfgang Trageser (eds.), Otto Sterns Collected Letters, Volume 2, Springer 2019, p. 344. It is also stated there that it cannot be proven that Gerlach's transfer to his role was due to the time of National Socialism.
  9. The Forgotten Nobel Prize Winner , Frankfurter Rundschau, December 28, 2010. Otto Stern is meant. Schmidt-Böcking's replica was in his office at the time. He only has an original Stern microscope, which he received from his niece.
  10. Otto Stern , Frankfurter Personenlexikon 2019
  11. Text of the 1957 Göttingen Declaration at
  12. Holger Krahnke: The members of the Academy of Sciences in Göttingen 1751-2001 (= treatises of the Academy of Sciences in Göttingen, philological-historical class. Episode 3, vol. 246 = treatises of the Academy of Sciences in Göttingen, mathematical-physical class. Episode 3, Vol. 50). Vandenhoeck & Ruprecht, Goettingen 2001, ISBN 3-525-82516-1 , p. 91.