Minkowski, Rudolf (1895 - 1976)

Rudolf Leo Bernhard Minkowski was born in Strasbourg on May, 28th 1895 and died in Berkeley, California, on January 4th 1976. He was the son of Oskar Minkowski, a professor for pathology. Rudolf married Luise Amalie David (1902 - 1978) in Leipzig, Germany, in 1926. They had one daughter and one son, Eva and Hermann.

Minkowski went to school in Köln (Cologne), Greifswald, and Breslau. He started to study Physics at the University of Breslau in 1913 and planned to go to Berlin after the first year. These plans were disturbed by the war from 1914 to 1918, in which he served in the German Army. After the war he studied in Berlin, returned to Breslau, finished his studies and wrote his doctoral thesis under the supervision of Rudolf Ladenburg in 1921. After working in Goettingen for a year with James Franck and Max Born he moved to Hamburg in October 1922 and worked at the University there until 1935 when he left for the United States. From 1935 until 1960 he worked at the Mt. Wilson and Mt. Palomar Observatories as a research astronomer and from 1961 to 1965 at the University of California in Berkeley.

Minkowskis emigration was not planned. In 1933 Hitler took over power in Germany. The 'National Socialist Party of Germany' changed several laws, allowing only persons with aryan ancestors in official places like universities. In 1935 Minkowski lost his title of professor and was no longer allowed to teach. From then on he worked in Hamburg as an normal employee. His father-in-law, judge Alfons David at the court in Leipzig, was dismissed as early as 1933. Walter Baade, who had left Hamburg and was working at the Mt. Wilson Observatory since 1931, had made available a post for Minkowski as research assistant. He accepted and took a year leave from Hamburg, planning to return after this time. In California Minkowski received a letter from the University of Hamburg, informing him that he will be dismissed by April, 1st 1936. Within this year Minkowski was offered to stay at Mt. Wilson as a regular staff member. Later, in making good for the loss of his title under the national socialistic regime, Minkowski was appointed professor emeritus of the University of Hamburg, effective January 1954.

Minkowskis work can be divided into two phases. Prior to his emigration he worked on spectroscopic problems, in the US he made outstanding observations in the field of Astronomy and Radioastronomy. His doctoral thesis was the first paper of a series on specific problems in spectroscopy. These papers were in part prepared together with his teacher Ladenburg and published in the magazine for physics (Zeitschrift fuer Physik). Minkowskis main topic was the width of spectral lines, broadened by pressure and self absorption. Beside that he published papers on the behavior of electrons in metal vapor and the process of electrons passing through atoms (together with Hertha Sponer, 1924). Until 1935 Minkowski published 17 papers and two additional articles in books on physics. His last paper during his time in Hamburg described the atom beam method for determining the fine structure of spectral lines (Die Intensitaetsverteilung der im Molekularstrahl erzeugten Spektrallinien). This paper was published together with H. Bruck.

As early as 1933 Minkowski had worked on an astronomical problem, the structure of features in the spectrum of the Orion nebula (M42). In the US his knowledge on spectroscopy was most useful while studying astronomical objects. The close collaboration with Walter Baade, who emigrated to the US from Hamburg in 1931, led to a very rapidly growing number of publications. These include further investigations on the Orion nebula, systematic studies on supernovae in other galaxies and supernova remnants in our Milky Way. Minkowskis classification of Supernovae into type I and type II described a useful tool in determining the distances in space (ApJ 89, 156 [1939] and PASP 53, 224 [1941]). Shortly after the Crab nebula was discovered to be a supernova remnant by Oort and Mayall, Minkowski and Baade identified the small central star. Minkowski also worked on the distribution of emission nebula in our galaxy and on the spectral features of comets. He discovered the comet 1950 b Minkowski. Another celestial object carries his name: Minkowskis Footprint. It is a small and faint nebula (3" by 8") in the constellation of Cygnus.

From 1950 on radio astronomy caught the attention of Minkowski. Together with Walter Baade he started to locate optical counterparts to new found radio sources. The first extragalactic optical counterpart found for a radio source was Cygnus A in 1954. Later he also worked on the distribution of galaxies in space and found in 1960 the galaxy (3C 295) with the then highest redshift at z=0.48 (ApJ 132, 908 [1960]) An anecdote tells that he developed the plate the same night and, after finding the high redshift, joined other astronomers in the library of the 200 inch dome with a bottle of Whisky; the rest of the night was declared 'overcast'. The spectrum was made during the very last observing night Minkowski had at the 200 inch telescope. This redshift remained the highest for 15 years until Quasars were found. Minkowski was responsible for the photographic sky survey of the National Geographic Society at Mt. Palomar, today known as the POSS, the Palomar Observatory Sky Survey. This work was done with the 48" Schmidt camera on Mt. Palomar and covered the northern hemisphere from the celestial north pole to -33 deg. latitude.

After his retirement from the Mt. Wilson and Mt. Palomar observatories he received an invitation from the Radio Astronomical Laboratory in Berkeley. There he worked from 1961 to 1965, then retiring the second time.

Minkowski was member of the Royal Astronomical Society, the US National Academy of Sciences; he received the Bruce Medal of the Astronomical Society of the Pacific in 1961 and a Dr. h.c. at Berkeley in 1968. Click here for List of Bruce Medallists.

1. RECHENBERG, H., in: Neue Deutsche Biographie, Bd. 17, p. 540.
2. OVERBYE, D., Lonely Hearts of the Cosmos, [1991] p. 63-66.
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