Ernst Ising

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Ernst Ising (born May 10, 1900 in Cologne ; † May 11, 1998 in Peoria / Illinois , USA) was a German mathematician and physicist .

Life

Ernst Ising's parents were the businessman Gustav Ising and his wife Thekla, née Löwe. After graduating from the Humanist Gymnasium in Bochum and after a short military service, Ernst Ising studied mathematics, physics and astronomy in Göttingen, Bonn and Hamburg. In his doctoral thesis, which he started with Wilhelm Lenz in Hamburg in 1922 and completed in 1924, he analyzed a model proposed by his doctoral supervisor that should contribute to the understanding of ferromagnetism , the Ising model , which was later named after him . The dissertation was published in excerpts in the Zeitschrift für Physik in 1925. Because the one-dimensional version considered by Ernst Ising, a spin chain , did not describe an ordered ferromagnetism, the resigned but fortunately erroneous conclusion in the dissertation was that the model probably deserved no further special interest because of its short-range interactions (“... so we do not arrive at an explanation of ferromagnetism with our assumptions ... It therefore seems justified to conclude that one of our assumptions is incorrect ”).

After completing his doctorate, Ernst Ising worked in industry for two years (patent department of AEG) before turning to the teaching profession. He studied pedagogy and philosophy in Berlin with the teaching degree for secondary schools in 1930. From 1927 he worked at the boarding school in Salem . Then he was a study assessor in Strausberg and Crossen . In 1933 Ernst Ising was dismissed from civil service by the new rulers in Germany because of his Jewish roots. He found a job at the Jewish children's and rural school home in Caputh near Potsdam, where he replaced Fridolin Friedmann as headmaster in 1937 ; Ernst and his wife Johanna "Jane" Ising , née Ehmer, lived there in Caputh next to the now former summer house of the Albert Einstein family . In 1938 the school in Caputh was devastated by the Nazis, in 1939 the Isings emigrated to Luxembourg. In July 1939 and February 1942, the Swiss authorities refused an entry request. Ising's father lived as an emigrant in Basel. After the occupation of Luxembourg (1940) by the German Wehrmacht, Ernst Ising was obliged to do forced labor to dismantle railway tracks on the Maginot Line for over a year. In 1947 the Ising family emigrated to the USA.

Only then did Ising find out that “his” model had become the subject of intensive research. In particular, the exact solution of the model for a square lattice in two dimensions by Lars Onsager in 1944 attracted a great deal of attention in specialist circles: the model, in the multi-dimensional version, is capable of converting a material that is magnetically disordered at higher temperatures into one To describe ferromagnets, as predicted qualitatively by Rudolf Peierls in 1936 .

Ising was initially a teacher at a college in Minot (North Dakota). In 1948 he received a professorship at Bradley University in Peoria (Illinois) . He worked there for several decades until his retirement in 1976 as a university professor without, apart from a short letter to the editor about 'Goethe as a physicist', publishing in specialist journals. In 1953 he became a US citizen. In 1971 he received an award as "Outstanding Teacher of America".

An obituary from Bradley University says: Ernst was a sensitive, artistically interested man who loved travel and the arts. He had a penetrating mind and a keen sense of humor, but was of a gentle, calm character who always seemed a little embarrassed when asked about his famous model .

In 1974 he was honored by the University of Hamburg on the occasion of his golden doctoral jubilee.

effect

With its numerous variants, the Ising model has become one of the most studied models in statistical physics (and beyond). In particular, it is the starting point for fundamental descriptions of phase transitions in a number of materials with and without (e.g. "Random Bond Ising Model") impurities, from glassy (e.g. +/- J-Model or Sherrington-Kirkpatrick) -Model) and spatially modulated ( ANNNI-Modell ) structures as well as neural networks and learning processes (Hopfield-Modell). It is used to test numerical algorithms, e.g. B. from Monte Carlo simulations and transfer matrix calculations. "Simple Ising models still thrive" ( Michael E. Fisher ) seems to be an evergreen not only in statistical physics. Many experiments can be reproduced very nicely using the Ising model.

After Ernst Ising's death, the University of Hamburg awarded an "Ernst Ising Prize", which was first awarded in 2002. In addition, the University of Hamburg named a junior professorship after Ernst Ising.

literature

  • S. Kobe Ernst Ising on his 95th birthday , Physikalische Blätter, Volume 51, 1995, Issue 5, p. 426, online
  • S. Kobe Das Isingmodell - yesterday and today , Physikalische Blätter, Volume 54, Issue 10, 1998, pp. 917-920, online
  • S. Kobe Ernst Ising , Brazilian Journal of Physics, Volume 30, 2000, p. 649, pdf
  • Conley Stutz, Beverly Williams, Obituary, Physics Today, Vol. 52, 1999, No. 3, pp. 106-108
  • Stephen G. Brush History of the Lenz-Ising Model , Reviews of Modern Physics, Volume 39, 1962, pp. 883-893

Web links

Individual evidence

  1. ^ Reprinted in the Bibliotheca Augustana
  2. ^ Ising contributions to the theory of ferromagnetism , Zeitschrift für Physik, Volume 31, 1925, pp. 253-258
  3. ↑ State Archives Basel-Stadt Signature: PD-REG 3a 33766
  4. ↑ American Journal of Physics, Volume 18, Issue 4, April 1950, pp. 235-236
  5. ↑ "Ernst was a sensitive, artistic man who loved travel and the arts. He had a keen mind and sharp sense of humor, but was a gentle, quiet individual who always seemed a little shy when questioned about his famous model".
personal data
SURNAME Ising, Ernst
BRIEF DESCRIPTION German-American mathematician and physicist
DATE OF BIRTH May 10, 1900
PLACE OF BIRTH Cologne
DATE OF DEATH May 11, 1998
Place of death Peoria / IL , USA