M ay 1 99 6 Ernst Ising - physicist and teacher

The Ising model is one of the standard models in statistical physics. Since 1969 more than 12000 publications appeared using this model. In 1996 Ernst Ising celebrated his 96th birthday. Some biographical notes and milestones of the development of the Ising model are given. the son of the merchant Gustav Ising and his wife Thekla, nee Löwe. The family moved to Bochum (Westfall). Ernst Ising completed the Gymnasium in Bochum in 1918. Shortly after that he had to do a brief military training. In 1919 he started studying mathematics and physics at the University of Göttingen and continued his studies in Bonn and Hamburg. In Hamburg Wilhelm Lenz (1888-1957) suggested to Ising to turn to theoretical physics. Under his guidance he began investigating a model of ferromagnetism which was introduced by his supervisor in 1920 [1]. In his dissertation (1924) Ising studied the special case of a linear chain of magnetic moments, which are only able to take two positions " up " and " down " and which are coupled by interactions between nearest neighbours. He showed that spontaneous magnetization cannot be explained using this model in its one-dimensional version [2]. After receiving his doctor's degree Ising went to Berlin and worked from 1925 to 1926 in the patent office of the Allgemeine Elektrizitätsgesell-schaft (AEG). He was not satisfied with this job and decided to become a teacher. For a year he worked at the famous boarding school in Salem in South-Baden (near the lake Constance). In 1928 he returned to Berlin University to study philosophy and pedagogy. In 1930 he passed the state examinations before the school board in higher education. In the same ————————– year he married Johanna Ehmer, a doctor of economy. The couple went to Strausberg near Berlin, where Ernst Ising got a teaching position at a high school as " Studienassessor " (in Germany a holder of a higher civil service post, who has passed the necessary examinations but has not yet completed his probationary period). Later he was tranferred to Crossen on the river Oder (now: Krosno in Poland) to fill in for an ill colleague. Just after Hitler came to power in January 1933, Jewish citizens were dismissed from their jobs as civil servants. Consequently, Ernst Ising lost his position on March 31st, 1933. For one year he was unemployed, except for a short stay in Paris at a school for emigrant …