Werner Karl Heisenberg (; German: [ˈvɛʁnɐ ˈhaɪzn̩bɛʁk] ; 5 December 1901 – 1 February 1976) was a German theoretical physicist, one of the main pioneers of the theory of quantum mechanics and a principal scientist in the German nuclear program during World War II. Heisenberg published his Umdeutung paper in 1925, a major reinterpretation of old quantum theory. In the subsequent series of papers with Max Born and Pascual Jordan, during the same year, his matrix formulation of quantum mechanics was substantially elaborated. He is known for the uncertainty principle, which he published in 1927. He received the Nobel Prize in Physics in 1932 "for the creation of quantum mechanics". Heisenberg also made contributions to the theories of the hydrodynamics of turbulent flows, the atomic nucleus, ferromagnetism, cosmic rays, and subatomic particles. He introduced the concept of a wave function collapse. He was also instrumental in planning the first West German nuclear reactor at the Kernforschungszentrum Karlsruhe, together with one in Garching at the Technische Hochschule München, in 1957 (both were research reactors). Following World War II, Heisenberg was appointed Director of the Kaiser Wilhelm Institute for Physics, which soon thereafter was renamed the Max Planck Institute for Physics. He was director until it was moved to Munich in 1958. He was Director of the Max Planck Institute for Physics and Astrophysics from 1960 to 1970. Heisenberg was also President of the German Research Council, Chairman of the Commission for Atomic Physics, Chairman of the Nuclear Physics Working Group, and President of the Alexander von Humboldt Foundation.
Early life and education
Early years Werner Karl Heisenberg was born in Würzburg, Germany, the son of Kaspar Ernst August Heisenberg and Annie Wecklein. His father was a secondary school teacher of classical languages who became Germany's only ordentlicher Professor (ordinarius professor) of medieval and modern Greek studies in the university system. Heisenberg was raised and lived as a Lutheran Christian. In his late teenage years, Heisenberg read Plato's Timaeus while hiking in the Bavarian Alps. He recounted philosophical conversations with his fellow students and teachers about understanding the atom while receiving his scientific training at the Ludwig-Maximilians-Universität München, the University of Göttingen, and the University of Copenhagen. Heisenberg later stated that "My mind was formed by studying philosophy, Plato and that sort of thing" and that "Modern physics has definitely decided in favor of Plato. In fact the smallest units of matter are not physical objects in the ordinary sense; they are forms, ideas which can be expressed unambiguously only in mathematical language". In 1919, Heisenberg arrived in Munich as a member of the Freikorps to fight the Bavarian Soviet Republic established a year earlier. Five decades later he recalled those days as youthful fun, like "playing cops and robbers and so on; it was nothing serious at all"; his duties were restricted to "seizing bicycles or typewriters from 'red' administrative buildings", and guarding suspected "red" prisoners.
University studies
From 1920 to 1923, he studied physics and mathematics at the Ludwig-Maximilians-Universität München under Arnold Sommerfeld and Wilhelm Wien and at the University of Göttingen with Max Born and James Franck and mathematics with David Hilbert. He received his doctorate in 1923 at the Ludwig-Maximilians-Universität München under Sommerfeld. In June 1922, Sommerfeld took Heisenberg to Göttingen to attend the Bohr Festival, because Sommerfeld had a sincere interest in his students and knew of Heisenberg's interest in Niels Bohr's theories on atomic physics. At the event, Bohr was a guest lecturer and gave a series of comprehensive lectures on quantum atomic physics and Heisenberg met Bohr for the first time, which had a lasting effect on him. Heisenberg's doctoral thesis, the topic of which was suggested by Sommerfeld, was on turbulence; the thesis discussed both the stability of laminar flow and the nature of turbulent flow. The problem of stability was investigated by the use of the Orr–Sommerfeld equation, a fourth-order linear differential equation for small disturbances from laminar flow. He briefly returned to this topic after World War II. At Göttingen, under Born, he completed his habilitation in 1924 with a Habilitationsschrift (habilitation thesis) on the anomalous Zeeman effect. In his youth, he was a member and Scoutleader of the Neupfadfinder, a German Scout association and part of the German Youth Movement. In August 1923, Robert Honsell and Heisenberg organized a trip to Finland with a Scout group of this association from Munich.
Personal life
Heisenberg enjoyed classical music and was an accomplished pianist; playing for others was a prominent part of his social life. During the late 1920s and early 1930s he would often play music and dance at the Berlin home of his aristocratic student Carl Friedrich von Weizsäcker, during which time he carried on a courtship with Carl's high-school-age sister Adelheid, which led to him being unwelcome at their home for a time. Years later, his interest in music also led to meeting his future wife. In January 1937, Heisenberg met Elisabeth Schumacher (1914–1998) at a private music recital. Schumacher was the daughter of a well-known Berlin economics professor, and her brother was the economist E. F. Schumacher, author of Small Is Beautiful. Heisenberg and Schumacher were married on 29 April. Fraternal twins Maria and Wolfgang were born in January 1938, whereupon Wolfgang Pauli congratulated Heisenberg on his "pair creation"—a wordplay on a process from elementary particle physics, pair production. They had five more children over the next 12 years: Barbara, Christine, Jochen, Martin and Verena. In 1939 he bought a summer home for his family in Urfeld am Walchensee, in southern Germany. One of Heisenberg's sons, Martin Heisenberg, became a neurobiologist at the University of Würzburg, while another son, Jochen Heisenberg, became a physics professor at the University of New Hampshire.
Academic career
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