Werner Heisenberg mechanics formulation of quantum mechanics. On 1 May 1926, Heisenberg began his appointment as a university lecturer and assistant to Bohr in Copenhagen. It was in Copenhagen, in 1927, that Heisenberg developed his uncertainty principle, while working on the mathematical foundations of quantum mechanics. On 23 February, Heisenberg wrote a letter to fellow physicist Wolfgang Pauli, in which he first described his new principle. In his paper on the principle, Heisenberg used the word ""Ungenauigkeit"" (imprecision), not uncertainty, to describe it. In 1927, Heisenberg was appointed "ordentlicher Professor" (professor ordinarius) of theoretical physics and head of the department of physics
Werner Heisenberg 1942 that they should employ 120,000 men just for building the thing up." On 3 January 1946, the 10 Operation Epsilon detainees were transported to Alswede in Germany, which was in the British occupation zone. Heisenberg settled in Göttingen, also in the British zone. In July, he was named director of the "Kaiser-Wilhelm-Institut für Physik" (KWIP, Kaiser Wilhelm Institute for Physics), then located in Göttingen. Shortly thereafter, it was renamed the Max Planck Institut für Physik, in honor of Max Planck and to assuage political objections to the continuation of the institute. In 1949, the "Deutsche Forschungsrat" (German Research Council)