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 was established by the "Max-Planck Gesellschaft" (MPG, Max Planck Society, successor organization to the "Kaiser-Wilhelm Gesellschaft"). Heisenberg was appointed president of the "Deutsche Forschungsrat". In 1951, the organization was fused with the Notgemeinschaft der Deutschen Wissenschaft (NG, Emergency Association of German Science) and that same year renamed the "Deutsche Forschungsgemeinschaft" (DFG, German Research Foundation). With the merger, Heisenberg was appointed to the presidium. In 1952, Heisenberg served as the chairman of the Commission for Atomic Physics of the DFG. Also that year, he headed the German delegation to the European Council for Nuclear Research (CERN). In 1953, Heisenberg was appointed