Walt (h) there Gerlach (Biebrich, 1 August 1889 – Munich, 10 August 1979) was a German physicist who, together with Otto Stern discovered that the spin in a magnetic field also had a quantum of energy.
Gerlach from 1908 studied at the University of Tübingen and received his doctorate in 1912, under Friedrich Paschen. After his PhD he continued his work as an Assistant to Paschen on. From 1915 to 1918, during the first world war, he served in the German army where he worked on, among other things, radio-telegraphy in Jena under Max Wien.
After his Habilitation in 1916, he was a Privatdozent at the University of Tübingen. The next year, he became Privatdozent at the Georg-August-Universität Göttingen. From 1919 to 1920 he was the head of the physics laboratory of the IG Farbenfabrieken Elberfeld. Subsequently, he became a teaching assistant and lecturer at the Johann Wolfgang Goethe University in Frankfurt am Main, in 1921 appointed extraordinary Professor. In november that year, he led with Stern the famous Stern-Gerlach experiment , which showed that the spin in a magnetic field also had a quantum of energy. 
In 1924 he returned to Tübingen and there became full Professor, at the University where his career had begun, succeeding his teacher Paschen. In 1929 got Gerlach the Chair of experimental physics offered to theLudwig Maximilian University in Munich that was released after the death of Wilhelm Wien. He retained this position until 1945 when he was arrested by British and American allied forces because of its involvement in the nazi German atom bomb program. The reason was that Gerlach from 1943 was in charge got over the Physics Department and Association of nuclear physics in the Reichsforschungsrat (RFR, Rijksonderzoeks Council). In 1944 he was Göring's proxy for the whole Atomic Research, as a successor of Abraham Esau. Like the other captured German scientists was interned in England at Farm Hall Gerlach.
Gerlach returned in 1946 after his release back to Germany, where he was visiting professor at the University of Bonn. In 1948 he was given back his old position in Munich, a post he held until 1957. In addition, he was rector of the University from 1948 to 1951 and from 1949 to 1951 also the first President of the Fraunhofer-Gesellschaft .
1951 to 1961 he was also Vice-President of the Deutschen Forschungsgemeinschaft (DFG) from 1956 to 1957 and President of the Deutsche Physikalische Gesellschaft (DPG).