was done in his laboratory where they developed guanidine perchlorate. Then he worked on the development of trench mortars. He was awarded the Iron Cross first class and later the Pour le Mérite. When the high command was considering unleashing unrestricted submarine warfare, he asked the Kaiser for an opportunity to warn about the enormous potential of the United States as an adversary. They would not listen, Ludendorff shouted him down for "incompetent nonsense." He published his book The Foundations of the New Heat Theorem. Both sons had died at the front. In 1918, after studying photochemistry, he proposed the atomic chain reaction theory. It stated that when a reaction in which free atoms are formed that can decompose target molecules into more free atoms would result in a chain reaction. His theory is closely related to the natural process of Nuclear Fission. In 1920, he and his family briefly fled abroad because he was one of the scientists on the Allied list of war criminals. Later that year he received the Nobel Prize in chemistry in recognition of his work on thermochemistry. He was elected Rector of Berlin University for 1921–1922. He set up an agency to channel government and private funds to young scientists and declined becoming Ambassador to the United States. For two unhappy years, he was the president of the Physikalisch-Technische Reichsanstalt (National Physical Laboratory), where he could not cope with the "mixture of mediocrity and red tape". In 1924, he became director of the Institute of Physical Chemistry at Berlin. In 1927, the decrease in specific heat at low temperatures was extended to gases. He studied the theories of cosmic rays and cosmology. Although a press release described him as "completely unmusical", Nernst developed an electric piano, the "Neo-Bechstein-Flügel" in 1930 in association with the Bechstein and Siemens companies, replacing the sounding board with vacuum tube amplifiers. The piano used electromagnetic pickups to produce electronically modified and amplified sound in the same way as an electric guitar. In fact, he was a pianist, sometimes accompanying Einstein's violin. In 1933, Nernst learned that a colleague, with whom he had hoped to collaborate, had been dismissed from the department because he was a Jew. Nernst immediately taxied to see Haber to request a position in his Institute, which was not controlled by the government, only to learn that Haber was moving to England. Soon, Nernst was in