Between 1929 and 1930 Thomson was a Non-Resident Lecturer at Cornell University, Ithaca, New York. In 1930 he was appointed Professor at Imperial College London in the chair of the late Hugh Longbourne Callendar. In the late 1930s and during the Second World War Thomson specialised in nuclear physics, concentrating on practical military applications. In particular Thomson was the chairman of the crucial MAUD Committee in 1940–1941 that concluded that an atomic bomb was feasible. In later life he continued this work on nuclear energy but also wrote works on aerodynamics and the value of science in society.