Elsasser, Walter Maurice (1904–1991)

German-born US geophysicist. He pioneered analysis of the Earth's former magnetic fields, which are frozen in rocks. His research in the 1940s yielded the dynamo model of the Earth's magnetic field. The field is explained in terms of the activity of electric currents flowing in the Earth's fluid metallic outer core. The theory premises that these currents are magnified through mechanical motions, rather as currents are sustained in power-station generators.

Born in Mannheim and educated at Göttingen, Elsasser left in 1933 following Hitler's rise to power, and spent three years in Paris working on the theory of atomic nuclei. After settling in 1936 in the USA and joining the staff of the California Institute of Technology, he specialized in geophysics. Elsasser became a professor at the University of Pennsylvania 1947; in 1962 he was made professor of geophysics at Princeton.