Walter M. Elsasser

M EM O RIAL TO W ALTER M. ELSÄSSER 183 During this era Walter had the opportunity to explain his insights to Albert Einstein. Ein­ stein had hypothesized that magnetism might be simply a fundamental property of planetary rotation, and this theory spurred P.M.S. Blackett to build extremely sensitive magnetometers (later used so effectively in paleomagnetism) to obtain his famous negative result with rotating spheres. Einstein listened carefully and earnestly to Walter and asked detailed questions in the vein of an electrical engineer, involving motors and wires. Not sure of Einstein’s opinion of the matter, Walter later discreetly probed Einstein’s assistant for an answer. “Oh,” he said, “he didn’t much believe it. He simply could not believe that something so beautiful could have such a com­ plicated explanation.” In recognition of his accomplishments, Walter was elected to the National Academy of Sci­ ences in 1957, received the William Bowie Medal of the American Geophysical Union in 1959, and was elected a Fellow of the American Physical Society. This era was also academically busy for Walter. In 1947 he became associate professor of physics at the University of Pennsylvania, and in 1950 moved as professor to the University of Utah, where he experimented with elec­ tronic computing. In 1956, when the University of California at La Jolla was established, he became one of the founding professors, and in 1960 he became chair of the physics department at the University of New Mexico. Until this time Walter had always been academically labeled a physicist, but his work and interests had become increasingly geophysical. His dynamo theory had become the playground of mathematicians and physicists; there was less and less to hold his imagination. As was his nature, he sensed through developments in paleomagnetism the dawning of a major revolution in earth science, and he was convinced by Harry Hess, the father of that revolution, to go to Prince­ ton as professor of geophysics. Delivered to the very doorstep of seafloor spreading, he was a