Walter Kohn. 9 March 1923—19 April 2016

Walter Kohn, a giant of theoretical physics, died at his home in Santa Barbara, California, on 19 April 2016, at the age of 93. Walter's life epitomized both the hardships and the wondrous achievements of physicists in the twentieth century. He escaped from Nazi-occupied Austria on one of the last children's rescue trains (the Kindertransport ) and during World War II spent 18 months confined in internment camps in England and Canada. He learned only after the War that both of his parents had perished in Auschwitz. After earning physics degrees at the University of Toronto and at Harvard University, he rapidly emerged as a leader in bringing quantum theory to bear on problems in the electron theory of solids. Walter's devotion to basic scientific principles led to the density functional theory of electrons in solids and in chemical molecules in the 1960s. Thirty years later, once the vast importance of this theory had become clear, he was awarded a Nobel Prize in Chemistry for this discovery. In his later years Walter turned much of his attention to institution building and public affairs. He was the founding director of the Institute for Theoretical Physics at the University of California, Santa Barbara. He was deeply committed to the control of nuclear weapons, the development of renewable clean energy and the free exchange of knowledge among scientists throughout the world.