born April 13, 1909, Lemberg, Pol., Austria-Hungary
died May 13, 1984, Santa Fe, N.M., U.S.
Polish-born U.S. mathematician and atomic physicist.
He received his doctoral degree in 1933 and was invited by John von Neumann to Princeton University's Institute for Advanced Study in 1936. In 1943 he moved to Los Alamos , N.M., where his early work included development (with von Neumann) of the Monte Carlo method of finding approximate solutions to problems. Later, while working on a fusion bomb, he and Edward Teller developed a two-stage radiation implosion design (the "Teller-Ulam configuration") that could generate an explosion capable of initiating nuclear fusion, a design that led to the creation of the hydrogen bomb .