Education, Columbia; Depression; Cambridge University, England; research with I.I. Rabi, Enrico Fermi; National Defense Research Committee radiation laboratory; Massuchusetts Institute of Technology; England, 1941; security problems; radar; Manhattan Project, 1943; Los Alamos; discussions on use of bomb and possible targets; Trinity test; Tinian; estimates of damage, Hiroshima; Brookhaven; Harvard; Congressional investigations; Harold Velde and Joseph McCarthy hearings; area rule; appearance on "Meet the Press," subsequent meeting with Senator McCarthy; contempt citations; Kamen trial; Robert Oppenheimer case; Gray Board; science adviser, North Atlantic Treaty Organization; impressions of General Leslie Groves, Admiral Lewis L. Strauss, Edward Teller.