American theoretical physicist He studied at Harvard University before working with Ernest Rutherford at Cambridge University and Max Born in Germany. While in Europe he met and shared information with Nils Bohr. He returned to the USA in 1929 and over the next few years worked at the University of California. Oppenheimer developed left-wing views and was a strong supporter of the Republicans during the Spanish Civil War. Influenced by the research carried out by Nils Bohr, Lise Meitner, and Leo Szilard, Oppenheimer began to seek a process for the separation of uranium-235 from natural uranium and to determine the critical mass of uranium required to make an atom bomb. In 1943 Oppenheimer was appointed director of the Manhattan Project where he worked with Edward Teller, Enrico Fermi, David Bohm, James Franck, Emilio Segre, Felix Bloch, Rudolf Peierls, James Chadwick, Otto Frisch, Eugene Wigner, Leo Szilard and Klaus Fuchs in developing the atom bombs dropped on Hiroshima and Nagasaki. After the war Oppenheimer served as chairman of the General Advisory Committee of the Atomic Energy Commission. He was now fully aware of the dangers of radioactivity caused by nuclear explosions and in October, 1949, he controversially opposed the development of the hydrogen bomb. Oppenheimer was a victim of McCarthyism and in 1953 he was accused of being closely associated with communists in the 1930s. A security hearing decided he was not guilty of treason but ruled that he should not have access to military secrets. As a result he was removed from the Atomic Energy Commission. In 1963 Oppenheimer was forgiven for his left-wing past when Lyndon B. Johnson awarded him the Enrico Fermi Award.