J(ulius) Robert Oppenheimer

Oppenheimer, J(ulius) Robert (1904–67), U.S. physicist who headed the Manhattan Project (1942–45) which developed the atomic bomb. He fought against the construction of the hydrogen bomb but was overruled by President Harry S. Truman in 1949. His main aim was the peaceful use of nuclear power, but because of his left-wing friendships, he was unable to pursue his researches in this direction after being labeled a security risk in 1954. He also worked out much of the theory of black holes in the universe.

See also: Manhattan Project.