Oppenheimer, J(ulius) Robert (1904–1967)

US physicist. As director of the Los Alamos Science Laboratory 1943–45, he was in charge of the development of the atom bomb (the Manhattan Project). He objected to the development of the hydrogen bomb, and was alleged to be a security risk in 1953 by the US Atomic Energy Commission (AEC).

Investigating the equations describing the energy states of the atom, Oppenheimer showed in 1930 that a positively charged particle with the mass of an electron could exist. This particle was detected in 1932 and called the positron.

Oppenheimer was the son of a German immigrant. In 1963 the AEC, under G T Seaborg, granted him the Fermi award in physics.

Oppenheimer was born in New York and studied at Harvard, going on to postgraduate work with physicists Ernest Rutherford and J J Thomson at Cambridge, England, and Max Born at Göttingen, Germany. Between 1929 and 1942 he was on the staff of both the University of California, Berkeley, and the California Institute of Technology. After World War II he returned briefly to California and then in 1947 was made director of the Institute of Advanced Study at Princeton University. Oppenheimer also served as chair of the General Advisory Committee to the AEC 1946–52. During World War II he reported to the Federal Bureau of Investigation friends and acquaintances who he thought might be communist agents; physicist David Bohm was one such.