J. Robert Oppenheimer

Julius Robert Oppenheimer was born on 22 April 1904 in New York City into a wealthy family of German-Jewish background. He showed wide intellectual interests from an early age and studied chemistry at Harvard University, completing his undergraduate degree in three years. He then traveled to Europe, studying first at the Cavendish Laboratory in Cambridge and then at the University of Göttingen under Max Born, where he received his doctorate in theoretical physics in 1927.

Returning to the United States, Oppenheimer held joint appointments at the University of California, Berkeley, and the California Institute of Technology. During the late 1920s and 1930s, he made contributions to quantum mechanics, including work on the Born-Oppenheimer approximation, which separates the motion of electrons and nuclei in molecular calculations. He and his students also worked on theoretical aspects of cosmic rays, nuclear physics, and the behaviour of extremely dense stellar objects, including what are now understood as black holes and neutron stars.

In 1942, Oppenheimer was appointed scientific director of the Manhattan Project, the United States government programme to develop nuclear weapons during the Second World War. He directed the Los Alamos Laboratory in New Mexico, where a concentrated group of scientists from several countries worked on the design and construction of fission weapons. The first test of a nuclear device took place in New Mexico in July 1945.

After the war, Oppenheimer became chairman of the General Advisory Committee of the Atomic Energy Commission and director of the Institute for Advanced Study in Princeton. He engaged in public debates about the control and development of nuclear weapons and expressed reservations about the development of thermonuclear weapons.

In 1954, during the McCarthy era, Oppenheimer's security clearance was revoked following hearings in which his past political associations and opposition to the hydrogen bomb programme were examined. He was not charged with any crime but was effectively removed from government advisory roles. He continued as director of the Institute for Advanced Study until 1966. He died on 18 February 1967 in Princeton, New Jersey. His security clearance was posthumously restored in 2022 by the United States Department of Energy.