J. Robert Oppenheimer (April 22, 1904 – February 18, 1967) was an American theoretical physicist, best known for his role as the director of the Manhattan Project, the World War II effort to develop the first nuclear weapons, at the secret Los Alamos laboratory in New Mexico. Known as "the father of the atomic bomb," Oppenheimer was shocked by the weapon's killing power after it was used to destroy the Japanese cities of Hiroshima and Nagasaki. Quoting from the Bhagavad Gita, he said "If the radiance of a thousand suns were to burst at once into the sky, that would be like the splendor of the mighty one. Now I am become Death, the destroyer of worlds."
After the war, Oppenheimer was a chief advisor to the newly created United States Atomic Energy Commission and used that position to lobby for international control of atomic energy and to avert the nuclear arms race with the Soviet Union. After invoking the ire of many politicians and scientists with his outspoken political opinions during the Red Scare, he had his security clearance revoked in a much-publicized and politicized hearing in 1954. Though stripped of his direct political influence, Oppenheimer continued to lecture, write, and work in physics. A decade later, President John F. Kennedy awarded him the Enrico Fermi Award as a gesture of political rehabilitation.
As a scientist, Oppenheimer is remembered most for being the chief founder of the American school of theoretical physics while at the University of California, Berkeley. At the Institute for Advanced Study, he would hold Einstein's old position of senior professor of theoretical physics. Oppenheimer's notable achievements in physics include the Born-Oppenheimer approximation, as well as work on electron-positron theory, the Oppenheimer-Phillips process, quantum tunneling, relativistic quantum mechanics, quantum field theory, black holes, and cosmic rays.