J. Robert Oppenheimer was an American theoretical physicist best known for his role as the scientific director of the Manhattan Project, the World War II initiative that developed the first nuclear weapons. Born on April 22, 1904, in New York City, he made significant contributions to quantum mechanics and nuclear physics. After the war, Oppenheimer became a prominent advocate for the peaceful use of atomic energy. He served as the chairman of the Atomic Energy Commission and was involved in debates about nuclear policy during the early Cold War. He passed away on February 18, 1967.