Niels Bohr, Danish physicist, winner of the Nobel Prize in physics, and a member of the team of scientists who worked on the Manhattan Project, lectures graduate students in this undated photograph, according to archivists. Bohr began a 20-year association with the Institute for Advanced Study when he was a guest for the spring semester in 1939. During his time at the institute, Bohr and the late Princeton physics professor John Wheeler developed a theory of nuclear fission that formed the basis for work in atomic energy. Bohr died in 1962.