“This is an unreal place,” [Abraham] Pais wrote in his diary in February 1948. “Bohr comes into my office to talk, I look out the window and see Einstein walking home with his assistant. Two offices away sits Dirac. Downstairs sits Oppenheimer....” It [Institute of Advanced Study, Princeton] was a concentration of scientific talent like no other in the world... except, of course, Los Alamos.