Oppenheimer was born into a wealthy family in New York City on April 22, 1904. He attended Harvard, Cambridge, and Göttingen universities. He worked under Ernest Rutherford at Cambridge and received his doctorate in physics in 1927 after working with Max Born at Göttingen. In 1929, he accepted concurrent appointments to teach physics at the University of California at Berkeley and at the California Institute of Technology.

Oppenheimer rapidly made a reputation as a brilliant theoretician as well as an effective and popular teacher. During the 1930s, he produced a series of important papers dealing with such topics as the particle theories of Werner Heisenberg and Paul Adrien Maurice Dirac, the mistaken concept of nuclear electrons, neutron capture by nuclei, the nature of cosmic radiation, and meson production.

It is for his role in the Manhattan Project, however, that Oppenheimer is perhaps best known. A 1939 letter signed by...