John Wheeler supervised more Ph.D. theses than any Princeton physics professor. They included included Richard Feynman, one of the architects of quantum electrodynamics (QED), and Hugh Everett III, inventor of the "universal wave function" and the "relative state" formulation of quantum mechanics, later known as the "many-worlds" interpretation. In the late 1930's, Wheeler worked with Neils Bohr to show that it was U235 that is the fissionable element in Uranium, pointing the path to the atomic bomb. (Wheeler became a great promoter of atomic and later nuclear weapons, encouraging their use against the Soviet Union to destroy communism.) After World War II, Wheeler collaborated with Feynman to argue for the existence of incoming spherical electromagnetic waves (the so-called "advanced" potential). As early as 1905, Albert Einstein argued against outgoing spherical waves (the normal "retarded" potential) and argued for light being large numbers of discrete "light quanta" (later called photons).. Wheeler was a great contributor to many of the new discoveries in astrophysics and cosmology, especially gifted at naming them, e.g., "black hole."