Julian Schwinger (February 12, 1918 -- July 16, 1994) was an American theoretical physicist. He formulated the theory of renormalization and posited a phenomenon of electron-positron pairs known as the Schwinger effect. He was awarded the Nobel Prize in Physics in 1965 for his work on quantum electrodynamics (QED).
Schwinger was born in New York City, attended the City College of New York as an undergraduate, and received his doctorate from Columbia University in 1939 where he studied under I.I. Rabi. He worked at the University of California, Berkeley and was later appointed to a position at Purdue University.
During World War II Schwinger worked at the Radiation Laboratory at MIT, providing theoretical support for the development of radar. During this time, Schwinger began to apply his understanding of radiation to quantum physics.
After the war, Schwinger left Purdue for Harvard University, where he taught from 1945 to 1974. He married in 1947. During this time, he developed the concept of renormalization, which explained the Lamb shift in an electron's magnetic field. He also realized, in his study of particle physics, that neutrinos would come in multiple varieties, associated with leptons like the electron and muon.
In his later career, displeased with the complexity of other explanations of particle physics experiments, Schwinger developed source theory, which treats gravitons, photons, and other particles uniformly.
Schwinger left Harvard in 1974 for a position the University of California, Los Angeles where he continued his work on source theory. Here, he established a legacy of excellent lecturing and mentoring skills; three of his students themselves went on to win Nobel Prizes.