Schwinger, Julian Seymour

▪ 1995

      U.S. physicist (b. Feb. 12, 1918, New York, N.Y.—d. July 16, 1994, Los Angeles, Calif.), was a brilliant theoretician whose studies helped define the basic principles of quantum electrodynamics, a theoretical description of the interaction of electrically charged particles with electromagnetic radiation; he won the 1965 Nobel Prize for Physics (with Richard P. Feynman of the U.S. and Tomonaga Shin'ichiro of Japan) for this important work. His mathematical formulations provided a vital link between quantum mechanics and Albert Einstein's special theory of relativity. A prodigy, Schwinger received (1939) a Ph.D. from Columbia University, New York City, at the age of 21 and began conducting research in the newly emerging field of nuclear physics under J. Robert Oppenheimer at the University of California at Berkeley. During World War II he helped develop radar at the Radiation Laboratory of the Massachusetts Institute of Technology. In 1945 he joined the faculty of Harvard University, where he began his work on quantum electrodynamics and became the first to calculate the anomalous magnetic property of the electron. His superb teaching methods were distinguished by scintillating lectures, and his mentorship of students resulted in dozens of them earning their Ph.D.'s under his guidance. Three of his pupils also later won Nobel Prizes. From 1972 to 1980 he served as professor of physics at the University of California at Los Angeles, and from 1980 until his death he was university professor there. Among his other honours were the first Albert Einstein Prize in 1951 (with Kurt Gödel) and the National Medal of Science in 1964.

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▪ American physicist

born Feb. 12, 1918, New York, N.Y., U.S.

died July 16, 1994, Los Angeles, Calif.

      American physicist and joint winner, with Richard P. Feynman (Feynman, Richard P.) and Tomonaga Shin'ichirō, of the Nobel Prize for Physics in 1965 for introducing new ideas and methods into quantum electrodynamics.

      Schwinger was a child prodigy, publishing his first physics paper at age 16. He earned a bachelor's degree (1937) and a doctorate (1939) from Columbia University in New York City, before engaging in postdoctoral studies at the University of California at Berkeley with physicist J. Robert Oppenheimer (Oppenheimer, J. Robert). Schwinger left Berkeley in the summer of 1941 to accept an instructorship at Purdue University, West Lafayette, Ind., and in 1943 he joined the Radiation Laboratory at the Massachusetts Institute of Technology, where many scientists had been assembled to help with wartime research on radar. In the fall of 1945 Schwinger accepted an appointment at Harvard University and in 1947 became one of the youngest full professors in the school's history. From 1972 until his death, Schwinger was a professor in the physics department at the University of California at Los Angeles.

      Schwinger was one of the participants at the meeting held in June 1947 on Shelter Island, Long Island, N.Y., at which reliable experimental data were presented that contradicted the predictions of the English theoretical physicist P.A.M. Dirac (Dirac, P.A.M.)'s relativistic quantum theory of the electron. In particular, experimental data contradicted Dirac's prediction that certain hydrogen electron stationary states were degenerate (i.e., had the same energy as certain other states) as well as Dirac's prediction for the value of the magnetic moment of the electron. Schwinger made a quantum electrodynamical calculation that made use of the notions of mass and charge renormalization, which brought agreement between theory and experimental data. This was a crucial breakthrough that initiated a new era in quantum field theory. Richard Feynman and Tomonaga Shin'ichirō independently had carried out similar calculations, and in 1965 the three of them shared the Nobel Prize. Their work created a new and very successful quantum mechanical description of the interaction between electrically charged entities and the electromagnetic field that conformed with the principles of Albert Einstein (Einstein, Albert)'s special theory of relativity.

      Schwinger's work extended to almost every frontier of modern theoretical physics. He had a profound influence on physics both directly and through being the academic adviser for more than 70 doctoral students and more than 20 postdoctoral fellows, many of whom became the outstanding theorists of their generation.

Silvan Schweber

Additional Reading

Kimball A. Milton, A Quantum Legacy: Seminal Papers of Julian Schwinger (2000); Y. Jack Ng (ed.), Julian Schwinger: The Physicist, the Teacher, and the Man (1996); S. Deser and R.J. Finkelstein (eds.), Themes in Contemporary Physics II: Essays in Honour of Julian Schwinger's 70th Birthday (1989); Jagdish Mehra and Kimball A. Milton, Climbing the Mountain: The Scientific Biography of Julian Schwinger (2000).

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