Julian Schwinger
From Wikipedia, the free encyclopedia
Julian Schwinger  |
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| Born | February 12, 1918 New York City, U.S. |
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| Died | July 16, 1994 (aged 76) Los Angeles, U.S. |
| Residence | U.S. |
| Nationality | American |
| Fields | Physicist |
| Institutions | University of California, Berkeley Purdue University Massachusetts Institute of Technology Harvard University University of California at Los Angeles |
| Alma mater | City College of New York Columbia University |
| Doctoral advisor | Isidor Isaac Rabi |
| Doctoral students | Roy Glauber Ben R. Mottelson |
| Known for | Quantum electrodynamics |
| Notable awards | Nobel Prize in Physics (1965) |
Julian Seymour 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 jointly awarded the Nobel Prize in Physics in 1965 for his work on quantum electrodynamics (QED), along with Richard Feynman and Shinichiro Tomonaga.
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[edit] Life and career
Schwinger was born in New York City where he attended Townsend Harris High School and then the City College of New York as an undergraduate before transferring to Columbia University, where he received his B.A. in 1936 and his Ph.D. (overseen by I.I. Rabi) in 1939. He worked at the University of California, Berkeley (under J. Robert Oppenheimer) 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. He tried applying his knowledge as a Nuclear Physicist to electromagnetic engineering problems, and arrived at results on nuclear scattering. Consequently, 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. 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, which was experimentally verified in recent years.
Having supervised more than seventy doctoral dissertations, Schwinger is known as one of the most prolific graduate advisors in physics. Four of his students won Nobel prizes: Roy Glauber, Benjamin Roy Mottelson, Sheldon Glashow and Walter Kohn (in chemistry).
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 1972 for a position at the University of California, Los Angeles where he continued his work on source theory, until his death.
After 1989 Schwinger took a keen interest in the research of low-energy nuclear fusion reactions (AKA cold fusion). He wrote eight theory papers about it. He resigned from the American Physical Society after their refusal to publish his papers. He felt that cold fusion research was being suppressed and academic freedom violated. He wrote: "The pressure for conformity is enormous. I have experienced it in editors’ rejection of submitted papers, based on venomous criticism of anonymous referees. The replacement of impartial reviewing by censorship will be the death of science."
Schwinger is buried at Mount Auburn Cemetery; 
is engraved above his name on his tombstone.These symbols refer to his calculation of the correction ("anomalous") to the magnetic moment of the electron.
[edit] Schwinger and Feynman
As a famous physicist, Schwinger was often compared to another legendary physicist of his generation, Richard Feynman. Schwinger was more mathematically inclined and heavily favoured mathematical rigour in his way of doing physics, especially in the field of Quantum Field Theory. By contrast, Feynman was more intuitive and this showed in his Feynman diagram approach to QFT. Schwinger commented on Feynman digrams in the following way,
| “ | Like the silicon chips of more recent years, the Feynman diagram was bringing computation to the masses. [1] | ” |
Schwinger disliked Feynman diagrams to the point of banning them altogether in his class, although he understood them perfectly and was observed to use them in private. Despite sharing the Nobel Prize, Schwinger and Feynman had a different approach to quantum electrodynamics,although they respected each other's work. On Feynman's death, Schwinger described him as
| “ | An honest man, the outstanding intuitionist of our age, and a prime example of what may lie in store for anyone who dares to follow the beat of a different drum.[2] | ” |
[edit] See also
- Schwinger model
- Schwinger-Dyson equations
- Schwinger's variational principle
- Rarita-Schwinger action
- Lippmann-Schwinger equation
- Schwinger parametrization
[edit] Further reading
- Mehra, Jagdish and Milton, Kimball A. Climbing the Mountain: the scientific biography of Julian Schwinger, Oxford University Press, 2000.
- Milton, Kimball (2006-10-9). Julian Schwinger: Nuclear Physics, the Radiation Laboratory, Renormalized QED, Source Theory, and Beyond. arXiv.; revised version published as "Julian Schwinger: From Nuclear Physics and Quantum Electrodynamics to Source Theory and Beyond," Physics in Perspective, 9, 70-114 (2007)
- Schweber, Sylvan S., QED and the men who made it : Dyson, Feynman, Schwinger, and Tomonaga. Princeton Univ. Press, 1994.
- Ng, Y. Jack, Ed., Julian Schwinger; the Physicist, the Teacher, and the Man ,World Scientific, Singapore , 1996 ISBN 9810225318
[edit] External links
- Julian Schwinger
- Nobel Museum Biography
- fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles
[edit] References
- ^ J. Schwinger, "Quantum Electrodynamics-An Individual View," J. Physique 43, Colloque C-8, Supplement au no. 12, 409 (1982) and "Renormalization Theory of Quantum Electrodynamics: An Individual View," in The Birth of Particle Physics, Cambridge University Press, 1983, p. 329
- ^ http://amasci.com/feynman.html; "A Path to Quantum Electrodynamics," Physics Today, February 1989
| Persondata | |
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| NAME | Schwinger, Julian |
| ALTERNATIVE NAMES | |
| SHORT DESCRIPTION | Physicist |
| DATE OF BIRTH | February 12, 1918 |
| PLACE OF BIRTH | New York City, U.S. |
| DATE OF DEATH | July 16, 1994 |
| PLACE OF DEATH | Los Angeles, U.S. |
