- Person
- Julian Schwinger
- Lived
- 1918–1994
- Field
- Theoretical physics
- From
- American
The story
Julian Schwinger, born in 1918 to a Jewish family in Manhattan, was one of the most gifted theoretical physicists of his generation. He published his first paper as a teenager and earned his doctorate at Columbia at twenty-one. When the United States entered the Second World War, most leading physicists went to Los Alamos to build the atomic bomb. Schwinger joined the Radiation Laboratory at the Massachusetts Institute of Technology in 1943 to work on radar instead.
His biographer and former student Kimball Milton writes that the reason Schwinger most often gave later in life was moral repugnance at the destructive power of the bomb, while radar was a primarily defensive technology that had already saved Britain. He also found the radar problems more interesting, and the laboratory let him keep his habit of working through the night.
Schwinger quickly became the Radiation Laboratory’s theoretical leader. Radar depends on guiding high-frequency microwaves through metal pipes called waveguides and complicated circuits, and Maxwell’s equations, though well known, were hard to apply to them. Schwinger developed powerful variational methods to solve these problems and, crucially, expressed his results in terms engineers could use, such as impedance and admittance. His lectures were later published as a book on electromagnetic radiation, waveguides and accelerators.
As the war ended he turned to the new particle accelerators and worked out in detail the theory of synchrotron radiation, the intense light emitted by electrons travelling in curved paths at nearly the speed of light, at a time when many expected it to be negligible. He published the full theory in 1949, two years after the radiation was first seen at a General Electric synchrotron in Schenectady, New York. Since the 1980s, dedicated synchrotron light sources have been built around the world to produce this radiation for research, including the study of protein structures by structural biologists. Schwinger went on to help create quantum electrodynamics, sharing the 1965 Nobel Prize in Physics with Richard Feynman and Sin-Itiro Tomonaga.
Why it matters
Schwinger’s wartime theory helped make radar work, and his synchrotron radiation theory describes the light that synchrotron sources now produce for research on proteins and materials.
About Julian Schwinger
New York prodigy who helped create quantum electrodynamics, the most precisely tested theory in science, led wartime radar theory and explained synchrotron light. Nobel Prize 1965.
Sources
- Julian Schwinger (1918–1994), by K. A. Milton arXiv
- Julian Schwinger, Biographical NobelPrize.org
- Julian Schwinger Wikipedia
- Synchrotron radiation Wikipedia
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