Schwinger, Julian Seymour (1918-1994) was an American physicist. He won the 1965 Nobel Prize in physics for basic work in quantum electrodynamics. Quantum electrodynamics is the study of the interaction between electrons and electromagnetic radiation. The improved theory of quantum electrodynamics developed by Schwinger enables scientists to predict accurately the effects of electrically charged particles on each other in a radiation field. Schwinger shared the prize with the American physicist Richard Phillips Feynman and the Japanese physicist Sin-Itiro Tomonaga, who independently did similar work in quantum electrodynamics.

Schwinger was born in New York City. His parents were Benjamin Schwinger, a designer and manufacturer of dresses, and Belle Rosenfeld Schwinger. Julian Schwinger had one older brother.

Schwinger took an interest in physics during high school. He studied the work of the British theoretical physicist Paul Adrien Maurice Dirac, who became noted in the late 1920's for his mathematical equation describing the behavior of the electron. Dirac was an important contributor to quantum mechanics, a field of physics that describes the structure of the atom and the motion of atomic particles. It also explains how atoms absorb and give off light, and it clarifies the nature of light.

After graduating from high school at the age of 14, Schwinger attended City College of New York and then transferred to Columbia University to study nuclear physics. He wrote his first paper on quantum electrodynamics when he was 16.

Schwinger earned a bachelor's degree in physics from Columbia in 1937, at the age of 17. From 1936 to 1938, he did graduate work at the University of Wisconsin. He then returned to Columbia, where he received his doctorate in physics in 1939.

Schwinger won a National Research Council fellowship for further study at the University of California at Berkeley from 1939 to 1940. There he worked with the noted American physicist J. Robert Oppenheimer. Schwinger stayed on as a research associate at Berkeley from 1940 to 1941. With Oppenheimer, he wrote scientific papers on nuclear theory and about mesons, certain kinds of unstable atomic particles.

In 1941, Schwinger joined the faculty of Purdue University in Indiana as an instructor. He was promoted to assistant professor in 1942.

In the summer of 1943, during World War II (1939–1945), Schwinger left Purdue and went to work on the development of the atomic bomb at the University of Chicago's metallurgical laboratory. Later that year, he transferred to the radiation laboratory at the Massachusetts Institute of Technology (MIT), where he worked on radar systems and did research on microwaves.

In 1945, after the war ended, Schwinger became an associate professor at Harvard University. He was promoted to full professor in 1947. With his colleague Bernard Lippmann, Schwinger formulated the Lippmann-Schwinger equations to explain the principles of electron scattering. Schwinger also became a popular lecturer.

Schwinger did the work for which he won the Nobel Prize in the late 1940's. His explanations of his theory of quantum electrodynamics were published in the scientific journal Physical Review in 1948 and 1949.

Schwinger was elected to the National Academy of Sciences in 1949. He also was honored with the Charles L. Mayer Nature of Light Award in 1948, Columbia's University Medal and the first Albert Einstein Prize in 1951, and the National Medal of Science in 1964.

Throughout his career, Schwinger wrote nearly 200 scientific papers and a number of books. He explained his work in quantum electrodynamics in the scientific texts Differential Equations of Quantum Field Theory (1956), The Theory of the Fundamental Interactions (1957), and Quantum Kinematics and Dynamics (1970). Schwinger edited a collection of scientific papers written by himself and others in his field in the volume Selected Papers on Quantum Electrodynamics (1958). Notes from Schwinger's lectures on microwaves were collected in the book Discontinuities in Wave Guides (with David Saxon, 1968). His three-volume work Particles, Sources, and Fields was published in 1970, 1973, and 1983.

Schwinger remained at Harvard until 1972. From 1966 to 1972, he held the title Higgins professor of physics. He was a professor at the University of California at Los Angeles from 1972 until his death. He wrote Einstein's Legacy: The Unity of Space and Time in 1986. This book was based on his television program “Understanding Space and Time,” which was produced for the British Broadcasting Corporation (BBC).