Shinichirō Tomonaga
| Shin'ichirō Tomonaga | |
|---|---|
 |
|
| Born |
March 31, 1906 Tokyo, Japan |
| Died | July 8, 1979 (aged 73) Tokyo, Japan |
| Fields | Theoretical physics |
| Institutions |
Institute for Advanced Study Tokyo University of Education RIKEN |
| Alma mater | Kyoto Imperial University |
| Known for | Quantum electrodynamics |
| Notable awards | Asahi Prize (1946) Lomonosov Gold Medal (1964) Nobel Prize in Physics (1965) |
Shin'ichirō Tomonaga(朝永 振一郎 Tomonaga Shin'ichirō, March 31, 1906 – July 8, 1979), usually cited as Sin-Itiro Tomonaga in English, was a Japanese physicist, influential in the development of quantum electrodynamics, work for which he was jointly awarded the Nobel Prize in Physics in 1965 along with Richard Feynman and Julian Schwinger.
Tomonaga was born in Tokyo in 1906. He was the second child and eldest son of a Japanese philosopher, Tomonaga Sanjūrō. He entered the Kyoto Imperial University in 1926. Hideki Yukawa, also a Nobel Prize winner, was one of his classmates during undergraduate school. During graduate school at the same university, he worked as an assistant in the university for three years. In 1931, after graduate school, he joined Nishina's group in Riken. In 1937, while working at Leipzig University (Leipzig), he collaborated with the research group of Werner Heisenberg. Two years later, he returned to Japan due to the outbreak of the Second World War, but finished his doctoral degree on the study of nuclear materials with his thesis on work he had done while in Leipzig.
In Japan, he was appointed to a professorship in the Tokyo University of Education (a forerunner of Tsukuba University). During the war he studied the magnetron, meson theory, and his super-many-time theory. In 1948, he and his students re-examined a 1939 paper by Sidney Dancoff that attempted, but failed, to show that the infinite quantities that arise in QED can be canceled with each other. Tomonaga applied his super-many-time theory and a relativistic method based on the non-relativistic method of Wolfgang Pauli and Fierz to greatly speed up and clarify the calculations. Then he and his students found that Dancoff had overlooked one term in the perturbation series. With this term, the theory gave finite results; thus Tomonaga discovered the renormalization method independently of Julian Schwinger and calculated physical quantities such as the Lamb shift at the same time.
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