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Sin-Itiro Tomonaga: 1906 - 1979, a Briefing
by Jeanette Cain
Born in Tokyo, Japan on March 31, 1906, later a physicist, the pride of the Japanese people. He was graduated from Kyoto Imperial University, but after graduation studied quantum mechanics at the Institute of Physical and Chemical Research. After the war, Tomonaga taught elementary particle physics and studied quantum electrodynamics. His focus was the super-many-time theory and the renormalization theory. For his contributions to the study of quantum mechanics, he was awarded a Nobel Prize in 1965.
Biographical Data
Tomonaga was the eldest son of Sanjuro Tomonaga and Hide Tomonaga. In 1913 his family moved to Kyoto when his father was appointed professor of philosophy at Kyoto Imperial University. He was a graduate of the Third Higher School in Kyoto, which was a renowned senior high school.
Tomonaga completed work for a bachelor's degree in physics at Kyoto Imperial University in 1929. He did graduate work for three years and then appointed research associate at the Institute of Physical and Chemical Research, Tokyo, where he started to work in a newly developed frontier of theoretical physics quantum electrodynamics - under the guidance of Dr. Nishina. His paper on the photoelectric pair creation is well known.
He was appointed an assistant at a research center headed by Yoshio Nishino in 1931. At that time neutrons and positrons, cosmic rays and nuclear power had only recently been discovered. From 1937 to 1939, Tomonaga studied in Germany at Leipzig University in nuclear physics. This is the time when he published the paper "Innere Reibung und Wärmeleitfähigkeit der Kernmaterie". It was chosen as the thesis for Rigakuhakushi (Doctor of Science) at Tokyo Imperial University in December 1939.
Returning to Japan, Tomonaga married Ryoko Sekiguchi in 1940. Sekiguchi was the daughter of Dr. K. Sekiguchi, former Director of the Tokyo Metropolitan Observatory. Tomonaga had two sons and one daughter. He also continued his study of relativity formulas for the quantum field theory. At this time he began to direct his attention to the meson theory. Tomonaga developed the intermediate coupling theory, which clarified the structure of the meson cloud around the nucleon. He became a faculty member of Tokyo Bunrika University as Professor of Physics in 1941. It was in 1942 when he first proposed the covariant formulation of the quantum field theory. He finished work on his renormalization and supertime theories in 1947, gaining him global fame.
In 1941, he became professor of physics at Bunrika University, now known as Tokyo University of Education. This was also the year he began investigating the problems of quantum electrodynamics. Although World War II kept him from collaborating with Western scientists, he did complete and publish his research in 1943. During World War II, Dr. Tomonaga focused on developing a theory of microwave systems. He found a solution for the motion of electrons in the magnetron and developed a unified theory of wave-guides and cavity resonators systems. At war's end, his work was recognized by the western world. He was the first to summarize and extend the coupling theory and to apply the covariant field theory to physical systems. This gave him the next step for developing the renormalization theory with covariant formalism in his right hand. Before the Lamb-Rutherford experiment, by the use of a model calculation, Tomonaga realized that the divergence difficulty in quantum electrodynamics could be overcome, in one way or another, by handling infinite mass and charge due to field reactions. With this, Tomonaga held experimental support in his left hand. It was about this time that Feynman and Schwinger published results from their research. It was found that all three basically achieved the same result, but from different approaches. Their changes made the theory of quantum electrodynamics consistent with the special theory of relativity resolving the inconsistencies of the old theory without making drastic changes.
In 1949, Dr. Tomonaga went to the Institute for Advanced Study, Princeton. Here he studied the investigation of a one-dimensional fermions system. He succeeded in clarifying the nature of collective oscillations of a quantum-mechanical many-body system and opened a new frontier of theoretical physics, modern many-body problem. He published scientific journals on these same subjects and his book, "Quantum Mechanics", was published in 1949.
In 1955, he published an elementary theory of quantum mechanical collective motions and became a leader in establishing the Institute for Nuclear Study at the University of Tokyo. From 1956 to 1962 he served as President of the Tokyo University of Education. From 1963 until his death in 1979, he served as President of the Science Council of Japan and Director of the Institute for Optical Research.
During the latter years of his life, Tomonaga was an active campaigner against spreading of nuclear weapons and for resources to be spent on the peaceful use of nuclear energy. He had almost finished his book What is Physics? before dying in 1979. Dr. Tomonaga's awards, honors and memberships included: Japan Academy Prize-1948; Order of Culture-1952; Lomonosov Medal, U.S.S.R.-1964; member of the Japan Academy; Deutsche Akademie der Naturforscher "Leopoldina"; Royal Swedish Academy of Science; foreign associate of the National Academy of Science, USA; and member of the Bayerische Akademie der Wissenschaften.
Helpful sites:
Nobel Lecture
1965 Nobel Lecture by Sin-Itiro Tomonaga. Personal Recollections on the Development of Quantum Electrodynamics.
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