Tomonaga, Sin-Itiro (or Shin'ichiro) (1906–1979)

Japanese theoretical physicist who was awarded the Nobel Prize for Physics in 1965 for developing the theory of quantum electrodynamics (QED). Tomonaga, Richard Feynman, and Julian Schwinger independently developed methods for calculating the interaction between electrons, positrons, and photons. The three approaches were essentially the same and QED remains one of the most accurate physical theories known.

Tomonaga developed his quantum theory of the interaction between high-energy sub-atomic particles 1941–43. His central concept was that two sub-atomic particles interact by exchanging a third particle, like footballers throwing the ball to one another. Tomonaga was able to use this idea to produce a theory that was consistent with Einstein's theory of special relativity. In the USA, Feynman and Schwinger developed the same theory but the three were unaware of each other's work. World War II prevented news of Tomonaga's work from circulating outside Japan until 1947. All three had arrived independently at the same theory.

Tomonaga was born in Tokyo, Japan, and graduated from Kyoto University in 1929. He became professor of physics at the University of Tokyo in 1941 and president of the university in 1956.