Photo from the Nobel Foundation archive.
Born: 31 March 1906, Kyoto, Japan
Died: 8 July 1979, Tokyo, Japan
Affiliation at the time of the award: Tokyo University of Education, Tokyo, Japan
Prize motivation: "for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles."
Prize share: 1/3
Following the establishment of the theory of relativity and quantum mechanics, an initial relativistic theory was formulated for the interaction between charged particles and electromagnetic fields. The theory had to be reformulated, however, partly due to the observation of the Lamb shift in 1947, in which the supposed single energy level within a hydrogen atom was instead proven to be two similar levels. Sin-Itiro Tomonga solved this problem in 1948 through a "renormalization" and thereby contributed to a new quantum electrodynamics.