The Nobel Prize in Physics 1949
Born: 23 January 1907, Tokyo, Japan
Died: 8 September 1981, Kyoto, Japan
Affiliation at the time of the award: Kyoto Imperial University, Kyoto, Japan, Columbia University, New York, NY, USA
Prize motivation: "for his prediction of the existence of mesons on the basis of theoretical work on nuclear forces"
Field: quantum mechanics
Atomic nuclei consist of protons and neutrons, kept together by a strong force. Hideki Yukawa assumed that the force is carried by particles and further, that there is a relation between the range of the force and the mass of the force carrying particle. Yukawa predicted in 1934 that the particle should have a mass of about 200 times that of the electron. He called the particle a meson. In later experiments, the existence of mesons was verified.