Yukawa Hideki

Yukawa Hideki (born January 23, 1907, Tokyo, Japan—died September 8, 1981, Kyōto) Japanese physicist and recipient of the 1949 Nobel Prize for Physics for research on the theory of elementary particles.

Yukawa graduated from Kyōto Imperial University (now Kyōto University) in 1929 and became a lecturer there; in 1933 he moved to Ōsaka Imperial University (now Ōsaka University), where he earned his doctorate in 1938. He rejoined Kyōto Imperial University as a professor of theoretical physics (1939–50), held faculty appointments at the Institute for Advanced Study in Princeton, New Jersey (U.S.), and at Columbia University in New York City, and became director of the Research Institute for Fundamental Physics in Kyōto (1953–70).

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In 1935, while a lecturer at Ōsaka Imperial University, Yukawa proposed a new theory of the strong and weak nuclear forces in which he predicted a new type of particle as those forces’ carrier particle. He called it the U-quantum, and it was later known as the meson because its mass was between those of the electron and proton. American physicist Carl Anderson’s discovery in 1937 of a particle among cosmic rays with the mass of the predicted meson suddenly established Yukawa’s fame as the founder of meson theory, which later became an important part of nuclear and high-energy physics. However, by the mid-1940s, it was discovered that Anderson’s new particle, the muon, could not be the predicted carrier particle. The predicted particle, the pion, was not discovered until 1947 by British physicist Cecil Powell, but, despite Yukawa’s successful prediction of the pion’s existence, it also was not the carrier particle of the nuclear forces, and meson theory was supplanted by quantum chromodynamics.

After devoting himself to the development of meson theory, Yukawa started work in 1947 on a more comprehensive theory of elementary particles based on his idea of the so-called nonlocal field.