Cronin, James Watson (1931– )

US physicist. He shared the Nobel Prize for Physics in 1980 with Val Fitch for their work in particle physics. They showed for the first time that left–right asymmetry is not always preserved when some particles are changed in state from matter to antimatter.

The discovery for which Fitch and Cronin received the Nobel Prize was first published in 1964, and at that time was regarded as a bombshell in the field of particle physics. Their findings have had impact on an outstanding controversy about the symmetry of nature.

Cronin was born in Chicago, Illinois, and educated at the Southern Methodist University and the University of Chicago. He was at Princeton 1958–71, as professor from 1965, and became professor at the University of Chicago in 1971.