James Watson Cronin (born September 29, 1931) is an American nuclear physicist.

He was born in Chicago, Illinois. Cronin and co-researcher Val Logsdon Fitch were awarded the 1980 Nobel Prize in Physics for a 1964 experiment that proved that certain subatomic reactions do not adhere to fundamental symmetry principles. Specifically, they proved, by examining the decay of K-mesons, that a reaction run in reverse does not merely retrace the path of the original reaction, which showed that the reactions of subatomic particles are not indifferent to time. Thus the phenomenon of CP violation was discovered.

At present, Jim Cronin is Professor Emeritus at the University of Chicago and a spokesperson for the Auger project. Prof. Cronin is a member of the Board of Sponsors of The Bulletin of the Atomic Scientists[1].

Links

• James Watson Cronin
  
• the discovery of violations of fundamental symmetry principles in the decay of neutral K-mesons.
  
• Short biography at the University of Chicago