James Watson Cronin


James Watson Cronin

Photo from the Nobel Foundation archive.

James Watson Cronin

Born: 29 September 1931, Chicago, IL, USA

Died: 25 August 2016, St. Paul, MN, USA

Affiliation at the time of the award: University of Chicago, Chicago, IL, USA

Prize motivation: "for the discovery of violations of fundamental symmetry principles in the decay of neutral K-mesons."

Prize share: 1/2


For a long time, physicists assumed that various symmetries characterized nature. In a kind of "mirror world" where right and left were reversed and matter was replaced by antimatter, the same physical laws would apply, they posited. The left-right symmetry had already been proven violated when, in 1964, James Cronin and Val Fitch discovered that the matter-antimatter symmetry is violated when the neutral K-meson decays. Their experiment also proved that symmetry does not apply during time reversal: reactions going backward in time are not identical to those going forward.

To cite this section
MLA style: James Cronin – Facts. NobelPrize.org. Nobel Media AB 2018. Fri. 19 Oct 2018. <https://www.nobelprize.org/prizes/physics/1980/cronin/facts/>

Back to top Back To Top Takes users back to the top of the page

Explore prizes and laureates

Look for popular awards and laureates in different fields, and discover the history of the Nobel Prize.