Val Fitch

Facts

Val Logsdon Fitch

Photo from the Nobel Foundation archive.

Val Logsdon Fitch
Nobel Prize in Physics 1980

Born: 10 March 1923, Merriman, NE, USA

Died: 5 February 2015, Princeton, NJ, USA

Affiliation at the time of the award: Princeton University, Princeton, NJ, USA

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

Prize share: 1/2

Work

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, Val Fitch and James Cronin 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: Val Fitch – Facts. NobelPrize.org. Nobel Prize Outreach 2026. Thu. 13 Aug 2026. <https://www.nobelprize.org/prizes/physics/1980/fitch/facts/>

Explore prizes and laureates

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