Val Logsdon Fitch (March 10, 1923 – February 5, 2015) was an American
nuclear physicist who, with co-researcher
James Cronin, was awarded the 1980
Nobel Prize in Physics for a 1964 experiment using the
Alternating Gradient Synchrotron at
Brookhaven National Laboratory 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 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. This demolished the faith that physicists had that natural laws were governed by symmetry.