James Cronin, Nobel Laureate, 1980.

I met Cronin many times when I was visiting Princeton in 1961 and 62-63. His discovery (with V. Fitch) that time-reversal is not an exact symmetry of nature is still one of the great puzzles of particle physics. In fact, they showed that in the decays of long-lived K-mesons, CP is not an exact symmetry, which implies that T is violated too, if we believe the PCT theorem.