University of Hawaii High Energy Physics Group, courtesy AIP Emilio Segrè Visual Archives · Attribution

Shared the 2004 Nobel Prize in Physics with David Gross and Frank Wilczek for discovering asymptotic freedom — the surprising property, central to the modern theory of the strong nuclear force, that quarks interact more weakly the closer together they are, rather than the reverse. The finding, made while he was still a graduate student, became one of the foundations of quantum chromodynamics. He has taught theoretical physics at Caltech for decades since.