Feynman, Richard P(hillips)

US physicist whose work laid the foundations of quantum electrodynamics. He was awarded the Nobel Prize for Physics in 1965 for his work on the theory of radiation. He shared the award with Julian Schwinger and Sin-Itiro Tomonaga. He also contributed to many aspects of particle physics, including quark theory and the nature of the weak nuclear force.

For his work on quantum electrodynamics, he developed a simple and elegant system of Feynman diagrams to represent interactions between particles and how they moved from one space-time point to another. He derived rules for calculating the probability of the interaction represented by each diagram. His other major discoveries are the theory of superfluidity (frictionless flow) in liquid helium, developed in the early 1950s; his work on the weak interaction (with US physicist Murray Gell-Mann) and the strong force; and his prediction that the proton and neutron are not elementary particles. Both particles are now known to be composed of quarks.