Rainwater, (Leo) James (1917–1986)

US physicist who with the Danes Aage Bohr and Ben Mottelson shared the Nobel Prize for Physics in 1975 for their discovery of the connection between collective and particle motion in atomic nuclei, and the development of the theory of nuclear structure.

Rainwater was born in Council, Idaho, and studied at the California Institute of Technology and at Columbia University, where he became professor of physics in 1952. During 1942–46, he worked on the Manhattan Project to construct the atom bomb.

In 1950 Rainwater wrote a paper in which he observed that most of the particles in the nucleus of an atom form an inner nucleus, while the other particles form an outer nucleus. Each set of particles is in constant motion at very high velocity and the shape of each set affects the other set. He postulated that if some of the outer particles moved in similar orbits, this would create unequal centrifugal forces of enormous power, which could be strong enough permanently to deform an ideally symmetrical nucleus. This was confirmed experimentally by Bohr and Mottelson, and paved the way for nuclear fusion.