American physicist who was the corecipient, along with Douglas Osheroff (Osheroff, Douglas D.) and David Lee (Lee, David M.), of the 1996 Nobel Prize for Physics for their discovery of superfluidity in the isotope helium-3 (³He).

Richardson received his Ph.D. in physics from Duke University (Durham., N.C.) in 1966 and joined the faculty of Cornell University (Ithaca, N.Y.) in 1967. He became director of the laboratory of atomic and solid-state physics there in 1990.

At the time of their discovery in 1972, Richardson and Lee were senior researchers in the low-temperature laboratory at Cornell and were investigating the properties of the isotope helium-3. They had cooled a sample of helium-3 to within a few thousandths of a degree of absolute zero (−273° C) and were monitoring its internal pressure. Osheroff, a graduate student on the research team, noticed small jumps in the internal pressure that the researchers eventually explained as a phase transition to superfluidity. When a liquid becomes superfluid, its atoms lose their randomness and can flow in a coordinated manner. Helium-3 in this state lacks the internal friction that exists in normal liquids and thus flows without resistance. Because superfluid helium-3 is governed by the quantum laws of microphysics, it has allowed scientists to study directly in macroscopic—or visible—systems the quantum mechanical effects that previously could be studied only indirectly in such invisible particles as molecules, atoms, and subatomic particles.