US physicist who with US physicists David M Lee and Douglas D Osheroff was awarded the Nobel Prize for Physics in 1996 for the discovery of superfluidity in helium-3.
The first discovery of a superfluid occurred in the late 1930s. Researchers cooled an isotope of helium, helium-4, to several degrees above absolute zero, −273.15°C/−459.67°F, and observed that the liquid no longer behaved as it should if governed by the classic laws of fluid dynamics. The liquid possessed no internal friction and flowed without resistance. Its behaviour could only be described by referring to quantum physics and became known as a superfluid or quantum liquid. Although the helium-3 isotope did not behave as a superfluid at the same temperature as helium-4, theory predicted that helium-3 could be made into a superfluid if it could be cooled to a low enough temperature. However, despite the work of many research groups, no one had succeeded in this task and eventually it was thought to be impossible.
In 1972, Richardson and his associates Osheroff and Lee had been studying the properties of the isotope helium-3 that had been cooled to within a few thousandths of a degree above absolute zero, when Osheroff reported seeing unexpected jumps in the internal pressure of the liquid. Instead of discounting these small fluctuations as an error with their apparatus, the team became convinced that they were witnessing the phase transition between the normal helium-3 liquid and its superfluid state. Further research confirmed their findings and showed that they had succeeded in making helium-3 into a superfluid. The discovery of helium-3 superfluidity has helped scientists to refine their theories of matter at the microscopic level.
Richardson was born in Washington, DC, USA. He received his PhD in physics from Duke University, North Carolina, in 1966. He joined the faculty at Cornell University, New York, in 1967, and was appointed as the director of the Atomic and Solid-State Physics Laboratory at Cornell in 1990.