Scientist shared Nobel for superfluid research
Finding had immense impact on field of physics and helped shed light on universe’s first moments
Robert Richardson, who has died aged 75, shared the 1996 Nobel Prize in Physics with David Lee and Douglas Osheroff, for their discovery that at temperatures within two-thousandths of a degree of absolute zero, helium-3, a rare isotope of the chemical element helium, becomes a “superfluid” that flows without friction.
Superfluidity is a scientific term for when a liquid is made so cold that it loses its usual molecular patterns.
When a liquid becomes superfluid, its atoms become so well ordered that they behave, in effect, like a single atom and disobey the rules of classical physics. This allows them to flow without losing any energy to friction, climbing up and out of bottles and seeping through the tiny pores of ceramic containers.
The most common isotope of helium, helium-4, which has four nuclear particles, was known to be a superfluid, but Richardson and his colleagues, who made their breakthrough at Cornell University in 1972, were not expecting helium-3, with only three particles in its nucleus, to behave in the same way.
But as they investigated the molecular properties of frozen helium-3 ice, Osheroff, then a graduate student, noticed that the helium had begun to manifest the properties of a superfluid, after observing small, unexpected jumps on the monitors. “It is easy,” the Nobel committee observed, “to consider such small deviations as more or less inexplicable characteristics of the apparatus, but this student and his older co-workers became convinced that it was a true effect.”
Further research revealed, unexpectedly, that unlike other superfluids, superfluid helium-3 has two “phases” when the pressure and temperature are changed, causing the substance to manifest both properties of conventional superfluids and those of liquid crystals. This apparent duality allows it to exhibit a variety of spectacular magnetic, acoustic and hydrodynamic properties that do not exist in any other known materials.
The impact of this discovery on physics has been immense. In particular, it has helped to shed light on the first moments of the universe, as the physical transitions that occur as helium-3 becomes frictionless are similar to processes believed to have taken place a fraction of a second after the Big Bang. By rapidly heating then supercooling samples of helium-3, researchers have observed the formation of vortices — a process which is thought to correspond to the cosmic “strings” believed to have been instrumental in the formation of galaxies.
While the discovery of the superfluid properties of helium-3 has not yet yielded any practical applications, it is thought that the discovery might eventually enable scientists to understand superconductivity — whereby some substances at very low temperature can allow electric currents to flow forever without losing energy. Understanding this phenomenon is vital if superconductivity is ever to make good on its promises of cheap electric power and efficient magnets and motors.
The son of a telephone engineer, Robert Coleman Richardson was born on June 26, 1937 in Washington, D.C.
After finishing his thesis in 1965 he remained at Duke University for another year as a research associate before taking up an invitation to join Dave Lee and John Reppy at Cornell University’s Laboratory of Atomic and Solid State Physics, carrying out research on very low temperature helium.
Richardson became a Floyd Newman Professor of Physics and viceprovost for research at Cornell.
Richardson died Feb. 19.