Physicist shared Nobel for groundbreaking research on helium-3

Robert Richardson 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.

Richardson, who recently had a heart attack, died Tuesday in Ithaca, N.Y., at the age of 75.

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 that is thought to correspond to the cosmic “strings” believed to have been instrumental in formation of galaxies.