US physicist who with US physicists David M Lee and Robert Richardson was awarded the Nobel Prize for Physics in 1996 for the discovery of superfluidity in helium-3.
The noble gas (rare gas) helium exists as two isotopes, helium-4 and helium-3, of which helium-4 is the most abundant in nature. When cooled to two degrees above absolute zero, −273.15°C/−459.67°F, liquid helium-4 shows the property of superfluidity, but helium-3 does not. In a superfluid state, helium atoms no longer move in the random motion described by classical fluid dynamics, but move in a coordinated fashion as described by the laws of quantum physics. The most well known property of a superfluid is the loss of internal friction within the liquid, which allows it to flow up and out of a container.
Osheroff was a graduate student working with David M Lee and Robert Richardson, researching the properties of helium-3 at extremely low temperatures, when the team made their discovery in 1972. Osheroff noticed small changes in the internal pressure in a sample of helium-3 that had been cooled to within a few thousandths of a degree above absolute zero. The conclusion reached by the team was that they were observing a change in the state of the helium-3 liquid, from a fluid to a superfluid. Although this discovery in itself was important, it was found that helium-3 showed a number of characteristics that differed significantly from helium-4. It was found that the quantum laws of microphysics govern the behaviour of helium-3. These laws are usually only applicable to systems such as atoms and subatomic particles and this was the first time that scientists could compare their microscopic research results directly with a macroscopic system.
Osheroff was born in Aberdeen, Washington, USA. He became a researcher at Bell Telephone Laboratories in 1972 and was head of solid state and low temperature research there from 1982 until 1987. He received his PhD in physics from Cornell University, New York, in 1973. He became a professor of physics at Stanford University, California, in 1987.