Osheroff, Douglas Dean (1945-...), is an American physicist who specializes in ultralow temperature physics. In 1972, he was one of a team of physicists who discovered that helium-3, a rare type of helium, becomes a superfluid when it is extremely cold. A superfluid flows without any internal friction, unlike ordinary liquids. The team had to cool the helium-3 to about two-thousandths of a degree Celsius above absolute zero. Absolute zero is the lowest temperature that scientists believe is possible. For this discovery, Osheroff shared the 1996 Nobel prize for physics with colleagues David Lee and Robert Richardson.