Lee, David Morris (1931-…), is an American physicist who specializes in ultralow temperature physics at Cornell University . 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 is an exotic state of matter that acts like a liquid that flows absolutely freely. 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, Lee shared the 1996 Nobel Prize for physics with colleagues Robert Richardson and Douglas Osheroff .
Lee was born in Rye, New York . He went to Harvard University in 1949 and briefly considered a career in medicine , but decided to major in physics. He graduated in 1952. He moved to Connecticut for graduate study in physics, beginning a Ph.D. course at Yale University in 1955. For his Ph.D. thesis, he studied liquid helium-3, a substance which was the subject of his Nobel Prize-winning research many years later.
In January 1959, Lee returned as a faculty member to Cornell University in Ithaca, New York, where he set up a low-temperature laboratory. In November 1971, Lee, his colleague Robert Richardson, and a doctoral student named Douglas Osheroff, experimented with helium-3 cooled so close to absolute zero that it was partly solid and partly liquid. The material behaved strangely. In one experiment, the pressure was steadily changed over time. Osheroff noticed small jumps in the graph of pressure. In 1972, the team established that the pressure jumps were due to changes in the helium-3, making its change to a superfluid. The team had discovered the first of three superfluid phases of liquid helium-3. Because the atoms in superfluid helium-3 lose all their randomness and move in a coordinated manner, the fluid can flow up and out of an open container. Although its behavior was complex, they could explain it in terms of a theory of physics called the BCS theory. The theory explains superconductivity , the loss of electrical resistance by some materials when cooled to extremely low temperatures.
Lee’s group at Cornell went on to discover much more about the behavior of matter at low temperatures. Its studies included magnetism in solid helium-3 and the persistence of movement in superfluids.
