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The University of Texas at Arlington |
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The University of Texas at Arlington |
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David M. Lee |
Abstract
Superfluidity in liquid helium 4 was discovered by Pyotr Kapitsa in the late 1930’s. In the following years, spectacular phenomena associated with superfluidity were revealed. The fountain effect, the creeping film, the cessation of boiling below 2.17 k, the frictionless flow through tiny cracks, quantum vortices, and persistent currents will be illustrated and discussed. Fritz London introduced the idea that superfluidity was associated with quantum mechanics on a macroscopic scale and suggested that its onset at 2.17 kelvin degrees above absolute zero was associated with Bose-Einstein condensation. In the late 1990’s, Bose-Einstein condensation was shown to occur in ultra cold gases of rubidium, sodium, hydrogen, etc. In the 1970’s, superfluid helium 3 was first observed at Cornell University at 2.6 millikelvin. Since helium 3 obeys Fermi-Dirac statistics, Bose-Einstein condensation cannot be directly involved. Valence electrons in superconducting metals also obey Fermi-Dirac statistics. The superfluidity in helium 3 and the superconducting electrons in metals are now known to be associated with pairing of the electrons or the helium 3 atoms. The pairs behave like Bose-Einstein particles, and ensembles of pairs exhibit properties closely resembling Bose-Einstein condensation. The dramatic experiments at Cornell University in 1972 leading to the discovery of superfluidity in liquid helium 3 will be described.
David Lee was born (1931) and raised in Rye, N.Y., a small town on the coast of Long Island Sound. He attended Harvard University, graduating in January 1952. After two years of military service during the Korean War, he attended graduate school in Physics, attaining a Masters degree from the University of Connecticut (1955) and a Ph.D. from Yale University in 1959. In January 1959 he joined the Physics department of Cornell University as an instructor. Over the years, he worked his way up through the ranks at Cornell and is now the James Gilbert White Distinguished Professor of the Physical Sciences at Cornell. In 1972, along with his two Cornell colleagues (Robert C. Richardson and Douglas D. Osheroff), he participated in the discovery of Superfluid 3He. For this work, the group of three was awarded the 1996 Nobel Prize in Physics as well as the Buckley Prize of the American Physical Society and the Simon Prize of the British Institute of Physics. In addition to his work on Superfluid 3He, David has been active in research on superconductivity, spin polarized atomic hydrogen gas, solid helium, liquid 3He-4He mixtures and matrix isolated free radicals. He is a member of the National Academy of Sciences (USA), a foreign member of the Russian Academy of Sciences, and a fellow of the American Academy of Arts and Sciences, the American Association for the Advancement of Science, the American Physical Society, and the British Institute of Physics.
