Wieman, Carl Edwin, << WY muhn, kahrl EHD wihn >> (1951-…), an American physicist, won a share of the 2001 Nobel Prize in physics for discovering and studying a state of matter known as a Bose-Einstein condensate (BEC). A BEC is a cluster of atoms that behave somewhat as if they were a single atom. Wieman shared the prize with his colleague, the American physicist Eric A. Cornell; and with the German physicist Wolfgang Ketterle, who worked separately on BEC’s. The condensates are named for the physicists Satyendra Nath Bose of India and Albert Einstein of Germany, who proposed in the 1920’s that BEC’s could be created.
The creation and behavior of a BEC can be explained in terms of the wave-particle duality of matter. We commonly consider an atom to be made up of solid particles. But an atom also has properties of a wave. One of those properties is wavelength, the distance between successive wave crests. The wavelength of an atom depends on the atom’s momentum—_that is, its total amount of motion. The smaller the momentum, the larger the wavelength. An atom’s momentum, in turn, equals the _mass of the atom times the atom’s velocity. The atom’s mass is its amount of matter; its velocity is its speed in a particular direction.
Wieman and Cornell created BEC’ s by decreasing the velocity of atoms in a gas. As the velocity decreased, the wavelengths of the atoms became larger. Eventually, the wavelengths became approximately as large as the distances between the atoms. When that occurred, all the atoms suddenly began to move at one velocity. The entire cluster of atoms took on the properties of a single wave, thereby becoming a BEC.
Wieman and Cornell created their BEC’s in a gas consisting of rubidium atoms. The scientists cooled the gas to less than 35 billionths of 1 degree Fahrenheit above absolute zero (–459.67 °F or –273.15 °C). Cooling a gas is equivalent to decreasing the velocity of its atoms; the temperature of a gas is a measure of the average energy of motion of its atoms.
The scientists decreased the velocity of the rubidium atoms by bombarding them with light. According to wave-particle duality, light can be thought of as consisting of waves or of particles called photons. A photon has zero mass, but it possesses momentum. Wieman and Cornell forced photons to collide head-on with the rubidium atoms, thereby slowing the atoms.
Wieman was born in Corvallis, Oregon, on March 26, 1951. In 1977, he obtained a Ph.D. degree in physics at Stanford University in California. He then became an assistant research scientist at the University of Michigan. Wieman was named an assistant professor at Michigan in 1979 and an associate professor in 1984. In 1985, he also became a fellow at JILA, a research institute in Boulder, Colorado. JILA was originally known as the Joint Institute for Laboratory Astrophysics. Today, only the abbreviation is used. JILA is operated jointly by the National Institute of Standards and Technology and the University of Colorado.
In 1987, Wieman became a professor of physics at the University of Colorado in Boulder. Wieman and Cornell first created BEC’s in 1995 at JILA.
See also Cornell, Eric Allin ; Ketterle, Wolfgang .
