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05/07/2003 07:00:00

Caltech Faculty Member Named Scientist of the Year

PASADENA, Calif. — The California Science Center has announced the joint selection of Andrew Lange and Saul Perlmutter as 2003 California Scientist of the Year.

Lange is Marvin L. Goldberger Professor of Physics at the California Institute of Technology in Pasadena, and Perlmutter is senior scientist and group leader at the Lawrence Berkeley National Laboratory in Berkeley. Using two very different techniques, Lange and Perlmutter's experimental efforts have confirmed a remarkable theory of how the universe expanded and evolved after the "big bang."

Lange and Perlmutter will be recognized during the annual presentation of the California Scientist of the Year and the Amgen Award for Science Teaching Excellence, a special event to honor excellence in scientific achievement and education, on May 8 at the California Science Center in Exposition Park, Los Angeles.

Lange is the 14th Caltech faculty member to be named Scientist of the Year.

The California Science Center established the California Scientist of the Year Award in recognition of the prominent role California plays in the areas of scientific and technological development. A blue-ribbon panel selects a nominee whose work is current and advances the boundaries of any field of science. Of those selected for California Scientist of the Year honors, 11 later became Nobel laureates. The panel concluded that Lange and Perlmutter's discoveries complement each other so well in revealing the nature of the universe that both scientists should be recognized this year.

According to the most widely held theory of cosmic evolution, the universe went though an inflationary phase during which its size rapidly increased and the universe's geometrical structure took on a very specific form: parallel lines never meet, and the sum of the angles inside an astronomically sized triangle add up to 180 degrees. Scientists refer to this particular form of geometry as being mathematically "flat." According to the general theory of relativity, a mathematically flat universe places constraints on the amount of mass and energy in the universe. Unfortunately, astronomers could not account for the requisite mass and energy. Therefore, either the standard cosmological or—"big bang"—theory was incorrect and the universe's geometrical structure was not that of Euclid, or the astronomers were missing something important.

Lange studies fluctuations in the cosmic microwave background (CMB) radiation, a relic of the primeval "fireball" that filled the early universe. These signals, which are visible today at microwave frequencies, provide a clear "snapshot" of the embryonic universe at an epoch long before the first stars or galaxies had formed. In general, this radiation reaches the earth uniformly from all directions in the sky. However, at the level of 0.003 percent there is an intricate pattern of fluctuations in the CMB. Using novel detectors developed at the Jet Propulsion Laboratory and flown on a balloon-borne telescope high above Antarctica, Lange's group was able to make the first resolved images of these very faint patterns. The images demonstrate that the radiation fluctuates on an angular scale of one degree, which is exactly what scientists expected from a mathematically flat universe. Since the 1930s, scientists have known that galaxies are moving away from one another, and there has been a concerted effort to study the rate of this expansion. Prior to Perlmutter's efforts, almost all astronomers expected that the expansion of the universe was slowing, due to the gravitational attraction of galaxies and other matter. However, Perlmutter's group found that the universe is actually expanding at an accelerating rate, as if a "negative pressure" were pushing everything apart. This negative pressure may be what scientists call the cosmological constant, first hypothesized by Albert Einstein in an attempt to prescribe a stable universe but later rejected by him. Perlmutter's estimates of the cosmological constant's magnitude are consistent with Lange's observations of a flat universe.

Lange's work demonstrates that the universe is mathematically flat, and that the standard cosmological theory is correct, while Perlmutter's work indicates that the source of astronomical energy giving rise to a flat universe comes from a type of negative gravitational pressure or dark energy permeating the universe. The nature of this dark energy remains a mystery.

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