Award Honors Cosmology Studies

This year's Nobel Prize in Physics goes to two American physicists for their precise measurements of a ubiquitous relic radiation, known as the cosmic microwave background (CMB) radiation, that is derived from the infant universe.

For their satellite-based investigations, which involved more than 1,000 collaborators, astrophysicist John C. Mather of NASA's Goddard Space Flight Center in Greenbelt, Md., and physicist George F. Smoot of Lawrence Berkeley National Laboratory and the University of California, Berkeley, will share about $1.3 million in prize money.

Despite its origin almost 14 billion years ago, the same radiation comprises part of the "snowy" static visible today on any television screen. By using the Cosmic Background Explorer (COBE) satellite, launched by NASA in 1989, Mather, Smoot, and their colleagues were able to precisely map the distribution and tiny fluctuations of this primordial microwave noise.

From those data emerged one of science's most iconic images-a veritable snapshot of the infant universe. "It is the accumulated trace of everything," Mather said in a taped interview with the Royal Swedish Academy of Sciences in Stockholm. Subsequent and ongoing work with the even more capable Wilkinson Microwave Anisotropy Probe, launched in 2001, has led to more refined views of CMB.

In the 1960s, two Bell Telephone Laboratories researchers, Arno Penzias and Robert W. Wilson, were the first to observe CMB, and they later received a Nobel Prize for that discovery. Theorists had long predicted that CMB, which harks from a time prior to the formation of stars and galaxies, ought to be somewhat nonhomogeneous.

That lack of homogeneity is what Smoot, Mather, and the other COBE researchers measured. At a press conference in 1992, they announced their discovery that CMB's temperature varies over the sky by parts per hundred thousand from its average temperature of 2.7 K. That value closely matches the temperature to which Big Bang theorists predicted the universe should have cooled from its earlier, hotter days.

The fluctuations correspond to tiny density differences in the early universe that ultimately evolved into the distribution of galaxies visible today. "We wouldn't have a home if these little hot and cold spots didn't exist," Mather said at a press briefing at NASA headquarters in Washington, D.C.

"The field of cosmology the day after COBE [results were announced] was different from the day before," says cosmologist Michael S. Turner of the University of Chicago. For one thing, the data "cemented the Big Bang Theory" because they agreed so well with theoretical predictions, Turner said.

"It also opened the door to this golden age of cosmology," he added, pointing out that researchers have been using COBE data to study the shape and age of the universe, its general composition, and when the first stars began to shine.