By Marc Kaufman
Washington Post Staff Writer
Wednesday, October 4, 2006
Americans John C. Mather and George F. Smoot won the 2006 Nobel Prize in physics yesterday for producing the first tangible evidence that the universe began billions of years ago with the long-theorized big bang.
Using pioneering data from a NASA satellite they helped design and create, the two produced measurements that confirmed an essential aspect of the big-bang scenario -- that a cosmic bath of microwaves emanated from that original event and has been expanding and cooling ever since.
The Nobel committee praised their findings as a scientific turning point, one that changed cosmology from a theoretical science into one in which precise measurements and conclusions are possible.
Mather, 60, a Hyattsville resident and a senior astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, was the principal investigator for the groundbreaking Cosmic Background Explorer (COBE) satellite and experiments in 1989. Smoot, 61, an experimental astrophysicist at the Lawrence Berkeley National Laboratory in Berkeley, Calif., played a key role in the highly complex work of analyzing the data.
"They have not proven the big-bang theory, but they give it very strong support," said Per Carlson, chairman of the Nobel Committee for Physics. "It is one of the greatest discoveries of the century; I would call it the greatest. It increases our knowledge of our place in the universe."
The research propelled Mather and Smoot to instant scientific renown, with some describing their findings as evidence of a moment of "creation." At a 1992 news briefing on their discoveries, Smoot famously said that "if you're religious, it's like seeing God."
Mather put it differently yesterday. "What we're looking at is a tremendous mystery," he said of the beginnings of the universe. "We can work to describe it, but we cannot really explain it. . . . What we found is traces of the very earliest moment of time."
With the help of the COBE experiments, a scientific consensus has formed that the universe is about 13.7 billion years old.
Mather is the first NASA civil-servant scientist to win the Nobel Prize, but he is hardly the first federal employee to claim the most prestigious award in science. About one-quarter of the 270 Americans who have won Nobels were employed by the government.
Since 1986, Americans have won the physics prize, or shared it with people from other nations, 15 times.
The COBE satellite experiments resulted in the first detection of faint temperature variations in the cosmic microwave background, the haze of radiation representing the first light able to move freely after the big bang.
Those tiny differences in temperature are essential to explain how stars and galaxies formed. If the energy and radiation emanating from the big bang had been uniform, scientists theorized, the universe would not have materialized as it did. Before COBE, however, attempts to find temperature variations or "ripples" in the microwave background had failed.
So when the COBE results were presented at an American Astronomical Society meeting in 1993, they triggered gasps and later an ovation from the assembled scientists. The work was considered a great feat of experimental science because the faint temperature variations had to be distinguished from background radiation from the solar system, the galaxy and other celestial objects. In addition, the Earth's motion around the sun and the sun's movement around the Milky Way had to be taken into account.
The discovery involved measuring an energy called "blackbody radiation." In its press release, the Nobel committee said that immediately after the big bang, the universe could be compared to a glowing body emitting radiation in which the wavelengths depended solely on its temperature. That form of blackbody radiation was almost 3,000 degrees Celsius (5,432 degrees Fahrenheit) when it was first released.
Scientists had long believed that the radiation gradually cooled as the universe expanded, but Mather and Smoot were the first to measure the temperature of the background radiation. The result was an extremely frigid 455 degrees below zero Fahrenheit.
Following their work, scientific skepticism about the big-bang theory largely disappeared.
The $1.4 million prize was a boost not only for the two winning scientists, but also for NASA scientists in general. Since President Bush announced plans two years ago to send astronauts back to the moon and eventually to Mars, the agency's science programs have been losing budget battles, leading to concern about their future.
Edward Weiler, director of the Goddard Space Flight Center, welcomed the news by saying it is "important to note that COBE was built entirely 'in-house.' " He added: "The fact that a NASA civil servant has won the biggest science award possible demonstrates that world-class research is happening here at NASA."
Scientists have theorized since the 1960s about the existence and importance of cosmic microwave background, and COBE was built at Goddard to measure faraway microwave and infrared light detectable only from outside Earth's lower atmosphere.
The COBE data were analyzed by a team, led by Smoot, that produced maps of the entire sky showing "hot" and "cold" regions with temperature differences of a hundred-thousandth of a degree.
"At the time captured in our images, the currently observable universe was smaller than the smallest dot on your TV screen," Smoot said yesterday.
Since the prizewinning discovery, other astrophysicists have expanded knowledge about the cosmic background radiation and measured it even more precisely. But Mather said yesterday that the next big discoveries are likely to come from NASA's James Webb Space Telescope mission, which is scheduled to launch in 2013. Mather is the mission's senior project scientist.