Baltimore astronomer Adam Riess, the lead author on the 1998 paper that first reported that the expansion of the universe is accelerating, will share in the $500,000 Peter Gruber Cosmology Prize for 2007.
The unrestricted cash award and gold medal are given annually to scientists for "theoretical, analytical, or conceptual discoveries leading to fundamental advances in the field," according to the foundation's Web site, where the selection was made public yesterday.
Riess holds dual appointments at the Johns Hopkins University and the Space Telescope Science Institute.
The prize is described by Hopkins as "one of the most prestigious prizes in cosmology" and by PhysicsWeb as "the world's only award for cosmology."
Whichever way you look at it, "it's quite a nice honor," said Riess, 37. "I'm very happy about it."
Cosmology is the study of the origins and evolution of the universe as a whole, whereas astronomy concentrates on celestial objects such as planets, stars and galaxies.
Last year, Riess and two co-discoverers shared the $1 million Shaw Prize, an international award for groundbreaking discoveries in astronomy, mathematics, life sciences and medicine.
He split the Shaw Prize with Brian P. Schmidt of Australian National University and Saul Perlmutter of the University of California, Berkeley.
Schmidt led the High-z Supernova Search team. Riess - then at the University of California, Berkeley - was a member and first author of the High-z group's 1998 paper in the journal Science. Also on that team was Space Telescope Science Institute astronomer Ronald Gilliland.
Perlmutter led the competing Supernova Cosmology Project, which shared in the discovery, but published second, in 1999. Institute astronomers Andrew Fruchter and Nino Panagia also were part of Perlmutter's team.
The two papers are among the most cited of the past decade in physics and astronomy.
The two groups have agreed to split the Gruber award in half, with all 51 team members on the two teams receiving shares.
But, Riess stressed, "It's not about the money. ... It gets people focused on the wrong thing."
At the time of the original discovery, Riess was a young astronomer analyzing the light from a collection of exploding stars called Type 1a supernovae. He was trying to calculate their distance from Earth and the speed at which they were receding with the expansion of the universe.
To his puzzlement, it looked as though the more distant supernovae were moving away more slowly than those that were nearer to Earth in space and time.
The implication was that the expansion of the universe has been accelerating for billions of years. And that flew in the face of cosmologists' assumptions at the time - that gravity ought to be gradually slowing the expansion, just as balls tossed in the air will slow before falling again.
Something - it came to be called "dark energy" - is repelling all the matter in the universe. It was an idea first articulated by Albert Einstein, who later rejected it as his "biggest blunder."
Riess thought at first that there must be a glitch in his own math. But the more his team members checked and rechecked, the more they became convinced the acceleration was real.
"When I was writing that paper 10 years ago, I had no idea this would remain true," he said. "Most things in science that are really surprising are wrong."
Once his team had published, he thought someone else would find an error in their work. No one did. "If anything, the evidence has gotten a lot stronger," he said.
"I think of this as the end of the beginning for cosmology," Riess said. "Now, for the first time, we have plumbed the depths of the universe and identified all the first constituents."
Scientists believe that dark energy constitutes 70 percent of all the matter and energy in the universe. But it remains a mystery.
"Everybody has been working on follow-up studies. What is this stuff, and what is its nature?" Riess said. "It's a huge industry now. Many people think of it as one of the two hottest things" in physics and astronomy.
The second would be the search for planets - and ultimately habitable, or inhabited planets - around distant stars.
Riess has said he once worried aloud to his mother that he had peaked too early in his career. But "that was the concern of a 29-year-old," he said, laughing. "I've come to realize over time how rare these discoveries are, and I've learned to appreciate it more. ... You're lucky to get such a mystery in your time to work on."
In 1999, Riess moved to the Space Telescope Science Institute in Baltimore to continue his work, using the Hubble Space Telescope. He and his colleagues began publishing more results, adding evidence to support their discovery.
Last year, he also joined the faculty at Hopkins, where he is a professor in the Henry A. Rowland Department of Physics and Astronomy.
The Gruber Prize is named for philanthropist Peter Gruber, who fled Hungary with his family just before World War II and made his fortune on Wall Street.
His foundation, based in the U.S. Virgin Islands, funds annual, $500,000 prizes for work in cosmology, genetics, justice, women's rights and neuroscience. It also supports charitable work in education and social services in the Virgin Islands.firstname.lastname@example.org