Riess, 36, who is also an astronomer at the Space Telescope Science Institute, said he learned of the award in an e-mail message from a journalist in Hong Kong asking for an interview. Later, a colleague called his home.
"He said, 'There's a thing on the fax machine'" from the Hong Kong-based Shaw Prize Foundation saying he had won a share of $1 million, Riess said. "I'm like, 'OK, hang onto that.'"
This is the third year for the Shaw Prize, awarded annually in three fields: astronomy, life science and medicine, and mathematical sciences. The prize was established by Run Run Shaw, a philanthropist and longtime leader in the Hong Kong film and television business. This year's presentation ceremony will be held Sept. 12.
Co-winners of the 2006 astronomy prize with Riess are Saul Perlmutter of the Lawrence Berkeley Laboratory of the University of California, Berkeley, and Brian Schmidt of the Mount Stromlo Observatory of the Australian National University in Canberra.
Riess and Schmidt were leaders of one team that pursued highly difficult and challenging measurements that led to the dark energy discovery in 1998. Perlmutter was the leader of a competing team.
"We set out to measure the expansion rate of the universe in the past and compare it to the expansion rate of the present universe, using exploding stars called supernovae," Riess said. They expected to find that gravity -- the force by which everything in the universe tugs at everything else and tends to attract it all together -- had slowed the rate of expansion over time.
"So it was startling to find that the expansion rate was speeding up," Riess said.
That, he said, sent astronomers back to an idea developed but eventually discarded by Albert Einstein as "my biggest blunder." That idea, Riess said, implied that there might be a sort of "anti-gravity" -- that "the vacuum of space had energy in it and that energy could act repulsively and accelerate the expansion of the universe."
"Today, we call this phenomenon 'dark energy,'" he said. Though it may account for 70 percent of the universe, "we still don't understand it very well," he said.
A 2003 National Academy of Sciences report referred to the nature of dark energy as "the deepest mystery in physics" and said, "Its resolution is likely to greatly advance our understanding of matter, space, and time."
Riess said he, his colleagues and many other astronomers are working to learn more, using the Hubble Space Telescope and ground-based experiments. In 2003, for example, Riess announced results from Hubble observations of Type 1a supernovae. The new results indicated that a "cosmic jerk" occurred 5 billion years ago, a transition from a state in which gravity was predominant, putting the brakes to universal expansion, to a state in which dark energy took over and began accelerating the expansion.
Riess and others are working with NASA and the Department of Energy to explore the possibility of a Joint Dark Energy Mission, a satellite with an array of instruments that would be dedicated to exploring dark energy.
Riess, previously an adjunct associate professor, joined the Johns Hopkins physics and astronomy faculty full-time in January. He also has been an astronomer since 1999 with Baltimore's Space Telescope Science Institute, the science headquarters of the Hubble Space Telescope. From 1996 to 1999, he was a Miller Fellow at the University of California, Berkeley.
Riess is a 1992 graduate of MIT, with a major in physics and a minor in history. He earned his doctorate in astrophysics from Harvard University in 1996.
Related Web sites:
Adam Riess Web page at Space Telescope Science Institute: http://www-int.
Shaw Prize: http://www.
Joint Dark Energy Mission: http://spacescience.
Media contact: Dennis O'Shea