Johns Hopkins professor shares Nobel Prize in physics

Adam Riess researches expansion of the universe

October 04, 2011|By Frank D. Roylance, The Baltimore Sun

More than anything else, in the wake of the elation and tumult accompanying Tuesday's announcement that he'd won a share of the 2011 Nobel Prize in physics, Johns Hopkins University astrophysicist Adam Riess wants to get back to work.

"I really want to keep doing the research I do, and not just supervise people doing research," a fate that sometimes befalls Nobel laureates, he said.

His discovery of dark energy, and the accelerating expansion of the universe was, after all, something he accomplished in 1998 at the University of California Berkeley — at the age of 28.

Since then, he has moved to Hopkins and used powerful instruments on the Hubble Space Telescope to push even farther toward the edge of the visible universe, and toward unraveling the mystery of dark energy.

He's 41 now, and if Congress doesn't drop its funding for Hubble's successor, the James Webb Space Telescope, Riess hopes to use that orbiting observatory to finish the job. He has written a key paper proposing to use the embattled Webb observatory to push his observations back in space and time to get a look at the very first supernova explosions.

Riess, who also works at the Space Telescope Science Institute in Baltimore, will share the $1.49 million Nobel award with fellow American Saul Perlmutter and U.S.-Australian citizen Brian Schmidt.

Riess was the lead author on the first paper to describe the astonishing discovery — through his study of a type of exploding star called a Type 1a supernova — that the expansion of the universe is accelerating, driven by a still-unexplained force dubbed "dark energy." Perlmutter's team arrived at the same findings independently, but nearly simultaneously.

His teammate Schmidt, who now heads the Supernova Search Team at the Australian National University, and Perlmutter, who oversees the Supernova Cosmology Project at the University of California, will join Riess in December in Stockholm to receive what many consider the world's most prestigious prize.

The Royal Swedish Academy of Sciences selected the three scientists "for the discovery of the accelerating expansion of the universe through observations of distant supernovae," according to the announcement.

Hopkins President Ronald J. Daniels said Riess' research "made sense of an idea with which Albert Einstein himself never came to terms. It was like a missing piece in a puzzle that we have been assembling for generations."

He predicted that Riess would not pause long to bask in his new fame. "There is much we do not understand about dark matter, and Adam's research will continue to probe the unknown."

Matt Mountain, director of the Space Telescope Science Institute, said Riess' path to the Nobel began with an assignment to calculate the mass of the universe, "one of those boring projects you give to a grad student."

Boring, perhaps, but crucial to astrophysicists' attempts to calculate whether the universe would expand forever, or gradually slow, stop, and then begin to contract toward a "Big Crunch."

The number Riess came up with indicated that the universe had a negative mass, Mountain said. It meant that the universe's expansion, first observed in the 1920s, was actually accelerating. The "dark energy" was pushing everything in the universe apart.

Mountain said the finding was as astonishing to scientists as it would be if he tossed his car keys into the air, only to watch them accelerate into the sky instead of fall back to Earth.

"Anybody else would have said, 'I've screwed up my calculations,'" Mountain said. Instead, Riess went back and checked his calculations.

"There are 52 ways to do something wrong," Riess said. " I make two to three mistakes a day, on a good day. But I spent weeks looking for a mistake and I couldn't find it."

Satisfied his calculations were correct, he reported his astonishing find to the world.

Since then, other researchers have used a variety of observations to confirm Riess' conclusion. "It's gone from being a surprise, to being the new standard model," he said.

In 1999, Riess joined Hopkins and the Space Telescope Science Institute, where he has since used instruments on the Hubble Space Telescope. With them, he's peered deeper into the universe and back in time to find more of the most distant Type 1a supernovae ever seen, revealing the time before the "transitional" period when the acceleration began.

"That switchover could only be seen with the Hubble Space Telescope," Mountain said. "The switch is what convinced everybody that dark energy is real." And that, he added, "is probably what convinced the Nobel committee."

Mountain and Riess both gave credit Tuesday to U.S. Sen. Barbara A. Mikulski of Maryland for her political support for Hubble, and to NASA astronauts who risked their lives to keep it working.

Riess has since written a key argument for using the planned Webb Space Telescope to probe beyond the limits of the Hubble to reveal the beginnings of the universe's expansion.

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