Three scientists won the Nobel Prize in Physics for discovering that the universe’s expansion is accelerating, shattering their own expectations and raising questions about the dark energy behind the surge.

Saul Perlmutter

Competing teams, one begun by Perlmutter in 1988, the other by Schmidt six years later, set out to study the most distant exploding stars, known as supernovae, according to the academy. They found that the universe’s expansion was accelerating, confounding their expectations that the pull of gravity would cause it to slow. Riess worked on Schmidt’s team.

“You get a lot of results in astronomy and physics that are said to be groundbreaking, but this was one that really, genuinely was," Steve Rawlings, a professor of astrophysics at the University of Oxford in England, said in a telephone interview on Tuesday. “It’s a whole new component of the universe that we just didn’t know about before."

“The acceleration led scientists to speculate about the existence of a mysterious force called dark energy that is pushing the universe apart," the academy said.

Brian P. Schmidt

“I feel weak at the knees," said the researcher, who is a U.S. and Australian citizen. “I guess it’s one of those things, occasionally people mention it but you think it is probably never going to happen."

Perlmutter said a journalist woke him in his Berkeley home with the news. “It was fun to explain something that was just so basic," he said in a telephone interview. “When we started this project we thought we were measuring how much the universe was slowing down, but it’s just getting faster and faster."

“The research raises the question of why the universe would have this odd property," said Perlmutter, who was born in Champaign-Urbana, Illinois. “You might expect gravity would slow it down, but it’s just expanding faster and faster."

Riess, who was born in Washington and grew up in New Jersey, won a so-called genius grant from the John D. and Catherine T. MacArthur Foundation in 2008. He was half awake when the call came from Stockholm because his 10-month-old son had woken up. “There was this Swedish sounding voice on the phone," said Riess. “I knew it wasn’t Ikea. I quickly realized the magnitude of it."

Adam G. Riess

Annual prizes for achievements in physics, chemistry, medicine, peace and literature were established in the will of Alfred Nobel, the Swedish inventor of dynamite, who died in 1896.

The Nobel Foundation was established in 1900 and the prizes were first handed out the following year. The first Nobel in physics was awarded to Wilhelm Roentgen for his discovery of X-rays. Bloomberg

—Johan Carlstrom in Stockholm has contributed to the article

Photographs by AP/Bloomberg