Two Americans were awarded this year's Nobel Prize for Physics on Tuesday for research that provides more evidence for the big bang theory of the universe and its origin.

John C. Mather of the NASA Goddard Space Flight Center in Greenbelt, Md., and George F. Smoot of the Lawrence Berkeley National Laboratory in California verified that theoretical predictions about the universe were accurate.

Gunnar Oquist of the Royal Academy of Science, left, and Per Carlson, chair of the Nobel Prize committee, announce in Stockholm that Americans John C. Mather and George F. Smoot won the Nobel Prize for Physics.
(Bertil Ericson/Associated Press)

The big bang theory holds that the universe exploded into existence about 14 billion years ago from a single point, eventually evolving into stars, planets and galaxies.

Award 'richly deserved'

The scientists' work has dramatically changed the study of the big bang and the universe, lifting it out of the realm of mathematical formulas, said  Raymond Carlberg, a professor of astronomy and astrophysics at the University of Toronto.

"Before, people were trying to confirm the big bang theory," Carlberg said. "This work transformed the field into precision cosmology … It means the big bang is real.

"This is the most exciting Nobel Prize in many years," he said. "It is richly deserved."

Carlberg's sentiments echoed those of Per Carlson, chair 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," Carlson said.

Mather, 60, and Smoot, 61, used NASA's cosmic background explorer (COBE)  satellite launched in 1989 to observe cosmic background radiation with a degree of precision not previously attained, Carlberg said.

What the scientists found using COBE was that the appearance of the radiation spectrum was exactly as predicted by a formula derived by physicist Max Planck more than a century ago.

The Nobel winners were also able to measure variations in the temperature of the universe, and observed ripples in light that helped explain how galaxies came together over time.

Winner surprised

Reached at his home in Berkeley, Calif., Smoot told the Associated Press he was surprised when he got the call from the Nobel committee in the middle of the night.

"I was surprised that they even knew my number," he said. "This is a great honour and recognition. It's amazing."

Mather said he was "thrilled and amazed" at receiving the prize.

"I can't say I was completely surprised, because people have said we should be awarded, but this is just such a rare and special honour," Mather said in a phone interview with the Nobel committee.

With files from the Canadian Press