Americans John Mather and George Smoot won the 2006 Nobel prize for physics on Tuesday for finding the background radiation that finally nailed down the Big Bang theory of the origin of the universe.
The Royal Swedish Academy of Sciences, which awarded the 10 million Swedish crown ($1.37 million) prize, said the two men were instrumental to the success of the cosmic background explorer (COBE) satellite programme launched by NASA in 1989.
Their work took the Big Bang theory, which holds that the universe began 14 billion years ago as a tiny dot that exploded into today's huge system of stars and planets, out of the realm of mathematical equations.
"Cosmology now is a precision science," said Lawrence Krauss, a theoretical physicist at Case Western University in Ohio.
"It cemented what we call the hot big bang model," added Michael Turner, an astronomer and astrophysicist at the University of Chicago.
When Mather and Smoot's research was published in 1992, famed cosmologist Stephen Hawking called it the "greatest discovery of the century, if not of all time."
Mather gave credit to his whole team.
"In total there were 1,500 people, so it's a huge team effort that we're recognizing today," he told Reuters.
"We knew it was important. Now everybody knows it's important," Mather told a news conference later.
"It is extremely important for human beings to know their origins and their place in the world," added Smoot.
COOLING UNIVERSE
The so-called blackbody radiation they looked at allowed the laureates to show the universe had cooled from its initial fiery 3,000 degrees centigrade (5,430 degrees Fahrenheit) to a chill 2.7 degrees Kelvin above absolute zero.
Their measurements also showed temperature variations in background radiation in space, in the range of a hundred-thousandth of a degree, that offered clues as to how galaxies, stars and planets were formed as matter coalesced.
These "ripples" in space provided new clues about galaxy and star formation and why matter had been concentrated in a specific place rather than spreading out.
"Tiny variations in temperature could show where matter had started aggregating. Once this process had started, gravitation would take care of the rest: matter attracts matter which leads to stars and galaxies forming," the Academy said.
Mather, 60, coordinated the COBE programme and spearheaded one of its key experiments, while astrophysicist Smoot, 61, of the University of California, Berkeley, was responsible for measuring small temperature variations in the radiation.
Smoot told Reuters the Nobel committee called him after first dialing the wrong number. "I was particularly surprised because my phone is unlisted," he told a news conference.
Neither Smoot nor Mather had immediate plans for the prize money. "The upside though is that maybe now my students will pay more attention to me," Smoot said.
Mather said he was already pressing forward in the search for the universe's origins as Senior Project Scientist for the James Webb Space Telescope, an infrared telescope that will be able to search beyond the limits the Hubble Space Telescope can now observe.
"The mystery of the universe is not completely solved," Smoot said. "Our ignorance has never been greater, because our knowledge has never been greater."
(For a list of winners of the Nobel Prize in Physics over the last 10 years, please see NOBEL-PHYSICS-WINNERS-RECENT (FACTBOX). Reuters Xtra subscribers can see the factbox by double-clicking on [nL03250847]) (Additional reporting by Anna Ringstrom, Gelu Sulugiuc and Niklas Pollard in Stockholm, Adam Tanner in San Francisco and Jackie Frank and Maggie Fox in Washington).
