Studies of universe’s expansion win physics Nobel
STOCKHOLM (AP) - Three U.S.-born scientists won the Nobel Prize in physics on Tuesday for overturning a fundamental assumption in their field by showing that the expansion of the universe is constantly accelerating.
Their discovery created a new portrait of the eventual fate of the universe: a place of super-low temperatures and black skies unbroken by the light of galaxies moving away from each other at incredible speed.
Physicists had assumed for decades that the expansion of the universe was getting ever-slower, meaning that in billions of years it would resemble today’s universe in many important ways.
Then, working in separate research teams during the 1990s, Saul Perlmutter, Brian Schmidt and Adam Riess found that the light from more than 50 distant exploding stars was far weaker than they expected, meaning that galaxies had to be racing away from each other at increasing speed.
The acceleration is driven by what scientists call dark energy, a cosmic force that is one of the great mysteries of the universe.
The Nobel-winning discovery implies instead that the universe will get increasingly colder as matter spreads across ever-vaster distances in space, said Lars Bergstrom, secretary of the Nobel physics committee.
He said galaxies that are 3 million light years away from Earth move at a speed of around 44 miles per second (70 kilometers per second). Galaxies that are 6 million light years away move twice as fast.
The research implies that billions of years from now, the universe will become “a very, very large, but very cold and lonely place,” said Charles Blue, spokesman for the American Institute of Physics.
In contrast to the big bang, that fate has been called the “big rip” to indicate how galaxies would be torn apart, he said.
Galaxies will be flying away so quickly that their light could not travel across the universe to distant observers as it does today, making the sky appear black, he said.
“For almost a century the universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago,” the citation said. “However the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the universe will end in ice.”
Riess, 41, is an astronomy professor at Johns Hopkins University and Space Telescope Science Institute in Baltimore, Maryland.