Researchers say they have spotted evidence that a split-second after the Big Bang, the newly formed universe ballooned out at a pace so astonishing that it left behind ripples in the fabric of the cosmos.
If confirmed, experts said, the discovery would be a major advance in the understanding of the early universe. Although many scientists already believed that an initial, extremely rapid growth spurt happened, they have long sought the type of evidence cited in the new study.
The results reported Monday emerged after researchers peered into the faint light that remains from the Big Bang of nearly 14 billion years ago.
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The discovery "gives us a window on the universe at the very beginning," when it was far less than one-trillionth of a second old, said theoretical physicist Lawrence Krauss of Arizona State University, who was not involved in the work.
"It's just amazing," Krauss said. "You can see back to the beginning of time."
Marc Kamionkowski, a theoretical physicist at Johns Hopkins University who did not participate in the research, said the finding is "not just a home run. It's a grand slam."
He and other experts said the results must be confirmed by other observations, a standard caveat in science.
Right after the Big Bang, the universe was a hot soup of particles. It took about 380,000 years to cool enough that the particles could form atoms, then stars and galaxies. Billions of years later, planets formed from gas and dust that were orbiting stars. The universe has continued to spread out.
Krauss said he thinks the new results could rank among the greatest breakthroughs in astrophysics over the last 25 years, such as the Nobel prize-winning discovery that the universe's expansion is accelerating.
Monday's findings were announced by a collaboration that included researchers from the Harvard-Smithsonian Center for Astrophysics, the University of Minnesota, Stanford University, the California Institute of Technology and NASA's Jet Propulsion Laboratory. The team plans to submit its conclusions to a scientific journal this week, said its leader, John Kovac of Harvard.
Astronomers scanned about 2 percent of the sky for three years with a telescope at the South Pole, where the air is exceptionally dry.
They were looking for a specific pattern in light waves within the faint microwave glow left over from the Big Bang. The pattern has long been considered evidence of rapid growth, known as inflation. Kovac called it "the smoking-gun signature of inflation."
The reported detection suggests that "inflation has sent us a telegram," Kamionkowski said.
The researchers say the light-wave pattern was caused by gravitational waves, which are ripples in space and time. If verified, the new work would be the first detection of such waves from the birth of the universe, which have been called the first tremors of the Big Bang.
Krauss cautioned that the light-wave pattern might not be a sign of inflation, although he stressed that it's "extremely likely" that it is. The pattern is "our best hope" for a direct test of whether the rapid growth spurt happened, he said.
Alan Guth of the Massachusetts Institute of Technology, a creator of the idea of inflation, said the findings already suggest that some ideas about the rapid expansion of the universe can be ruled out.
It had not been clear whether the light-wave pattern would be detectable even if inflation really happened, he said, but luckily "nature is cooperating with us, laying out its cards in a way that we can see them."