Update, 10:52 a.m. Mar. 18 EDT: Video by Stanford University shows Professor Andrei Linde and his wife’s surprise when they are told for the first time there is evidence supporting cosmic inflation theory. “It just overwhelms,” Mr. Linde said. Original post follows.
Scientists believe that almost 14 billion years ago, the universe was a hot, dense place that rapidly expanded after the Big Bang. The idea that the universe underwent a rapid expansion is called inflation; the universe spread out and cooled down, forming atoms that later made gas, dust, stars and planets.
But what exactly happened at the start of the universe has been unconfirmed until now. With a radio telescope at the South Pole, scientists followed gravitational waves 13.8 billion years into the past and found the first direct evidence of the universe’s rapid expansion immediately following the Big Bang. Scientists discussed their findings at a press conference Monday at the Harvard-Smithsonian Center for Astrophysics.
“This is a totally new, independent piece of cosmological evidence that the inflationary picture fits together,” said theoretical physicist Alan Guth of MIT, who proposed the idea of inflation in 1980.
This is the first concrete evidence of gravitational waves, a phenomenon first predicted by Einstein 100 years ago. After major cosmic events like the merging of black holes or the Big Bang, gravity makes waves in spacetime that travel like ripples on a pond. These ripples travel at the speed of light, but Einstein thought they would be so feeble, they would be undetectable.
But scientists suspected that these ripples could still be found. Billions of years later, the waves are too weak to measure directly, so scientists have been looking for imprints left on the “cosmic microwave background”, a soup of elementary particles leftover from the Big Bang. A U.S.-led team, headed by scientists at the Harvard-Smithsonian Center for Astrophysics, along with the University of Minnesota, Stanford University, the California Institute of Technology and NASA’s Jet Propulsion Laboratory, used a specialized radio telescope called BICEP2 (which stands for Background Imaging of Cosmic Extragalactic Polarization) at the South Pole to hunt for the gravitational waves. The dry air, thin atmosphere and distance from cell phone and radio towers made the South Pole the ideal wave-hunting location.
The results will be submitted to a scientific journal this week for review and publication, said John Kovac of Harvard, who led the research project.
Theoretical physicist Lawrence Krauss of Arizona State University said if the evidence of gravitational waves is confirmed, the discovery “gives us a window on the universe at the very beginning,” when it was less than one-trillionth of a second old, he told the Associated Press. He added that the results still need to be confirmed, but this study is the “best hope” of proving the universe’s early growth spurt.
“It’s just amazing,” he said. “You can see back to the beginning of time.”