The evidence is a type of polarization noticed in the oldest light in the universe, and the discovery was announced Monday by American scientists working on the BICEP2 project.
The polarization is proof of the gravitational waves, the distinct ripples in cosmic time that scientists say they've been looking for -- the "first tremors of the Big Bang."
Astronomers made the discovery using telescope imagery captured from the National Science Foundation-funded South Pole Station, which takes advantage of Antarctica's clear skies and stable views.
"This has been like looking for a needle in a haystack, but instead we found a crowbar," said co-leader Clem Pryke, of the University of Minnesota.
For some time, astronomers have been scouring the skies for proof that the beginnings of the universe included a rapid expansion, an explosion that happened in the first trillionth of a second of cosmic history and propelled the unimaginably small universe to grow to the size of a marble. It's been expanding slowly outward ever since, for 14 billion years.
BICEP2 is collaboration of several scientific investigations into the cosmic microwave background, the thermal radiation believed to be the footprint of that early explosion, and what scientists call the "oldest light in the universe."
Now, scientists say they found the polarization pattern they've been looking for -- the signature of gravitational waves in the cosmic microwave background.
Astronomers from the University of Minnesota, CalTech, Harvard and Standard all made the BICEP2 discovery possible.
"Our team hunted for a special type of polarization called 'B-modes,' which represents a twisting or 'curl' pattern in the polarized orientations of the ancient light," explained co-leader of the BICEP2 operation, Jamie Bock, of CalTech.
"Detecting this signal is one of the most important goals in cosmology today," said John Kovac, leader of the BICEP2 collaboration and researcher at the Harvard-Smithsonian Center for Astrophysics. "A lot of work by a lot of people has led up to this point."
Details of the BICEP2 discovery are published on the project's website.
[Harvard-Smithsonian Center for Astrophysics]