A team of researchers working with the South Pole Telescope has detected a subtle distortion in the afterglow of the Big Bang -- the oldest light of the universe -- that is expected to reveal secrets about how the universe was formed.

The scientists observed some twisting patterns in the polarization of the cosmic microwave background, the light that last interacted with matter more than 400,000 years after the Big Bang. These patterns, known as B modes, are caused by gravitational lensing, a phenomenon that occurs when the trajectory of light is bent by massive objects, much like a lens focuses light.

“The detection of B-mode polarization by South Pole Telescope is a major milestone, a technical achievement that indicates exciting physics to come,” lead researcher John Carlstrom of the University of Chicago said in a statement.

According to the results, which were published in the journal Physical Review Letters, the cosmic microwave background is full of photons, or light particles, left over from the Big Bang that saturates all of space, at a temperature of minus 270 degrees Celsius.

Scientists said that light from the cosmic microwave background is polarized mainly due to the scattering of photons off of electrons in the early universe, through the same process by which light is polarized as it reflects off the surface of a lake. The polarization patterns are of a swirl-free type, known as E modes, which are easier to detect than the fainter B modes.

To tease out the B modes, the scientists used a previously measured map of the distribution of mass in the universe to determine where the gravitational lensing should occur. They combined their measurement of E modes with the mass distribution to provide a template of the expected twisting into B modes.

According to the scientists, the careful study of such B modes will help physicists better understand the universe. They believe that further examination of B modes would provide dramatic evidence of the theorized turbulent period in the moments after the Big Bang when the universe expanded extremely rapidly.

“The detection of a primordial B-mode polarization signal in the microwave background would amount to finding the first tremors of the Big Bang,” said Duncan Hanson, a postdoctoral scientist at McGill University and the study’s lead author.