Swirls in Big Bang's Remnants Shed Light on Early Universe

The Big Bang caused our universe to form, creating stars and galaxies as creation began. Now, scientists have detected a subtle distortion in the oldest light in the universe, revealing new insights into the earliest moments of our universe's formation.

The researchers first saw this distortion by using the South Pole Telescope. That's when they spotted twisting patterns in the polarization of the cosmic microwave background, which is light that last interacted with matter very early in the history of the universe--less than 400,000 years after the Big Bang. These patterns are known as "B modes" and are caused by gravitational lensing, a phenomenon that occurs when the trajectory of light is bent by massive objects.

"The detection of B-mode polarization by South Pole Telescope is a major milestone, a technical achievement that indicates exciting physics to come," said John Carlstrom, one of the researchers, in a news release.

Light is polarized when its electromagnetic waves are preferentially oriented in a particular direction. 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 or the hood of a car. The polarization patterns that result are swirl-free and known as E modes. These are easier to detect than the fainter B modes.

In order to actual detect the B modes in their data, the researchers used a previously measured map of the distribution of mass in the universe in order to determine where the gravitational lensing should occur. In the end, they found that gravitational lensing can actually twist E modes into B modes as photons pass by galaxies and other massive objects on their way toward Earth.

The careful study of these B modes will allow physicists to better understand the universe. The patterns can be used to map out the distribution of mass and more accurately define cosmologically important properties. These properties include the masses of neutrinos, which are tiny elementary particles prevalent throughout the cosmos.

The findings are published in the magazine Physics World.