- Posted December 13, 2013 by
Swirls may lead clue to Universe's infancy
South Pole Telescope scientists have detected for the first time a subtle distortion in the oldest light in the universe, which may help reveal secrets about the earliest moments in the universe's formation.
The scientists observed twisting patterns in the polarization of the cosmic microwave background—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, 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.
Early today, Physics World magazine heralded the result as one of the top 10 physics breakthroughs of 2013.
A multi-institutional collaboration of researchers led by John Carlstrom, the S. Chandrasekhar Distinguished Service Professor in Astronomy & Astrophysics at the University of Chicago, made the discovery. They announced their findings in a paper published Sept. 30, 2013, in the journal Physical Review Letters—using the first data from SPTpol, a polarization-sensitive camera installed on the telescope in January 2012.
"The detection of B-mode polarization by South Pole Telescope is a major milestone, a technical achievement that indicates exciting physics to come," Carlstrom said.
The cosmic microwave background is a sea of photons (light particles) left over from the big bang that pervades all of space, at a temperature of minus 270 degrees Celsius—a mere 3 degrees above absolute zero. Measurements of this ancient light have already given physicists a wealth of knowledge about the properties of the universe. Tiny variations in temperature of the light have been painstakingly mapped across the sky by multiple experiments, and scientists are gleaning even more information from polarized light.
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 of a swirl-free type, known as "E modes," which have proven easier to detect than the fainter B modes, and were first measured a decade ago, by a collaboration of researchers using the Degree Angular Scale Interferometer, another UChicago-led experiment.