Scientists have puzzled over a curious cold spot that appeared in maps of the earliest light emitted in the universe. At first, this relic of the Big Bang was thought to be a sign of some cosmic collision, but according to new work, the cold spot appears to be a giant void -- the biggest known hole in the universe, New Scientist reports.
The cold spot appears in cosmic microwave background (CMB) maps of the infant universe (pictured above). The image shows 13.77-billion-year-old temperature fluctuations. After accounting for the cosmic growth spurt (or inflation), there’s still an unusually large cold region. Various theories requiring exotic physics or parallel universes surfaced. But here’s a simpler explanation: The cold spot was caused by a giant void in the universe.
A team led by István Szapudi at the University of Hawaii, Honolulu, conducted a hunt for the giant void using data from an all-sky survey made by NASA's Wide-field Infrared Survey Explorer (WISE) satellite. Radiation loses energy when it crosses dark, empty regions of very little matter, which surround the galaxies; this explains how a void could cause a cold spot in microwave maps.
In May, the team reported a giant void -- stretching 1.8 billion light-years across, possibly the largest one ever found -- in the direction of the cold spot, about 2.8 billion light years away. The cold anomaly, they say, is the shadow of a supervoid. Last month, the team bolstered their case by publishing various properties of the supervoid, including its alignment with the cold spot and its apparent depth.
[Via New Scientist]
Image: NASA/WMAP Science Team