A Polarized UniverseThe CMB polarization was produced as light scattered off a primordial cloud of protons and electrons nearly 14 billion years ago, about 400,000 years after the Big Bang. This marks the moment of recombination, when the universe finally cooled enough to allow electrons to join protons. The CMB is the light that broke through the fog.
Wanjek, Christopher (NASA Goddard Space Flight Center Greenbelt, MD, United States)
August 21, 2013
January 1, 2003
Publication: Space Science Reference Guide, 2nd Edition