The reionization of hydrogen in the universe didn't occur like the flipping on of a light switch; it wasn't instantaneous and probably didn't happen at the same rate across the cosmos, said Anna Frebel, an assistant professor of physics at MIT who studies stars and galaxies that formed in the very early days of the universe. (scientificamerican.com)
Go on a journey to the earliest days of the universe as astronomer Avi Loeb searches for the first stars. (discovermagazine.com)
We know that because the Wilkinson Microwave Anisotropy Probe (WMAP), launched in 2001, recently revealed the pattern of hot and cold spots in the heat left over from the earliest days of the universe. (discovermagazine.com)