SPACE - Early universe 'warmed up' later than previously believed: Research suggests a way to detect the earliest black holes

A new study reveals that black holes, formed from the first stars in our universe, heated the gas throughout space later than previously thought. They also imprinted a clear signature in radio waves which astronomers can now search for. The study is a major new finding about the origins of the universe ...

http://www.sciencedaily.com/releases/2014/02/140205143802.ht