Quasars fingered for cosmic climate change

Light from distant galaxies shows that a heatwave struck the universe 12 billion years ago

URL: http://feeds.newscientist.com/c/749/f/10898/s/fa15d02/l/0L0Snewscientist0N0Carticle0Cmg20A8278650B10A0A0Equasars0Efingered0Efor0Ecosmic0Eclimate0Echange0Bhtml0DDCMP0FOTC0Erss0Gnsref0Fspace/story01.htm