This episode is about the The Sunyaev–Zel'dovich Effect, where photons from the big bang are used to backlight giant galaxy clusters! My Physicists this episode are Dr. Michael Zemcov, and Dr. Danica Marsden. Our guest this time is TED LEO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! WOO! THE COSMIC MICROWAVE BACKGROUND!