This year’s Breakthrough Prize in Fundamental Physics was awarded to the team behind NASA’s Wilkinson Microwave Anisotropy Probe, or WMAP, a space telescope that launched in 2001 to map the cosmic microwave background—the earliest, oldest light we can detect from the universe’s infancy. The WMAP team will split the $3 million award, with its leaders receiving the largest shares. One of those leaders, WMAP’s chief theorist David Spergel, sat down to speak with Scientific American about WMAP’s science and its legacy.