The cosmic microwave background, or CMB, went on to become one of the most important tools we have for studying the history of the universe. It’s hard to overstate its significance, both as an astronomical data set and as a technological achievement. We can now collect, analyze, and map the glow of the hot early cosmos. The first thing it tells us is: the hypothesis that the early universe was one big inferno, glowing with heat, is completely confirmed.
