What’s cosmic microwave background radiation? What does it tell us about the history of the universe? After the Big Bang, all of the universe’s matter comprised a sea of hydrogen and helium gas so dense that any light it gave off was quickly reabsorbed. A universal dark age began that would last nearly 400,000 years. Then, the cosmos began to glow. Read more to learn about this glow that we can still observe today and to understand what it tells us about the universe and its history.
Microwave Background Radiation: When the Cosmos Glowed
