Just as Charles Darwin once used the fossil record to tell the story of the evolution of life on Earth, astronomers are using the first light ever to shine through the universe to understand events that have shaped the cosmos.
This first light is called the "Cosmic Microwave Background (CMB)," leftover radiation which is spread almost evenly through the universe. The CMB carries with it the signatures of the physical processes of the early universe and possesses unique features that can be used to determine the make-up of the universe.
