A glow undetectable to the human eye permeates the universe. This light is the remnant signature of the cosmic beginning — a dense, hot fireball that burst forth and created all mass, energy, and time ...

So much happened in the earliest moments of the universe. Elementary particles appeared, the first nuclei of hydrogen and helium, and fluctuations of energy and matter set into motion the formation of ...

The cosmic microwave background can help scientists piece together the history of the universe. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works.