The cosmic microwave background is light left over from the big bang
Our first glimpse at the universe’s earliest stars may help us figure out what makes up dark matter. New observations have revealed hydrogen gas in the era when stars were just beginning to turn on, and the gas appears to have interacted with dark matter particles.
After the big bang but before stars and galaxies formed, most of space was filled with hydrogen gas that blended in with the background light remaining from the big bang – called the cosmic microwave background, or CMB – rendering it…
