reionization

When did the Universe first become transparent?  It’s a weird question, but an important one. The Universe started off opaque, but became transparent some time after, and remains that way even today. It’s literally…

For tens of millions of years, our newborn Universe was shrouded in hydrogen. Bit by bit, this vast mist was torn apart by the light of the very first stars in a dawn that defined the shape of the emerging cosmos.  Having a timeline for…