Light and Matter in the big Bang
Most recent answer: 03/05/2016
- Jon Hammersberg (age 73)
Virginia Beach, VA USA
The picture isn't that at some spot in space there was light and matter and they blew outward like in a normal explosion. It's that all of space was filled very densely with hot matter and light. The whole space expanded, staying approximately uniformly filled. It cooled as it expanded. After it cooled enough, electrons and protons combined to make atoms, and these are almost transparent to light. So since then as the universe keeps expanding the light and the matter have gotten much less dense (more space to fill) but they are still approximately uniformly distributed on a large scale. On a smaller scale, the matter has formed lumps (like our galaxy) but the old light has stayed almost uniformly spread out. So wherever you are, there's some of it there. It's coming from all directions because it was always everywhere. There never was an "outside" where it was missing.
(published on 03/05/2016)