If the big bang is true, after the emission of light from the hydrogen plasma, the universe was still expanding. Why would we expect to see uniform radiation if earth very well could have formed outside of this hydrogen plasma. Then we would expect to see bits of background radiation coming from one direction. People sometimes answer this question by saying that the big bang happened everywhere and that where the earth is right now was a haze of hydrogen plasma 13.7 billion years ago. I do not see how one can assume this as since the universe expands we could have formed outside of the plasma and therefore should not expect to detect uniform background radiation.


1 Answer 1


We could not have formed "outside" the expanding universe, as there would not be any substance to form our galaxy, and solar system -including our Sun and planet.

  • $\begingroup$ Ok got it. This makes perfect sense but now I have to ask how do we know where we formed in this plasma? If we formed away from the center, then we would not expect uniform distribution of background radiation. Can someone help me out? $\endgroup$ Apr 14, 2014 at 21:58
  • $\begingroup$ And I wasn't saying that we could've formed outside if the expanding universe but rather outside of the plasma. The universe now is much large than it was filled with plasma, so the new space from the expansion was in fact outside of the plasma. $\endgroup$ Apr 14, 2014 at 22:00
  • $\begingroup$ @user3138766 There is no center: astronomy.stackexchange.com/questions/669/… $\endgroup$
    – called2voyage
    Apr 15, 2014 at 14:15
  • $\begingroup$ @user3138766 The plasma was evenly distributed throughout the early universe. There was no "outside of the plasma". $\endgroup$
    – called2voyage
    Apr 15, 2014 at 14:16

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