I understand the concept of galaxies moving away from us at faster than the speed of light so that they lie outside of a "cosmic horizon" which we cannot see past. This would limit our observations to a "visible" universe which may be far smaller than what the "actual" universe may be. Alan Guth guesses that actual universe may of 25 orders of magnitude larger than the visible universe. While in principle this makes sense, what does not make sense to me is how there are galaxies that we cannot see because they are outside of some horizon, but for some reason we can see the light from the decoupling/surface of last scattering event. It seems to me that this surface of last scattering would have been receding away from us for far longer than the formation of galaxies which would have formed far after that event. Why doesn't the surface of last scattering lie outside the event horizon? I couldn't even seem to gain any insight on this after reading this article:https://en.wikipedia.org/wiki/Observable_universe What am I missing here?