(Feel free to correct any mistaken assumptions I have)
The overall question I have is: given that the early universe started as an incredibly dense ball of matter and energy, why didn't that mass stick together in one huge "blob" due to gravity instead of becoming, as it is, "homogeneous and isotropic"?
One explanation I can think of is that the universe is constantly expanding. But if the expansion rate in the early universe was sufficient to tear apart this hugely dense ball of matter which must have been undergoing massive gravity, and the expansion rate is constantly increasing, why doesn't that same expansion force continue to tear apart stars and planets today?
Another possible factor is that heat in the early universe must have also been large, and heat tends to push atoms apart (not sure if this is true of subatomic particles). If this is the fundamental reason, we would expect to see an equilibrium reached between the expansionary force of heat, and the contractionary force of gravity, and (I reason), the universe would be composed of one big "galaxy" instead of, as it is, many galaxies quite separated from each other.
So what is the explanation for the current structure of the universe? Thanks.