If all matter was created in the Big Bang (not counting spontaneous generation of particle-antiparticle pairs), wouldn't that imply that a finite (if very large) amount of matter exists in the Universe?
By the same token, wouldn't that imply that the Universe is spatially "finite", i.e. a compact (if boundaryless) 3D manifold?
If not, why not?
All we really know is that all of the matter in the observable universe was a very uniform, very hot, expanding plasma about 13.7 billion years ago. We don't know where that came from. "Big bang" is just a name for our ignorance.
Whatever process produced that state could plausibly have produced a region of finite or infinite size. Whether it's finite or infinite, it could be just one part of a larger universe. At this point we just don't know.
