Comment Re:Correct me if I'm wrong (Score 1) 162
you can think of our universe being defined by paths of light, after all that's what you would 'see' and they trace space like a pen on paper. They ride the curvature of space caused by gravity. Let's day hypothetically there was no more matter after a point (and no particles either). In this case gravity would cause that space to bend back on itself. In such a case you essentially cannot escape as you would curve back into the existing universe. Similar principles hold if the matter is too dense or to sparse, the universe essentially becomes a closed off bubble. Within our physical laws only a very specific and exact value of density will allow for space to extend forever. There simply isn't an outer boundary that can ever be reached, in any case of our physics, just one that can be seen - the initial forming of our space time itself.
there are internal boundaries, such as black hole horizons. We are understanding more and more about them. While we don't have the means to actually test at those energies (maybe the large hadron collider will spit out some miniature ones we will see) there has been a great deal of debate about exactly what particles, entanglement, forces and energies infalling matter experiences.