We're told that all matter in the universe is "expanding", presumably due to residual energy release created by the "big bang". But what (or perhaps more importantly "where") is the universe expanding into? I'm not approaching this from an astrophysical perspective, but from an ontological one. Namely, if all matter in the universe is expanding into the vacuous nothingness, and the universe is surrounded by nowhere, then how can something (the universe) exist in nothing and nowhere?
See here for some similar questions and their answers.