Asked by: Toby Graham, Shrewsbury
Presently we do not know (and may never know) whether the Universe is infinite or not. If the Universe is infinite, then it can simply keep expanding without getting any bigger (since you can’t get bigger than infinity). It’s therefore not expanding into anything. On the other hand, if the Universe is finite in extent, this question becomes impossible to answer, since – being part of the fabric of the Universe ourselves – we have no way of looking outside it.