Could we ever detect other universes? © Getty Images

What is the Universe expanding into?

Well that depends if it's infinite or not.

Asked by:  Toby Graham, Shrewsbury

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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.

How do we know the Universe hasn’t always existed? © Getty Images

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