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I realise that the universe is expanding, but doesn't it need more space to expand into? Is there some space outside our universe where the universe can expand? But if there is, doesn't it prove that the universe is not the whole thing? In fact, nothing can be because, according to our knowledge, everything is expanding.


marked as duplicate by John Rennie, ACuriousMind, Qmechanic Jun 8 '16 at 19:59

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  • $\begingroup$ There is no space "outside" of the universe, at least none that we know of or that we would need to describe it. What you see (when you look at the night sky) is all there is. $\endgroup$ – CuriousOne Jun 8 '16 at 14:32
  • $\begingroup$ Unfortunately, the same logic of expansion of, say a balloon, isn't applicable to the universe. We can't treat the universe as a 3D balloon that has known boundaries, since we don't know of the boundaries, if any, of the universe. $\endgroup$ – obliv Jun 8 '16 at 14:37
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    $\begingroup$ I personally don't think of space as a container, box or distance related "thing".....I think of it as the relationship between objects, and it has no meaning without the objects. $\endgroup$ – user108787 Jun 8 '16 at 14:37
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    $\begingroup$ Possible duplicate of If the universe is expanding, what is it expanding into? $\endgroup$ – John Rennie Jun 8 '16 at 14:45
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    $\begingroup$ See also: Did the Big Bang happen at a point? (it didn't!) $\endgroup$ – John Rennie Jun 8 '16 at 14:45

The universe, by definition, is all there is. So there is nothing outside it, not even space, since if you extrapolate the present expansion of the universe back far enough in time, you end up with a tiny space, just after the big bang occurred.

So, from a personal perspective, I ignore the ordinary definition of the word space, as in the "space between New York and Washington". That's OK for small distances, but on the scale of the universe, which is what your question is about, I would prefer to think of space (actually spacetime) as a record of the relationship between the physical objects within the universe.

I am not sure this is a view widely shared, as it could be seen as a way out of answering your question, however it it is the only way I can think of to address it, whilst keeping in mind that the universe is ALL there is, including spacetime.

After all, what actually is " Space". It's nothing, no thing, so you can have some leeway in your definition of it :)


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