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I have understood that the universe is expanding at an accelerated rate. I have also thought, perhaps mistakenly, that this expansion means not that the masses in the universe are moving away from each other as in some explosion, but rather that the actual space was expanding and in so doing creating the illusion that masses were moving. This is also how I have understood the big bang. Is this correct, and if actual space is expanding, does not not also have to have an edge if as data show the universe is not looped on itself but rather flat?

Qmechanic
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  • The masses are moving. What you see is what you get in science, we don't discriminate between what one observes and what is considered "real". That's a difference that the philosophy department has been pondering without any success for the last 2500 years. There is no "edge" of the universe. It is either infinite or it is closed in some way, but the global shape is simply not testable, hence there is no need to even ask that question, at least not within science. In philosophy we are free to ponder the invisible for another 2500 years. – CuriousOne Jul 19 '16 at 14:42
  • The proposed explanation for each body moving away from one another is, indeed, the expansion of space itself. As curiousone said, there is no immediately obvious way in distinguishing the right interpretation. There is no compelling proof to have us believe the universe's expansion is finite or infinite. – Obliv Jul 19 '16 at 15:06
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    as in some explosion Can you imagine that there is no center to the universe, (because there isn't), if you can then you might get a better idea of the fact there is no edge either. Have a read of this: http://www.livescience.com/33646-universe-edge.html –  Jul 19 '16 at 15:06
  • Possible duplicates: https://physics.stackexchange.com/q/24017/2451 and links therein. – Qmechanic Jul 19 '16 at 17:31
  • @count_to_10 Actually, I'd argue that there is a geometric center to the arrangement of matter in both the early universe and now. The actual center of the global geometry of the universe, I think, is indeterminable as of now. – Obliv Jul 19 '16 at 17:55
  • @Obliv didn't Godel have an idea about a rotating universe, a good while back? From memory, part of the arguments against it was, so long Copernican Principle. I would like it to be true, that there was a centre, but I can't see how it fits with the Big Bang Theory. I don't think there is, or ever was, any special place in the universe. Regards –  Jul 19 '16 at 18:31
  • @count_to_10 Well whether you consider a center of something to be a 'special' place is irrelevant in this context. I don't see any reason why there cannot exist a center for the matter of the universe. Clearly by extrapolating time backwards through observation of redshifting bodies, we can deduce the approximate density of matter in the earlier universe. What rules out considering a center for this shape created by the arrangement of matter? – Obliv Jul 19 '16 at 18:39
  • Well, as far as I know, we can only see a certain indeterminate amount of the matter of the complete Universe , and I guess you are talking in principle only, but I'm sure we would agree that presently we don't have the data to work backwards. Personally, I kinda follow Smolin's argument, that on a cosmological scale the notion/definition of space is not distance, but rather how objects relate to each other. I'm a newbie to this, but John Rennie could give you a more coherent answer than my ramblings. –  Jul 19 '16 at 18:56

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