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Outside of Space

  1. Jul 1, 2010 #1
    recently ive been thinking about whats outside of space. And this thought really relies on the big bang theory. this is because in it it claims the universe is expanding so i wondered if its expanding then whats outside of it? And would it be the end of space or everything, what would exist there and how? if anyone could reply it would help accelerate my thoughts about this.
     
  2. jcsd
  3. Jul 1, 2010 #2

    russ_watters

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    Staff: Mentor

    Nothing is required for space to be expanding into.
     
  4. Jul 1, 2010 #3
    if nothings required then what is thats not space?
     
  5. Jul 2, 2010 #4
    You can't ask a Metaphysical question in a Physics context.

    This thread should be deleted
     
  6. Jul 2, 2010 #5
    I don't blame you for not understanding. Honestly I used to think the same thing. Perhaps the best answer is that when we say the universe is expanding, we mean that the space itself is expanding. We do not mean that matter is simply getting further apart. This expansion of space physically manifests itself as sort of expansion pressure. Of course it's only noticeable at very large scales, what we call the "cosmological" scale.

    And perhaps the best analogy is the balloon analogy. As a balloon expands, the space between two points will increase. Obviously the analogy isn't perfect because the balloon is expanding into something else. But the increase in the space between points isn't due to this, rather it's due to the stretching of the rubber. The expansion of space is sort of the same way.

    Anyway, hopefully that was helpful.
     
  7. Jul 2, 2010 #6
    I feel your pain. What's beyond the known, expanding, universe of stars, quasars, etc..?
    Is it "emptiness" forever?
    Some say that everything expands, time and space itself. Expands into what? What is it expanding into? The result is, obviously, 3-dimensions at least, so there is no end?
    To answer such questions is beyond my feeble mind.
     
  8. Jul 2, 2010 #7
    A proposed answer based on the curvature of space is that, if you travel in a straight line, and you go far enough, then you come back to your starting point, coming from the opposite direction. That's a way that space can be finite even though it has no boundary. Therefore the expansion of space means an increase in the distance for a straight line to return to the same point. This is analogous to a circular path on the surface of a sphere, but one dimension higher.
     
  9. Jul 3, 2010 #8

    russ_watters

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    "nothing" is not a thing. You can't argue your way out of reality with word games.
     
  10. Jul 5, 2010 #9

    mheslep

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    Heh, though many have tried.
     
  11. May 12, 2011 #10
    Redthinker, not everyone takes AJB's line on this. It is a legitimate question that needs an answer. In terms of the space that we exist in, it is, as others have said, "finite and unbounded", so that there is none of that kind of stuff "on the outside". However, there is a cosmology (called quantum loop gravity-based black hole cosmology) "invented" by Lee Smolin a couple of decades ago, that posits that the space we measure was generated as "linked loops" in a hyperspace continuum. We cannot step out of our loops of space, because all the particles that make us (and everything else in our universe) are simply excitations of those loops.
    In short, the universe only has a centre, edge, or "outside" in that hyperspace. Of course, this answer depends on the validity of LQG, which has long been criticised as "not connecting with experiment". However, it does provide an intellectual framework for understanding such bizarre effects as "inflation", dark energy (which does not behave the way it is supposed to on the basis of classical GR), etc.

    PS, I know this is a bit late, but I have only just found this thread.
     
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