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Thinking outside the box

  1. Feb 27, 2015 #1
    All that is visible to the human eye is that which can be seen at the furthest limits of the Cosmos, which began with the Big Bang. So then, what could exist from that point on? What space or material is the expanding Universe encroaching into, and either pushing it away, or transforming it into something else? I know the best answer is probably Space, but could it be something else? Some kind of Plasma or something.
  2. jcsd
  3. Feb 27, 2015 #2


    Staff: Mentor

    Welcome to PF!

    The short answer is we don't know.

    You can read more about it here:


    The expansion notion though is more like being on the 2D surface of a balloon and as the balloon expands distances between points on the balloon surface increase. We can't say the universe is expanding into anything, its simply that the distances between objects in the universe are increasing at an ever faster rate.
  4. Feb 27, 2015 #3


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    Staff: Mentor

    This thread has been moved into the Cosmology forum, as that is a better fit for this topic we're more likely to find a knowledgeable expert there.

    @johnveets you may want to search the cosmology forum for some of the other threads on what the big bang was and wasn't, and how the expansion of space-time works. The sticky "on the same page" thread at the top of this forum would be a good place to start.
  5. Feb 27, 2015 #4
    For the moment they are expanding ever faster, could still be the early stages of the Cosmos. Am thinking though in terms of science fiction and applying the laws of expansion and contraction. When items cool they contract, and when heated expand. Lets say at one point before the birth of our Cosmos, the former Cosmos decreased in size into something infinitesimally small due to cooling and gravity. Gravity would continue to crush everything into the size of who knows what. What would then trigger another big bang? What force would be able to do that? As the Cosmos collapsed, then the force outside of the Cosmos (which we have no idea what it may be, and cannot see)? Would grow in size? The big bang would somehow trigger having the opposite effect. Expansion, and creation would then be reborn? Wouldn't this notion leave creation and contraction(destruction) in perfect balance?

    [Mentor's note: Edited to remove a reply to a post that was moved to another thread: https://www.physicsforums.com/threads/questions-about-the-big-bang.800352/] [Broken]
    Last edited by a moderator: May 7, 2017
  6. Feb 27, 2015 #5


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    Staff: Mentor

    The universe is more like a gas. If you take a volume of gas and then allow it to expand into a greater volume, the temperature of the gas decreases. The universe works similarly. This is less apparent in the present universe, but the very early universe consisted of a high-density plasma which cooled as it expanded until it was cool enough to form a gas of hydrogen and helium (along with a trace amount of a few other elements).

    Any talk of something 'outside the universe' is beyond the scope of science, so we can't even begin to answer it.
  7. Feb 28, 2015 #6
    Very well, thanks for your time.
  8. Mar 3, 2015 #7
    That is the thing, the universe has no edge!!
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