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Big Bang and PreExisting Void?

  1. Aug 31, 2010 #1
    How do we know that the Big Bang did not expand into a preexisting void?

    What is the justification for this knowledge/belief?
  2. jcsd
  3. Aug 31, 2010 #2
    The BB didn't expand "into" anything (in the way you're suggesting). Space(-time) itself is what was expanding, not just the matter in it. It doesn't make sense to describe it as expanding "into" something.
  4. Sep 1, 2010 #3


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    If you examine what a universe would look like "from the outside", so to speak, it would look like a black hole. Because the new universe looks like a black hole from the outside, it is unable to expand into the pre-existing universe. But it has no trouble expanding from the perspective of somebody within the new universe.

    That is, if a new universe was generated from a vacuum fluctuation in an existing universe, it would look like a microscopic black hole that came into existence for a moment, then rapidly evaporated away. One way of looking at it is that the space-time of the new universe "pinches off" from the old one, and almost instantly the new universe is all on its own, with no connection to where it came from.
  5. Sep 2, 2010 #4


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    Painting on a canvas is a classical argument - suggesting matter must be superimposed over a preexisting 'space'. There is no valid theoretical or observational evidence supporting that premise.
  6. Sep 2, 2010 #5
    lets assume that it did expand into a preexisting space. Then where did that space come from? Another Big Bang? Did that Big Bang expand into a preexisting space?

    At some point there had to be a Big Bang that created space itself.
  7. Sep 2, 2010 #6
    If cold is the absence of heat, and dark is the absence of light, why can’t an infinite and eternal space be the absence of matter? To me asking the question where did space come from doesn’t make any more sense than asking where did dark or cold come from. There does not seem to be consensus on this forum as to whether space existed prior to or was created by the bb.

    Okay…back to lurk mode for me.

  8. Sep 2, 2010 #7
    infinite and eternal space of how many dimensions? 3? why not 1,826,548,356,657 dimensions?
    Last edited: Sep 2, 2010
  9. Sep 2, 2010 #8
    And it still may safely be assumed that no information could 'pass' through the Big Bang event. i.e. No matter formation 'instructions' at any scale level, or anything else. Everything that took place after has just been random chance out of perhaps a near infinite range of possibilities?
  10. Sep 2, 2010 #9
    well, the big bang itself seems to over-ride a fundamental law in biology where spontaneous generation (eg- a universe [XD]) is impossible, unless being that there can be apparently be another creating force to do it.

    Also in statement, having an infante number of dementions seems to sasify this as well, as in an infante number of universes may have existed previously. Furthering that, with an infante number of dementions, there could be an infante number of different results in each of the other universes created from other "big bangs" occuring in other dementions. Furthering that, having an infante number of dementions with universes ending to an infantle variable rate they'd be destroyied/created.

    ..the big-bang was technically random?

    Or can alternate dementions interact? For example, if universe "A" was being destroyed. While inside universe "A" another random universe was being created. (having an infante number of detementions within a demention) Due to the fact a universe may be random. Now, this new "internal" universe, universe "B" was expanding and universe "A" was being destrioed. Apon Universe "A"'s destruction, universe "B" was able to form fully. Any such that was aware of universe "B" was able to excape to it. And any such unaware of universe "B" was destroied.

    (why does this sound like economics, cancer, and the molting of an animals skin.....?)

    Now in this example, there is only now universe "B" but all the such lone in the destruction of universe "A", does this mean the remniants create a NEW universe??? Kinda like the "seeds" of a tree that was chopped down.

    o_O... (why does this sound religious, philosophical, and strangely like the book "the lord of the flies"...?)

    And due to the fact these lone such are in hyper space, they can expand without any other universe holding them back by those universes forces.

    Last edited: Sep 2, 2010
  11. Sep 3, 2010 #10
    Getting back to this for a moment, could it not be that a void surrounded the BB which was not comprised of spacetime but rather was a simple void which had no characteristics or properties? Could multiple universes be "housed", surrounded in a void soup of sorts? It outwardly seems to me that the existance of a void of this sort could never be proven or disproven.

    I love this thread, very interesting!
  12. Sep 3, 2010 #11
    In such case there should be a border between 'ordinary' and how you call it 'simple' void. You would face many difficult questions like:

    Why both types of void have the same number of dimensions?
    What happens in places where ordinary space is curved?
    What is a border between 2 types of voids?
    Is it sharp or smooth?
    What happens to an object or particle going thru the edge?
    In any case, go thru all theories (QM, EM, Gravity) and incorporate such type of object there.

    Purely hypotetically, if our spacetime could have edges in space, such edges would emit enourmous quantities of hawking radiation because of the pair production, when 1 component of the pair dissapears behind the edge. Contrary to Black Holes, that radiation is not redshifted by gravity and is EXTREMELY intense. Very soon it curves space because of its enourmous energy density and creates real black hole with a 'normal' event horizon :)
  13. Sep 3, 2010 #12
    We don't.

    We can however say that the observations of the universe are inconsistent with any void existing any part of the universe we can observe or which influences the behavior of anything that we can observe.
  14. Sep 3, 2010 #13
    Let me rephase that to something stronger. The observations say that for the parts of the universe we have any data of, that the universe is not spreading into a void. If the universe was spreading into a void, you'd see the effects of the void. You don't.
  15. Sep 3, 2010 #14
    Not true. Anytime someone "assumes" something, you should ask why we are assuming that.

    Some of the current work in cosmology is to work on models of what the universe might of looked like before cosmic inflation happened and to see if any of the "pre-inflation" universe could have any effect on observable things like the CMB power spectrum.

    This is important because relating theory to observations is what science is about.
  16. Sep 3, 2010 #15
    Dmitry67, thanks for your convincing reply, this stuff makes my brain hurt after 74 years of experience with edges and boundaries. One final idiot question:

    Assuming the existence of multiple universes for a moment, it appears that they cannot be separated from our universe by any sort of boundary, like a border fence. Do they then co-exist within our own universe, separated from us by different dimensions or time? If our universe is infinite/flat, where else could they be? (Brain hurts again.)
  17. Sep 3, 2010 #16
    Oldfart, our universes our 4 dimensional, so they can coexist in higher dimensional space without any intersections. That hypotetical super-space is called BULK. However, lets wait for TOE to get clearer picture.

    For the classification of types Universes in Multiverse (I, II, II and IV) google Max Tegmark Mathematical Universe Hypotesis.
  18. Sep 3, 2010 #17
    Thanks again, Dmitry67! I checked some of Max's stuff, did not understand it, but then, what's new? Is there a book or two out there that sort of gently leads a layman by the hand through our infinite, expanding universe? You can see by inquiries in this thread that some of us have conceptual problems, need help. (Though I fear that the math involved may greatly limit communication between us.)
  19. Sep 3, 2010 #18
    What effects would a void have? Wouldn't said void, by definition, be empty of anything that would cause an effect that could be detected?
  20. Sep 5, 2010 #19


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    There is a word they use in physics for anything that is entirely uninteractive - nonexistent.
  21. Sep 5, 2010 #20
    Dang, Chronos, I've spent at least ten minutes trying to figure out whether your statement is helpful or simple sarcasm...

    OK, lets see if I've got this figured out. Assuming the universe is flat/infinite, it didn't just get infinite one day but always has been, even at the start of the BB, when it was, lets say, the size of a pea. Correct? OK, us folks that have this mental picture of the BB expanding into a void are mentally sitting in this void, outside the BB, and watching this thingy expand, and thinking yep, it's expanding into a void, alright! But this cannot be a correct way of thinking, as this would mean placing the observer beyond infinity. The observer, and the void for that matter, cannot possibly exist beyond infinity. Correct?

    Having made the void impossible, I am now left with only the minor mental problem of stuffing an infinite universe into a pea...
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