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How is the Big Bang producing singularity not a black hole?

  1. Jan 1, 2014 #1
    Hey, so I've been wondering about this question for a while and was wondering if anyone could support the Big Bang theory in this respect or anything else. Just wondering if anyone has an answer that might aid me in understanding this, thanks.
     
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  3. Jan 1, 2014 #2

    PeterDonis

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    I'm wondering why you would think the Big Bang is a black hole in the first place. A black hole is a region into which matter falls and can't escape; but matter comes *out* of the Big Bang.
     
  4. Jan 1, 2014 #3
    What I was confused about was this though: if the singularity that started the Big Bang is so infinitely dense, how did it not become a black hole?
     
  5. Jan 1, 2014 #4

    Drakkith

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    A 'singularity" means that our math has broken down and started given us nonsense for answers. You could say that we don't know enough about how physics works at that scale to avoid getting infinity as an answer. It is thought that future advances in our understanding of physics will lead to a black hole without a singularity.

    Also, the normal rules for black holes do not apply to the very early universe because it was dominated by spacetime expansion, whereas a regular black hole is not.
     
  6. Jan 1, 2014 #5

    phinds

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    You are misunderstanding the meaning of the term "singularity" AND you are misinformed about the density of the early universe.

    "Singularity" means "we don't know WHAT is going on because the math model breaks down". The big bang singularity and black hole singularities are not believed to be in any way related or similar, they are just both places where the respective math breaks down and so have the same generic name.

    The early universe (at about one Plank time) is not believed to have been infinitely dense, nor was it a point. It was a plasma of indeterminate size (possibly infinite in expanse) of a density and energy pretty much beyond human comprehension, but not infinite in anything other than possibly the expanse.
     
  7. Jan 1, 2014 #6

    phinds

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    Damn. Beat me by 2 minutes. Have you been taking speed typing lessons? :smile:
     
  8. Jan 2, 2014 #7

    PeterDonis

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    It actually wasn't infinitely dense, as other commenters have pointed out; but the more important point here is that, as Drakkith pointed out, the universe right after the Big Bang was expanding very fast, fast enough to overcome the attractive gravity of the matter and energy that was present; in other words, the matter and energy were flying apart too fast to collapse into a black hole.
     
  9. Jan 2, 2014 #8
    Ok, thank you very much all of you, this has all been really helpful.
     
  10. Jan 2, 2014 #9

    Chronos

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    Some theorists have posited gravity may be repulsive under conditions that existed at the time of the big bang, but, that explanation does not appear sufficient to explain superluminal expansion in the very early universe.
     
  11. Jan 2, 2014 #10
    also you need pre-existing space for a black hole to exist in.
     
  12. Jan 28, 2014 #11
    If it was infinite in expanse, would it not also be infinite in energy?
     
  13. Jan 28, 2014 #12
    If the universe is in fact infinite, then it would also have infinite mass/energy. If its finite then its energy content is also finite. We still do not know if the universe is infinite or finite. However if its infinite now then it was infinite in the past and vise versa
     
  14. Jan 28, 2014 #13
    It would not be a black whole because the energy used would combust not create a life killing wormhole



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  15. Jan 29, 2014 #14
    surely a black hole would only exist in pre-existing space. otherwise it would just be a "naked singularity". the descriptor "black hole" just describes the even horizon does it not?
     
  16. Jan 29, 2014 #15

    phinds

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    HUH ? What is a "life killing wormhole" ?
     
  17. Jan 29, 2014 #16

    Chronos

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    Yes, I like that idea. The big bang was a black hole in another universe and our universe is a white hole at the other end of the wormhole that resulted...
     
  18. Jan 29, 2014 #17
    I don't, a blackhole doesn't have consistent feeding rates, if we were part of the whitehole we should see variations in expansion rates due to variations in BH feeding rates
     
  19. Jan 29, 2014 #18
    Yes but the black whole would be very small and condense and would more than likely blow up
     
  20. Jan 29, 2014 #19
    Well I mean a black whole that would have killed all the living, if there where any, Homo sapiens.
     
  21. Jan 29, 2014 #20

    Drakkith

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    What are you talking about?
     
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