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End of a black hole

  1. Jan 20, 2005 #1
    a perhaps idiot question from a dummy : can a black hole become unstable ?
    Because I imagine the universe at it's origin had to be a super black hole comprising all matter. If there has been a big bang then that super black hole should have become unstable causing the bang
     
  2. jcsd
  3. Jan 20, 2005 #2

    GENIERE

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    I’m way over my head in this, but I would say a black hole can only exist within a universe, and the properties of each would be very different.
     
  4. Jan 20, 2005 #3

    Chronos

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    Hi piercas, welcome to PF. Ordinarily a black hole is quite stable once formed. Theoretically, they will all eventually evaporate, but the universe will be a long dead ember by the time that happens. Most theorists do not regard the universe as a whole to be, or have formed from a black hole. The mathematical description of the cosmic singularity [big bang] and gravitational singularities [black holes] are not the same. If, however, the universe is an inverted black hole, the big bang would have happened when that particular black hole formed in whatever spacetime region it resides.
     
  5. Jan 27, 2005 #4
    What do we know exactly about the origin of the universe and what do we mean by 'universe'. Is it the univse of matter ?What about 'before' the big bang. 'time' did not exist ? But that 'singularity' had to exist, 'had' including a factor time. Besides what is the definition of 'time'. Perhaps it's what is allowing us
    eventually to die.
     
  6. Feb 4, 2005 #5

    Nereid

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    Whoa, drinking from a firehose!

    'origin of the universe': depends on how iron-clad you like your science. IMHO, there is an absolute barrier ... the first Planck second; before that we cannot possibly have any f**ing clue (our two most successful, 'universal' theories - QFT and GR - are wildly inconsistent then, so how could we possibly have any confidence in any science-based answer?)

    'universe' is pretty simple; a) everything; b) everything that's encompassed by the domain of QFT+GR. Under the former, 'multiverses' make sense, and are (partially) amenable to science-based investigation; under the latter, anything beyond is no different from the labours of pottery magicians.

    'matter' (is all you need): from the first Planck second, yes (as long as you extend the definition of 'matter' to DM and DE)

    'before the Big Bang': the clouds that I see from the window of my study reveal, with crystal clarity, the spirits of the pets of my neighbours, friends, and relatives. The previous sentence has as much (scientific) validity as your question. Please do take the time to understand that 'before' (in this context) is as theory-laden as 'black holes have no hair'

    'time did not exist': see above.
    See above.

    'what is the definition of time?': I suggest that you spend some time reading a good book on GR; alternatively, you could read some philosophy. Either way, please decide if you are looking for something scientific (in which case we will continue our discussion here), or not (in which case I will gladly copy your posts into the relevant part of the Philosophy section of PF).
     
    Last edited: Feb 4, 2005
  7. Oct 1, 2007 #6
    I thought the universe's Big Bang was caused by a atom that blew up or something like that. Plus the Big Bang is only a theory
     
  8. Oct 1, 2007 #7

    cristo

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    Whoever gave you that idea?
    Correct. However, the hot big bang model is the best model we currently have and, whilst it has its downfalls, it explains a lot of observations that other theories cannot.
     
  9. Oct 8, 2007 #8

    Chronos

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    The BB hypothesis only holds water after the first few ticks of Planck time. That is a pretty impressive, albeit imperfect approximation. What preceded that 'time' remains unkown, and quite possibly unknowable.
     
  10. Oct 8, 2007 #9

    DaveC426913

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    Atoms are only theory too. Just because something is theory does not mean it should be qualified as "only".
     
  11. Oct 9, 2007 #10

    Chronos

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    Some theories are more robust than others. Nothing is absolute [a notion Einstein would likely endorse] - everything is theory. Separating the wheat from the chaff is the issue.
     
  12. Oct 11, 2007 #11

    H^w

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    Can somebody tell me what these two letter theories are?

    Do they have a name other then the two letters? I'm new to this space stuff, and am looking for more information, I tried using just the letters to find information; as of now Ive been less then successful...

    Thanks
     
  13. Oct 11, 2007 #12

    wolram

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    Dark energy, Dark matter, General relativity.
     
  14. Oct 12, 2007 #13

    H^w

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    Ah so simple.

    Thanks
     
  15. Oct 12, 2007 #14

    DaveC426913

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    Preponderance of evidence, Lack of competing theories.

    The Big Bang, while not a slam dunk in either department, is pretty far out in the lead.

    So we go with this theory unless there is a compelling reason to look elsewhere.
     
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