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Can a Black Hole create Supernova?

  1. Jul 12, 2005 #1
    Can a Black Hole create Supernova???

    Is it possible that a Black Hole gets too big, and then just explodes under the pressure of it's own mass. Like a balloon that explodes because we blow it to much. Is it possible that a Black Hole can have a critical mass at which it simply explodes? :confused:
     
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  3. Jul 12, 2005 #2
    You may be interested in the following articles:
    http://en.wikipedia.org/wiki/Stellar_evolution
    http://en.wikipedia.org/wiki/Supernova

    A black hole is characteristic for having a radius smaller than it's event horizon. Any matter coming into the black hole could not escape it. Black holes however can "evaporate" through a process known as Hawking radiation.

    More mass means stronger gravity. Gravity pulls inward.
     
  4. Jul 12, 2005 #3

    Janus

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    Just one additional point. As the black hole gets more massive, the rate of evaporation via Hawking radiation slows.
     
  5. Jul 12, 2005 #4
    So the black holes are growing infinitely??? Are they going to consume all universe?
     
  6. Jul 12, 2005 #5
    They won't comsume all the universe, they can continue to feed as long as the have a "food" supply.
     
  7. Jul 12, 2005 #6
    That's kind of contradictory, isnt it?

    If they go untill there is no more "food", how can they NOT consume the entire universe, the universe being made up entirely of "food", or matter?
     
  8. Jul 12, 2005 #7

    Janus

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    To be more correct they will continue to grow as long as the "food supply" exceeds the rate at which they evaporate through Hawking Radiation. As the Universe expands, it cools and the matter distribution thins out. Given enough time, the incoming radiation and matter for even the largest black hole will be less than it emits in Hawking radiation and it will start to shrink.
     
  9. Jul 12, 2005 #8

    Danger

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    You might perhaps be making the common mistake of thinking that a black hole's gravitational influence is vastly greater than that of another, larger body of similar mass. It isn't. If a star of 4 solar masses collapses into a black hole, its gravity is still the same as that of a 4SM star. The field is just incredibly compressed as you approach because you can get so much closer to the centre of mass. For instance, if our sun were to be non-violently reduced to a black hole, the planets would all remain in the same orbits that they have now. The gravitational influence only extends when infalling matter increases the mass.
     
  10. Jul 12, 2005 #9
    Ahh... Hawking Radiation. Fascinating stuff. So am I correct in saying now that black holes cannot engulf the universe? Or can they, but it requires many of them, or perhaps one that evaporates at a very slow rate, maybe not even at all?
     
  11. Jul 12, 2005 #10
    Correct me If I'm wrong but if Hawking Radiation is happening, "stuff" actually escapes gravitational force of the Black Hole?!! So that means that it travels faster than light, contradicting the Theory of Relativity??
     
  12. Jul 14, 2005 #11
    General relativity says that Pressure/Density are also factors in Gravitational infulence of a massive body.This implies that, If our sun were to be some how non-violently reduced to a black hole, the Gravitational influence will be increased by a big factor and hence, Greater curvature of space ==> increase in angular mometum of planets around the event horizon . I honestly believe that the inner planets will eventually spiral-inn and the gaseous atmosphere of the gaseous giants would form the accretion disk...
     
  13. Jul 15, 2005 #12

    Chronos

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    Consider yourself corrected :smile: . Hawking radiation is a quantum effect. Relativity is not imperiled.
     
  14. Jul 15, 2005 #13
    To expand on Chronos' reply, nothing from inside escapes, it's just replaced by new stuff that's torn away from the fluctuating vacuum of empty space.
     
  15. Jul 15, 2005 #14
    Black holes that form from supernovae are very massive and therefore evaporate very slowly because the bigger a black hole is, the slower it radiates energy. To quote Stephen Hawking:

     
  16. Jul 15, 2005 #15
    Yes,but the Hawking radiation has never been proven.What's the point of discussing about black hole evaporation,if it has never been proven,only in mathematics?
    What if black holes last forever???Although,I personally think they should.
     
  17. Jul 15, 2005 #16

    pervect

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    The point of the discussion is to describe how current theory predicts black holes should act. This is how science advances - predictions are made according to a theory, then they are checked experimentally. It is important to have an actual theory that predicts results, and not to just have people making things up as they go along based on some sort of guess, gut feel, or other prejudice. Random guessing based on personal prejudices does not significantly advance science.

    The very short answer to the original question

    is simply "No, not according to general relativity". But that's not really much of a discussion, so people have very thoughtfully explained in much more depth.

    At the moment we are not in any position to check for the emission of Hawking radiation from black holes in the near future, though experiments have been proposed (but not yet carried out AFAIK) to check for a very similar effect known as Unruh radiation.
     
  18. Jul 16, 2005 #17

    Who's right on this? I think Yaaks is, but can someone reconfirm?
     
  19. Jul 16, 2005 #18

    Chronos

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    Yaaks is wrong. If you magically collapsed the sun into a black hole, it would have absolutely no effect on planetary orbits. Not even Mercury would so much as quiver.
     
    Last edited: Jul 16, 2005
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