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Question on Hawking Radiation

  1. Nov 12, 2006 #1
    If black hole is so powerful, why doesn't it suck in Hawking radiation as well. I mean, it is just an electromagnetic radiation like light, right?
     
    Last edited: Nov 12, 2006
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  3. Nov 12, 2006 #2

    LURCH

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    Yes, it is just ordinary radiation (EM). However, the nature of the model that proposes the existance of this phenominon is that the radiation is generated just outside the event horizon of the black hole, at precisely the distance form which the escape of EM radiation becomes possible. Therefore, it escapes the area of the black hole and travels outward inhto space.
     
  4. Nov 12, 2006 #3
    To my knowledge, Hawking radiation are escaping virtual particles. When vacuum fluctuations appear near a black hole, sometimes, one particle will be near enough to the Event horizon and will fall in, while the other (just far enough away from the event horizon) could escape. This phenomenon is associated with the geometry of the virtual particles' "appearance" and the orientation they appear in when next to a black hole.
     
  5. Nov 12, 2006 #4
    If a particle-antiparticle pair were created from fluctuations in the external electromagnetic field, even if the antiparticle falls in it should only increase the contained mass-energy. Can someone elaborate on the explanation?
     
  6. Nov 13, 2006 #5

    George Jones

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    I wrote a bit about this in another post, and, more importantly I also gave a good link.
     
  7. Nov 13, 2006 #6

    hellfire

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    How does this explanation deal with the infinite time dilation for infalling objects observed by a remote observer?
     
    Last edited: Nov 13, 2006
  8. Nov 13, 2006 #7
    I love how Hawking explains how he came up with the idea -- Going to bed and he realized BHs have edges! I can't say I think the same way when I am that tired.
     
  9. Nov 13, 2006 #8

    Wallace

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    Infinite time dilation only occurs at the event horizon. Since Hawking radiation originates just outside of the horizon it does not experience infinite time dilation. If it did it would be unable to escape the black hole and wouldn't be called 'radiation'.
     
  10. Nov 15, 2006 #9

    George Jones

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    This explanation doesn't serve as a replacement for an actual calculation.

    This notwithstanding, you have raised a very good point, and I'm not sure that the dust for this issue has completely settled.

    I think various schemes have been put forward for why this is not a problem. Try looking for "transplanckian": using google; on the arxiv.
     
  11. Nov 16, 2006 #10

    Chronos

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    Hawking radiation arises from the pure statistics of virtual particles popping in and out of existence at the event horizon. At least a few of them inevitably escape the maelstrom. This a very subtle way through which black holes obey the laws of thermodynamics - there is no free lunch. Black holes are nearly, but not quite immortal.
     
    Last edited: Nov 16, 2006
  12. Nov 16, 2006 #11

    hellfire

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    I wonder if it is really possible to compute Hawking radiation in that way. For example, how do you calculate the rate of created / annihilated virtual particles per unit volume and time? From what I know about QFT you can compute probabilities, for example for the transition <0|0>. Calculating this you will only see what virtual processes contribute to this transition, but not the number density of them.
     
  13. Nov 17, 2006 #12

    Chronos

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    I have a biological analogy in mind - an amnionic membrane. A cell manages to preserve salinity by selectively permitting sodium ions to pass. The boundary layer of a black hole [event horizon] mimics this behavior.
     
  14. Nov 19, 2006 #13
    Let's say that a particlepair formed in "empty space", and that one of the particles was sucked in. What you are actually trying to say is that the particles obviously only passing by our roomtime, gets almost total room vector instead of whatever vector it had before, the thesis is that if the particles are lined, the outer particle might catch up with the inner particle, and if they collide, the photons they emit can escape the black hole. But since charged particles don't need room vektors to be able to emit energy, but a non roomly vektor that cut our room axis, that wont happen. But if you were talking about very small particles that through heisenbergs relations happened to escape the black hole, because with the roomvektor it achieved in almost being sucked in, can excape through heisenbergs relations, then it is impossible for the particle to stay in our universe for a longer time, since it can only get total roomvektor, if it is on the radius, and if it is on the radius, it cannot escape.

    That is my oppinion, and I am entitled to express a such.
     
  15. Nov 19, 2006 #14

    Labguy

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    I have posted this before but it fits well here too.
     
    Last edited: Nov 19, 2006
  16. Nov 19, 2006 #15
    So the time dimension is simply in a black hole, spatial, since particles cannot move in the speed of light along the time line. As soon as a particle is exposed of total acceleration, all dimensions are equally spatial, but the heisenberg relations still remains and thereby a particle at the event radius can move backwards in time and thereby temporarily repulse the black hole and leave it. But since gravity is a force that is not dependent of vectors, since a black hole have none, but rather time distance, and therefor it is probable that the cosmological constant attract these days, and that masses attract eachother because of their time distance. So the only way mass can really dissapear in the black hole (except colliding along the time line one particle at a time depending on where they are along it) is if the heisenberg relations makes time move backwards, or if time in empty space moves forward.

    That is my oppinion, and I am entitled to express a such.
     
    Last edited: Nov 19, 2006
  17. Jan 2, 2007 #16
    We can also say that how gamma rays emited ewen if light cannot escape from black hole? we can answer simpily Saying that gamma rays travel perpendicular to space time continummnot on it as light does.
     
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