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Schwarzschild radius

  1. Aug 1, 2004 #1
    if schwarzschild radius is a pt. at which no information can come back after going in. Then what is Hawking radiation?
     
  2. jcsd
  3. Aug 1, 2004 #2

    chroot

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    The Schwarzschild radius is the locus of points at which the escape velocity of a mass is equal to c.

    Hawking radiation is thermal radiation emitted by a black hole. Microsopically, virtual particle pairs are forming in the space near the event horizon, as they form anywhere else in space. Sometimes, one of the particles crosses the event horizon, while the other escapes. The net result looks as if the black hole emitted a particle and lost mass.

    - Warren
     
  4. Aug 1, 2004 #3
    thanx chroot, few question.

    So the black hole doesn't emit radiation it's just the absence of the antiparticle that the particle come into view and can be seen, but tricks us because we think it just came out of the black void but it didint. am i right?

    Second if a particle is connected to antiparticle and it comes close to a black hole how can it get ripped away from its antiparticle and only it fall into the black hole, wouldnt the grip be too strong for anything to escape, how can the half be sucked in and the other half run away, sounds like if it could happen it would be a one in a million shot.
     
  5. Aug 1, 2004 #4

    chroot

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    Right. No particles can ever cross the event horizon from the inside to the outside. The particles that comprise Hawking radiation do NOT come from within the black hole, only from the region very close to the event horizon.

    Effectively, virtual particle pairs "borrow" energy from the universe when they are created. They "return" that energy when they annihilate. In the case of Hawking radiation, however, they never re-unite. The net result is that the black hole has given up some of its energy to allow the escaped particle to exist indefinitely -- to balance the universe's energy books, so to speak.
    Virtual particle pairs have to have zero initial momentum when they are created. In other words, they have to be going exactly opposite directions. In a region very close to the event horizon, it happens quite regularly that one falls right in, and the other flies right off. I don't know the exact number of such events per unit time per unit surface area, but it should be easy to calculate. If you'd like me to show you such a calculation, let me know and I will look into it. Even if it's a "one in a million shot," it happens often enough to be significant.

    - Warren
     
  6. Aug 1, 2004 #5
    yes yes please

    If it's not a bother can you show me.

    I would greatly be appreciative.

    also,
    I know i'm not to quick in this but can you restate the underlined part also, I see that law of conservation of mass/energy is broken, but then somehow its not. How does that work.
     
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