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Black Holes

  1. Apr 11, 2013 #1
    Hi, I'm at high school at the moment and i have gotten really interested in black holes and the way they work as i have been reading books from Stephen Hawking.

    So we know that black holes absorb matter and photons by the pull of gravity. And we also know that it emmits radiation. But because photons cant escape the pull and radiation can, does that mean the radiation should be travelling faster than the speed of light? It says that for something to escape a black hole it should be travelling faster than the speed of light. However this is incompatible with einsteins theory of relativity because he says that nothing can exceed the limit of the speed of light. Could the uncertainty principle make this possible?
  2. jcsd
  3. Apr 11, 2013 #2
    Photons are radiation. The radiation that "escapes" a black hole is a special kind called Hawking radiation. He says that it is hard to explain. So I don't even try to understand it.
  4. Apr 11, 2013 #3
    This doesn't really answer my question though because your telling me about this special hawking radiation (i know the name anyway) i asked if the radiation escaping could be faster than the speed of light.
  5. Apr 11, 2013 #4


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    Hawking radiation does not enter the event horizon but is created at it. It doesn't travel faster than the speed of light. It's creation is something to do with virtual particles becoming real I think but this is outside my field. Hopefully someone more informed can help you with a more thorough answer.
  6. Apr 11, 2013 #5


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    Light = electromanetic radiation = photons. They're the same thing.
    You're asking if light can travel faster than light.

    Hawking radiation(so, photons) is emitted from above the event horizon, so it does not violate the speed limit.
  7. Apr 11, 2013 #6
  8. Apr 16, 2013 #7
    By virtual particles, do you mean particle pairs that annihilate each other?
  9. Apr 16, 2013 #8
    yes Hawking radiation is a form of virtual particle pair production that occurs outside the EH. One of the pairs falls into the EH, the other acts as a blackbody temperature.

    this thread contains some information on Hawking radiation including when Hawking radiation takes effect as it only occurs during specific conditions discussed in this thread.


    this site contains some info on Hawking radiation


    here is a pdf copy of Hawkings paper


    another interesting aticle is this one

    edit I should be more precise here Blackhole evaperation only occurs under certain conditions.
    Last edited: Apr 16, 2013
  10. Apr 29, 2013 #9
    I'm not sure if this is relevant to this topic yet,
    I have not read it but i plan on it later today but,
    in sky and telescope there's an article,

    sky and telescope magazine
    june 2013
    " when black holes eat stars "

    I have a direct link to the digital magazine article if wanted.
    just let me know.
  11. Apr 29, 2013 #10
    Yes please :)
  12. Apr 29, 2013 #11
    I'm a subscriber to the magazine,so let me know if you can not access this, i tested it, it works, but i'm not sure if it is because i'm a subscriber, so let me know if it does or doesn't work.

  13. Apr 29, 2013 #12
    It doesn't work but thanks anyway :)
  14. Apr 29, 2013 #13
    hmm.. i'll try to find another posting about it..
    the only other thing i can suggest is, maybe go to the grocery store and find the magazine on the self and read it from there..
    but i'm not sure if it is out on stands yet...

  15. Apr 29, 2013 #14
    Im a subscriber to all about space magazine. Thats how i came about black holes and other stuff
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