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Light behavior in a black hole

  1. Jun 27, 2015 #1
    Good morning everyone, I'm Giuliano and I would like to know how light behaves in a black hole and because it can not get out.
    More precisely, i understand that light moves in curved space-time format from the black hole, but once passed within swarzchild radius the photon is expected to impact the superdense mass of the black hole , or can not get out because it does not have enough energy to climb the spacetime curvature and ends up to " stretch " within he has no more energy.
    sorry for my ignorance and for my english and thanks in advance.
  2. jcsd
  3. Jun 27, 2015 #2
    If a light beam goes into a black hole it can never go out.What happens to it.The photon energy increases the mass of black hole.Every energy fallen into blak hole makes it heavier.
  4. Jun 27, 2015 #3


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    Don't understand what you mean here.
  5. Jun 27, 2015 #4
    i mean that its wavelength would be lengthened
  6. Jun 27, 2015 #5


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    OK, but what's with the "no more energy" ?

    As a beam of light approaches a black hole, it becomes blue shifted from the point of view of someone closer to the black hole and I suppose that process continues past the event horizon, but I don't see the energy going to zero.
  7. Jun 27, 2015 #6
    thank you for your answer,
    As i know photons becomes blue shifted when they enter in the black hole and a red shift when they try to escape from it .
    A photon that was born exactly on the horizon of events , directed towards the outside of the black hole , would suffer an infinite red shift so its wavelength would be lengthened to infinite (his energy would become zero ) .
    Sorry for my english again..
  8. Jun 27, 2015 #7


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  9. Jun 27, 2015 #8
    I agree, but although we can not see the actual redshift of light , we can still take the redshift and the stretching of the wavelength as due to lack of leakage of light from a black hole ?
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