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2nd event horizon in black holes!

  1. Sep 10, 2012 #1
    I recently saw a video where it was stated that black holes may have an inner 2nd event horizon where beyond it is trapped light and energy! I have searched the web for an explanation pertinent to this hypothesis but found nothing.

    Can anyone shed some light (if possible)?
  2. jcsd
  3. Sep 10, 2012 #2


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    That was discussed on a thread here recently but it was all deleted by the mods because it's nonsense. TV physics is very entertaining but often just nonsense.
  4. Sep 10, 2012 #3
    I will accept that is is nonsense since you say so and I have no reason to doubt you. I gather that contemporary understanding of Black holes gives us the ability to dismiss some hypotheses without hesitation?
  5. Sep 10, 2012 #4


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    I didn't see the video, so I can't say exactly what yours was about. However did you look up the Wikipedia for "Rotating black holes" and "Kerr metric"?

    I suppose that a black hole can have several interesting horizons or surfaces, if it is either rotating or electrically charged.

    You could also do a google search with keywords like "Reissner-Nordstrom" or "Kerr-Newman". It might be educational, or give you a better idea what the people in the video were talking about.

    Personally I don't think there will be any reliable answer or consensus about interior of black holes until there is an accepted quantum theory of their geometry. But it is good to know something about the existing classical (i.e. non-quantum) models of BH. You are right to keep asking questions, also to remain skeptical.
  6. Sep 10, 2012 #5


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    Maybe this post from George Jones is relevant: https://www.physicsforums.com/showpost.php?p=1973806&postcount=3.

    "(Non-extremal) Rotating black holes have two horizons. The outer horizon, the boundary of the black hole, is an event horizon, and nothing too special happens as an observer crosses this horizon. The inner horizon is a Cauchy horizon, and some calculations indicate that measured energy density diverges at the Cauchy horizon."
  7. Sep 10, 2012 #6
    Thank you all for the information. I will check it out. Lastly I really would appreciate it if phrases such as "its Nonsense" be kept out of my posts as they offer nothing and not forgetting that science requires us to be not only inquisitive but also sceptical too!

    Thanks guys!
  8. Sep 10, 2012 #7


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  9. Sep 10, 2012 #8
    Charged non-rotating black holes also have two horizons as long as the charge is sufficiently small. If the charge is sufficiently large one can obtain a naked singularity. However there is a conjecture that these cannot exist. As for the charged black hole this makes sense because a super-charged piece of matter would have a great electro-static repulsion force and would unlikely become a black hole.
  10. Sep 11, 2012 #9
    A very interesting read indeed. Thanks!
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