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Thread: Black Hole paradox.

  1. #1 Black Hole paradox. 
    New Member chairrex's Avatar
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    Dec 2007
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    Suppose a large-mass(~10^6 solar mass) black hole is considered. Here are the facts that we know:

    1. the radius of event horizon is large;
    2. the tidal force around event horizon is so low, comparable to tidal force on Earth;
    3. information cannot be sent inside event horizon to outside;
    4. escape velocity inside event horizon is larger than speed of light.

    So, when a person's head is staying at 0.75m outside event horizon with an engine tie to his/her head. The engine is trying to move away from black hole very close to speed of light/speed of light. The person's wrist is staying at event horizon and his/her leg is staying at 0.75m below event horizon. Now,

    1. the person cannot be killed due to tidal force, but can information in his/her leg reach his/her brain? If not, he will die because the lower body is essentially disconnected from upper body.

    2. the person cannot be disintegrated, but the head of the person can move away from black hole because it is situated outside event horizon. However, if the head can move away, the leg should move away from event horizon, otherwise the body is disintegrated. However, the person cannot be disintegrated based on the assumption(2) above. But the leg cannot move out! Because escape velocity is larger than speed of light. So can the person be evacuated from black hole?

    3. the mass of lower body is inside event horizon, so they are counted as mass of black hole. So when the lower body go inside event horizon, the mass of black hole increases a little bit. By theory, the radius increases such that the event horizon will expand outward. Can the viscious circle swallow up the person even if only a part of the person is below event horizon?

    4. why didn't scientist mention event horizon itself kills people, but tidal force kills people?

    5. based on the theory of Stephen Hawking, BHs shrink due to Hawking radiation, such that radius decreases. Suppose a body is strong enough to withstand tidal force and his/her leg is below event horizon initially. Then as the radius shrinks, his/her leg finally should comes out from event horizon. As the information recorded by his/her leg is organized, his/her legs can collect data from black hole before coming out from event horizon. After coming out from event horizon, other people in universe can know organized information from the person. This violates 2nd law of thermodynamics and assumption of Hawking.


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  3. #2  
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    Black Holes shrink at a ridiculously slow rate, only emitting the equivelent of an atom every now and then. So you're talking about a googol years for this to happen.

    Also won't the gravitational stress on the body cause it to be destroyed hence why you cannot get close to the hole in the first place?

    Barry


    Thinking of the question is greater than knowing the answer...
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