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Observation of a black hole

  1. Apr 16, 2008 #1
    I just cannot understand the rationale behind the fact that whatever object we see 'enter' a black hole will appear to slow down to infinity next to the event horizon and never quite cross it. Would we not observe old black holes with a myriad of objects hanging around near it that it has captured over the billions of years?

    Since we never observe objects enter a black hole, does that then mean the mass of the black hole does not increase in our reference frame? However the idea that mass is relative I think is incorrect. (If energy is relative, energy is not conserved?)

    And hypothetically our universe collapses in 10 billion years. Would we not observe the matter finally collapsing into the singularity or will everything appear to stop still before the singularity of the big bang.
  2. jcsd
  3. Apr 16, 2008 #2
    I don't sure that I clearly understand your question, but I'll try my best

    We never see an object cross an event horizon because when we consider time coordinate of that object in a frame far from black hole , we found that time coordinate will approach infinity when an object move nearly horizon.

    and when that object reach horizon because it lie in a strong gravitational field so any EM radiation from it will be red shift until it wavelength are in the range that human eyes cannot detect. So if we look for an old blackhole we cannot see an object hang around it.

    others question I don't know the answer too :P
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