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Why does time stop in the event horizon of a blackhole?

  1. Feb 8, 2014 #1
    Why does time stop in the event horizon of a blackhole? Or at least slow down, from what i know.
     
  2. jcsd
  3. Feb 8, 2014 #2

    mathman

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    It depends on the reference frame. Something falling in experiences no effect on time. However a distant observer would see the object as slowing down and never quite falling in.

    The explnation is in the equations of General Relativity. (I am no expert).
     
  4. Feb 8, 2014 #3
    leonard susskind describes it pretty good on youtube classic mechanics lectures from stanford university really learned a lot from his lecture heavy into math if you ask me but he says it elementary math
     
  5. Feb 23, 2014 #4

    marcus

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    Dearly Missed

  6. Feb 24, 2014 #5
    Mr Marcus, the link given by you helped a lot. Please correct me if I am wrong: time does not actually decrease, but it appears to be slowed down due to red shift or blue shift.


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  7. Feb 24, 2014 #6

    Drakkith

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    Time dilation really does occur, it's not just a result of red shift.
     
  8. Feb 24, 2014 #7

    marcus

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    I think people can have different perspectives on appearance vs. reality, Manraj.

    Personally I consider gravitational time dilation to be absolutely real! And I consider it to be the same phenomenon as gravitational redshift.

    Deeper down clocks run slower, the evolution of physical states is slower, the atoms in the downstairs laser vibrate slower, so the light it makes is redder---all from the standpoint of the guy upstairs.

    The gravitational time dilation is what CAUSES the gravitational redshift. So both are actually real. That is just how I see it. Other people may have different ways to understand it.

    I can see no other explanation for the gravitational redshift. Can you?

    I think the way they experimentally TEST these gravitational effects is by sending light (or other electromagnetic signals) back and forth between "upstairs" and "downstairs" atomic clocks and other devices.
     
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