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Event horizons

  1. Apr 6, 2010 #1
    I am believing that event horizons refer to where light can no longer escape the gravity of a black hole. What about everything else that moves at less than the speed of light?
    If a small moon winked into existence at some point further out than the event horizon with momentum that was sending it away from the black hole (if you could believe such a thing), would it get sucked back into the black hole like light? Does matter get sucked in faster than photons of light? Is there a separate 'event horizon'-like distance where matter can either escape or fall back in?
  2. jcsd
  3. Apr 6, 2010 #2
    Ah. Just seen the black hole video.
  4. Apr 6, 2010 #3


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    ANY object within the EH will be unable to escape from the black hole. Things farther away than the EH may or may not go into the EH depending on initial velocity.
  5. Apr 8, 2010 #4
    With the moon, it would depend on it's initial velocity, like Matterwave noted, and the strength of the black hole. If the initial velocity is greater than the escape velocity, it's good to go. As for matter and photons, well matter has inertia, so you can naturally make conclusions off of that. There is only one event horizon, & beyond that, as far as we know, there is no hope of getting back out, except Hawking radiation.
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