Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Black Hole Question

  1. Feb 26, 2009 #1
    I read that if an observer were to watch as another observer fell into the black hole, eventually observer A would see B stop before reaching the event horizon. I'm having a little trouble with this and have to questions about it.

    1)If we turned an extremely powerful telescope at a black hole, would we see all the matter that the black hole has pulled in frozen at the event horizon?

    2)When a star is collapsing to form a black hole, after enough mass has been compacted and a black hole has formed, then shouldn't whats left of the collapsing mass be frozen outside of the event horizon again? Making it seem as though it never colllapsed completely into a black hole, to an observer outside the event horizon?
  2. jcsd
  3. Feb 26, 2009 #2


    User Avatar
    Science Advisor

    The answer to both questions is yes. In fact (second question) to the outside observer the black hole never forms. However, the stuff that appears frozen will disappear from view over time, since there will be continual red shifting of the light from the stuff at the black hole.
  4. Feb 26, 2009 #3
    The observer that is being pulled into the black hole is a subject of time dilation due to the enormous gravitational field, it is possible to view this with a powerful telescope.
  5. Feb 26, 2009 #4
    Wow, thats pretty sweet. If you could somehow survive a journey to a singularity, I wonder what it would be like. With infinite curving of spacetime, ignoring that you couldn't possibly move, would the laws of physics work the same?
  6. Feb 27, 2009 #5
    The powerful gravitational pull of a black hole is immense and will pull apart anything close enough.

    The time distortion is only a matter of perspective; Imagine yourself and me sitting in a spacecraft and you are at safe distance and you have entered a stable orbit around the black hole. I go jump into the black hole, you can see me getting close and close to the singularity and then suddenly freeze, in my perspective, I would be ripped apart by the immense gravitation, but you will see me frozen for all eternity.

    No one really knows what happens if you manage to survive the entry into the singularity, but some physicists have theorized that there is something called a "white hole". These white holes are the opposite of black holes; instead of pulling you towards it, it will throw you out of it. Think of three magnets, two are positive and one is negative, you are a positive magnet, the black hole is a negative magnet and the white hole is a positive magnet. The black hole will pull you through, just like two magnets with the opposite attraction would pull towards each other, the white hole would do exactly what two magnets of the same polarity would; they would try to get away from each other.
  7. Mar 9, 2009 #6
    First, black holes do not curve spoace/time. In fact, they do not tap into, or reshape the space/time. This is so because: black holes are oney way, meaning they only swallow matter into thier core. They do not send the matter to some other point in space. To see why go to my post: why white holes do not exist. (In the astrophysics ssection.)
  8. Mar 9, 2009 #7
    White holes do not exist, they never have, they never will. To see why not go to my post. (As said in my previous reply.)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook