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Re: Black Holes=Time Travel?????????????

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Posted by richard/">richard on June 23, 1999 19:24:34 UTC

: I would love to hear some thoughts on this.

: As I understand it, as you approach a black hole (specifically the event horizon) time slows down for you as compared with the rest of the universe. Therefore, it is impossible for an obsover to see anything actually enter the event horizon, the light would just slowly go out. As long as you dont enter the event horizon, you're free to leave, so why couldnt you get within a foot or so of the event horizon (true it would have to be a frickin huge black hole so you wouldnt be torn appart by the tidal forces) so that one minute to you might be a few million years in the rest of the universe. Then you could leave the black hole and see what has happend to the universe. Is our sun still around? Are we?????

What you speak of is true for the observer. The observer never sees the test object cross the event horizon But it's not true for the test object. In the frame of the test object, it crasses the event horizon immediately without realizing that it has been crossed. This is because onlt the external observer has an event horizon. The actual object falling into the black hole sees no horizon. Furthermore, the test object does not have to be moving because it is space itself that is falling into the black hole from the perspective of an external observer. The velocity of space equals the speed of light in the external frame at the event horizon. For the test object to get within one foot of the event horizon and then stop, it would therefore have to be going at the speed of light away from the black hole with respect to the local frame of reference.

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