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Old 18-February-2006, 01:26 AM
Jeff Root Jeff Root is offline
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Join Date: Dec 2004
Location: Minneapolis
Posts: 4,315
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Quote:
Originally Posted by Astrowannabe
As you fall towards the event horizon of the black hole, time
dialation will slow down the passage of time.
That isn't true. Time dilation is something which is seen by
an observer in a different state of motion or in a different
gravitational potential from whatever he is observing. If I
am the dumb astronaut falling into the black hole, and you are
the smart astronaut watching me from a good distance away, you
will see me time-dilated and redshifted. If you were even
dumber than me, and came with me into the black hole, leaving
nobody behind to tell the sad story or return our spacecraft to
the rental shop, we would not see each other time-dilated or
redshifted.

Quote:
Originally Posted by Astrowannabe
Or, for the unfortuante infalling astronaut, he will see the
time for the rest of the universe speed up.
That isn't accurate, either. If I fall into the black hole
from a good distance away, I will be moving at very nearly the
speed of light relative to you as I cross the event horizon,
and I will be accelerating downward away from the light which
is coming into the black hole after me. I say "away from" but
I didn't mean to imply that I'm getting farther from the light--
I'm not-- but I'm moving fast enough that I will reach the
singularity before the light can reach me. On the other hand,
if I were to slow my fall into the black hole somehow, so that
I was falling at much less than the speed of light as I crossed
the event horizon, then you *would* be right: The rest of the
Universe would appear to be speeded up.

Quote:
Originally Posted by Astrowannabe
The infalling matter may take longer to reach the black hole
(it'll take forever in fact)
Only relative to a distant observer. The infalling matter sees
rapid acceleration to the singularity, accompanied by gratuitous
spaghettification.

That pretty well obviates your main question.

-- Jeff, in Minneapolis
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