Falling Into Black Hole
Imagine a spaceship near a black hole. I have heard
that time dilation may take place around the black hole due to its
gravity warping space-time. My question is: what would an observer
from a far-away distance see as the spaceship approached the black
hole? I have heard
a) the spaceship would seem to disappear in an instant and
b) the spaceship would seem to hold its position near the edge of
the black hole forever.
Which if either is right?
Well, b is more correct than a, but in a qualified sense. Let us
say you are observing the spaceship by reflected light. The light
traveling from the spaceship to you is red-shifted as the spaceship
approaches the event horizon of the black hole. This gravitational
red-shift is an effect of time dilation, and, in fact, light from
the ship at the event horizon will continue to be sent to you forever.
However, you will not be able to see the ship very well for very
long. Because of the time dilation, the flux (brightness) of light
will be very low, as the time between photons (for you, not the
ship) will constantly increase. Also, the red shift will quickly
stretch the light waves from the visible to infrared, then
microwave, and finally very long radio waves. Not much to see there.
University of Wyoming
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Update: June 2012