(May 8, 2011 at 5:16 pm)little_monkey Wrote: Sorry for being late on this thread. However, that is totally wrong. The speed of light near a black hole, or anywhere else, is the same. Deny that, and you're denying the foundation of Special and General Relativity.
Inside the black hole, the light doesn't escape because it is bent by gravity into a circle, and so doesn't escape, but its speed remains the same. Outside the BH, your clock will slow down and your ruler will shrink, nevertheless, you will end up measuring the speed of light to be c.
Actually, this is not quite true. The problem with general relativity is that things can be coordinate dependant. Take for example the Schwarzschild geometry: from the time Schwarzschild came up with it during the first world war (whilst fighting in the trenches, no less) up until the 1960's, everyone thought that the singularity at the schwarzschild radius was a real physical effect, but it turns out to be just an artifact of the coordinates.
The coordinate speed of light can be non-constant (or =/= c), but the proper speed is always c. An observer that doesn't know about relativity that wants to measure the speed of light in a non-inertial frame will measure (distance travelled by light measured by my ruler) / (time elapsed on my clock) which is the average coordinate speed which could be something other than c.
For the example of a black hole you gave, the coordinate speed of light at the surface of a black hole is zero whereas it's proper speed is c.
Regardless, the quran says nothing about any of this!
Galileo was a man of science oppressed by the irrational and superstitious. Today, he is used by the irrational and superstitious who claim they are being oppressed by science - Mark Crislip
