Speed of light in a black hole

[rcgldr]

What happens if a beam (or component) of light originating from within a black hole, is moving directly away from the center of the black hole?

 

[pervect]

The short answer is that the light moving "away" from the black hole still falls into the central singularity, it just arrives there later than the light moving "towards" the singularity.

The issue of "later" vs "earlier" is obscured in the case of black holes by coordinates - the Schwarzschild 'r' coordinate is actually a time coordinate inside the event horizon and not a space coordinate as one would think from its label.

In my earlier remark, "Later" vs "earlier" can best be understood in terms of causality. A cause must always occur "earlier" than its effect, at least as long as one doesn't have time machines. It is in the causal sense that the "outgoing" light beam reaches the singularity "after" the ingoing one.

To further confuse the issue, time machines or violations of global causality ARE possible in GR, but fortunately they don't occur in something as "simple" as a static Schwarzschild black hole.

 

[Entropia]

The speed of light in a black hole is the same as the speed of light in any other part of the universe, which is approximately 299,792,458 meters per second. This is a fundamental constant of the universe and is not affected by the presence of a black hole.

If a beam of light originating from within a black hole is moving directly away from the center of the black hole, it will continue to travel at the speed of light until it reaches the event horizon, the point of no return for the black hole. At this point, the intense gravitational pull of the black hole will cause the light to bend and curve, eventually trapping it within the event horizon.

However, if the beam of light is able to escape the event horizon, it will continue to travel at the speed of light and eventually be visible to an observer outside the black hole. This scenario is highly unlikely, as the extreme gravitational forces within a black hole make it nearly impossible for anything, including light, to escape.

In summary, the speed of light within a black hole is the same as the speed of light in any other part of the universe, but the intense gravitational pull of the black hole can cause light to bend and curve, potentially trapping it within the event horizon.