Speed of Light constant

[earlybird]

Since the latest explanation by the Hong Kong scientist confirming the speed of light constant upholding Einstein's speed of light postulate, which states that nothing can go faster than the speed of light and conversely light can go no slower than its constant speed. My question for anyone (or obviously an expert) is how can the speed of light be explained within a black hole? If precisely the speed of light according to the viewers stance arrives at a "dead stop" once it is captured by the black hole's grasp. Anyone please explain this so it can make perfect sense (in words and examples please) to the mathematically ignorant and for that instance to everyone.

Edited July 26, 2011 by earlybird

[Ophiolite]

My question for anyone (or obviously an expert) is how can the speed of light be explained within a black hole?

I'm answering as anyone. (I'm obviously not an expert.)

The path of a light ray is bent within a gravitational field. The more intense the field the the light bends. Therefore in an intense gravitational field, the bending will prevent the light departing from that field.

[mathematic]

The physics inside a black hole has never been worked out, so your question really can't be answered. Photons might spiral into the center, but that is just a guess.

[ajb]

It is a subtle question. The speed of light depends on the coordinates used to describe the space-time. What special relativity says is that in all inertial frames of reference the speed of light is constant. That is even on a flat space-time one needs to select the inertial frames in order for the speed of light to be constant, c. That is in special relativity there are special frames of reference, the inertial ones. However, other frames are equally as valid, but not usually convenient. In these non-inertial frames the speed of light is almost never going to be c.

 

On a curved space-time one has that equivalence principle. This basically says that in a small enough region about a point the space-time is flat. Thus one can always find a local inertial frame. In this frame the speed of light is "locally" constant. There is no violation of special relativity as such, it all holds in small enough regions.

 

Photons might spiral into the center, but that is just a guess.

 

I think you can examine null geodesics inside a black hole in your favourite coordinates. It might not be easy to interpret these, but it can be done I am sure.

[MigL]

I don't want to go as deep as AJB ( doubt that I could ), but I believe you answered your own question. You state the speed of light is fixed at c , yet you ask how can light slow down as it tries to escape a black hole, and stop just inside the event horizon. Obviously it cannot.

 

What it can do, however, is loose energy as it tries to climb out of a very steep gravitational well such that it is infinitely red-shifted and never leaves the event horizon.

 

I hope this explanation makes the process easier to visualize.

Edited July 28, 2011 by MigL