Gravity & Force From Black Holes: How Do Photons Escape?

[black hole 123]

this seems like a dumb question but i just can't think of a solution. black holes can suck photons, that's why they are black. but there are charged black holes, and the EM forces is mediated by photons, so how can the mediating photon escape the gravity? also arent the gravitons (i know gravitons is unconfirmed...) themselves subject to the same thing? so in other words black holes should just be a dot in space with no force around it.

 

[PeterDonis]

how can the mediating photon escape the gravity?

It doesn't have to, just as the black hole's gravity itself doesn't have to "escape" the hole to act on objects outside it. See this Usenet Physics FAQ article:

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_gravity.html

 

[bcrowell]

An explanation I've seen is that the Coulomb force is transmitted by virtual photons, which don't have to travel at c. I'm not strong enough at field theory to know whether this is really a rigorous explanation.

 

[PeterDonis]

An explanation I've seen is that the Coulomb force is transmitted by virtual photons, which don't have to travel at c.

The Usenet article mentions this, but it links to other articles which discuss the limitations of this view. Also, as the article notes, virtual photons are a quantum concept, and it should be possible to have a classical explanation of what's going on (which the article provides).

 

[bcrowell]

Also, as the article notes, virtual photons are a quantum concept, and it should be possible to have a classical explanation of what's going on (which the article provides).

The OP's question was explicitly quantum-mechanical.

I don't see why there would be any mystery classically.

 

[PeterDonis]

The OP's question was explicitly quantum-mechanical.

In the sense that the term "photon" was used, yes, it is on its face. But that term gets used a lot to mean something that is much more accurately described as either a classical EM field or a classical "pulse of EM radiation". Also, physically speaking, unless the black hole is of very small mass, a classical description should be sufficient.

I don't see why there would be any mystery classically.

I don't think there is either, but I'm not sure the OP realized that there isn't.