# Gravitons and black holes

1. Dec 30, 2009

### cgw

Maybe a simple or stupid question so bear with me (it is late and I just thought of this). Assuming the existance of gravitons and assuming they are mass-less and travel the speed of light - how can they escape a black hole? Please point me in the right direction.

2. Dec 31, 2009

### Troponin

I've always wondered that myself. I figured it is explained by gravitational field theory, which I have yet to learn.

3. Dec 31, 2009

### arunma

I've wondered about this too. I've also wondered about why charged particles don't "glow" with virtual photons (my nuclear physics professor told me once, but I forgot the explanation). I think the answer to these two questions might be the same. I think this might have something to do with the uncertainty principle.

4. Dec 31, 2009

### diazona

For the gravity case, here's a thought: a distant observer never actually sees a black hole form. The observer would just see a shell of matter falling inward more and more slowly, asymptotically approaching the Schwarzschild radius as time goes on. So if I'm interpreting this right, you could say that all the gravitational waves that are ever going to escape from the black hole's gravity well are emitted in the "short time" it takes for the infalling matter to reach $r = 2M$.

Right now I'm wishing I hadn't missed a lecture on gravitational wave production a few weeks ago... :-(

5. Dec 31, 2009

### DaveC426913

It is. But a quantum theory of gravity, by definition, is - well - quantized, which means it is incompatible with a field theory of gravity.

6. Jan 1, 2010

### cgw

Not sure I get this. Elect-mag radiation is quantized and is compatable with field theory. Right?