See, that was my point. I think that if gravity is subject to itself, then gravity would have to be instantaneous, which it isn’t. Unless the other assumption that it comes from the center is wrong – but then there’d be no gravity inside the hole, which also seems wrong.
I think Algernon’s right. This was my point in my previous ramblings.
Ahhh. Sorry William. My post was redundant at best. Upon rereading, you did clearly state my own conclusion.
I haven’t thought deeply about this, but I believe the answer to your question lies again in the nature of gravity, atarian. That is to say, the thing that’s propogating is the curvature of spacetime, not necessarily a physical object like, say, a photon, propogating in spacetime. Does that make any sense?
Which, on preview, is what everyone else said. So I’ll just add a me too instead.
Which immediately suggests an extremely cool idea. If we could somehow manage to modulate gravity waves, they could not be blocked by anything. We’d still communicate at the same rate, and there’d still be ‘noise’, but they’d go through the planet, happy as you please.
Hm.
Umm, I think you’d have a problem with that in that the gravity waves would still interact with the planet, for example, and would presumably be affected in doing so. This might, for example, take the form of an energy lost, hence a frequency shift, and that sort of thing, as well as scattering.
I have no idea how large of an effect this would be, but of course if the planet (which is a pretty big detector) didn’t interact with gravitational radiation, then an antenna (which is a pretty small detector) wouldn’t do so either.
Good point, the gravity waves would push-pull the planet which would alter the planet’s own gravity-well, introducing gravitational ‘noise’.
Question is for the black hole issue, though, would the modulated waves pass through the gravity well itself unhindered… if gravitational waves are affected by gravitational wells even when the waves don’t impact the mass, we’re back to an interesting pickle.
I’m not a relativist (where’s Chronos or someone like that when you need them?), so I’m not sure about this, and I could easily be wrong. I believe, though, that you would find that the black hole would affect gravitational radiation (remember: mass tells space how to curve, which is all gravitational radiation ultimately is), but since there’s nothing physical for the black hole to “suck in,” it wouldn’t stop anything from gravitating. Whether a planet, for example, has crossed the event horizon of a black hole or not, it still attracts things to it. This does not change the basic fact that the planet and the black hole also attract each other.
As I said, though, I’m a little far afield from my area of expertise here, so take this with a big grain of salt.
I once asked how a black hole could have charge (which is mediated by an exchange of photons) if photons could not escape the BH. The answer (it wasn’t that long ago and someone could dredge it up) was that the photons were virtual photons and not subject to the speed of light limitation. So I guess these gravitons are also virtual. This is not a very satisfactory answer, but I guess it will have to do.
Gravitational waves are a source of gravitation. All energy and momentum, in whatever form, are a source of gravitation. From Weinberg’s Gravitation and Cosmology:
Just some food for thought:
Gravity is different from the other three fundamental forces. Of Strong Nuclear, Weak Nuclear, Electromagnetic and Gravity you’ll find that gravity is the only one you can’t shield yourself from.
Don’t know how that plays into energy esacaping a Black Hole but we are talking about a different beast here. There’s a reason that gravity is what gives QM fits.