Speed of Gravity: Experts' Opinion

[Chronos]

Ok, that seems to be a GR take on things.

Did you have a non-GR take in mind?

As stated elsewhere in this thread gravity is not a force in GR.

Agreed, gravity is not a force in the usual sense under GR, so, what is your point?

My problem is with the spin 2 graviton.

There seems to be a requirement that gravitons travel >> than the speed of light, being force carriers.

There is? By what?

What am I missing here and how is this resolved? Are gravitons optional in quantum gravity theory?

Hard to say, it is not clear what you are assuming.

 

[pervect]

There seems to be a requirement that gravitons travel >> than the speed of light, being force carriers.

What on Earth makes you think that?

As far as spin 2 gravitons go, if you quantize gravity, that's what you'd get. I'd strongly suggest to anyone and everyone that getting a basic handle on non-quantized gravity is a Very Good Idea before one gets too worked up over quantized gravity and gravitons.

 

[bayan]

Gravity does act like a magnet, there is no doubt about that!

It is just that it acts like a magnet to mass, and not to force.

Why do we not get pulled towards the Earth in space? there are many factors one is the inverse square law, the other one is the fact that you are also being pulled by the gravitational fields of other planets and stars.

 

[Nereid]

Gravity does act like a magnet, there is no doubt about that!

It is just that it acts like a magnet to mass, and not to force.

Being as respectful of your opinion as I can, it's extremely easy to demonstrate that gravity doesn't 'act like a magnet' at all - there's no 'repulsive' counterpart.

Why do we not get pulled towards the Earth in space? there are many factors one is the inverse square law, the other one is the fact that you are also being pulled by the gravitational fields of other planets and stars.

Are you joking? The motions of solar system bodies are predictable, to a very high degree of accuracy, under Newtonian physics, and if you add General Relativity, the only apparent inconsistencies are the motions of some comets (which are now well understood in terms of the 'rocket' effect of the jets).

 

[bayan]

hah!

lets get sirous now.

i was kidding about the second part, but with the first part wouldn't they be attracted to each other? when i say "act like magnet" i do not mean that they have "+" & "-" ends. Rather what i meant was that they will get "pulled towars each other". If there is an explenation why it is not like that please post.

 

[NoTime]

Did you have a non-GR take in mind?

Yes QFT, LQG.

Agreed, gravity is not a force in the usual sense under GR, so, what is your point?

That I think I have some idea of how GR does its thing?

What on Earth makes you think that?

I don't. It's actually something I have read.
With a light speed graviton the force vector points in the wrong direction.

Also, it seems to be the reason for the question "What's the speed of gravity?" in the first place.

Does this question of the speed of gravity arise from some other source?
Am I supposed to accept that gravitons are not limited to the speed of light?
Is there some way, retaining the speed of light, to handle this?
Are these quantum gravity theories just plain wrong?

 

[Nereid]

hah!

lets get sirous now.

i was kidding about the second part, but with the first part wouldn't they be attracted to each other? when i say "act like magnet" i do not mean that they have "+" & "-" ends. Rather what i meant was that they will get "pulled towars each other". If there is an explenation why it is not like that please post.

As there are no magnetic monopoles (at least, no experimental evidence of such), one cannot ignore the 'dipole' nature of magnets and magnetism 'just because'. Further, since there are no monopoles, it's very easy to demonstrate that magnetic fields don't follow the inverse square law (gravity does). Finally, there are an awful lot of 'pulled towards each other' things out in the universe - gravity, electrostatic, magnetic, springs, surface tension, ... - one needs to go at least a tiny step further before sharing 'ideas before morning coffee' with others, especially in PF.

bayan 0, Einstein+Newton 2