Newton's equations concerning gravity I understand. I think I also have a reasonable grasp of the outlines of gravity in General Relativity. It makes sense to me that the force of gravity is caused by the curvature of spacetime; meaning that even the supposedly massless photon is subject to the force. I believe this is supported by observable evidence such as the gravitational lensing of light from distant stars / galaxies. Quantum gravity I am not comfortable with. If gravity is caused by the distortion of spacetime by mass, why is there the requirement for a force carrying exchange particle, such as the theoretical graviton? If the graviton does exist, is it subject to the same cosmic speed limit as other particles (i.e. the speed of light)? If the graviton does travel through spacetime at a finite speed, does this mean that if a mass, A, is introduced to an area of space where another mass, B, already resides (a certain distance away from A), there will be a delay between the time of the introduction of mass A, and the time at which mass B begins to feel the effect of mass A's gravitational field (i.e. the time it takes the gravitons to cover the distance between mass A and B)?
This could be true whether you accept gravitons or not; the "curvature of spacetime" would propagate at c in the same manner that waves in your sheets do as you're making the bed.
