I'm just wondering what we know about the speed of gravity. a) Is the gravitational force determined by mass or a combination of mass and energy? b) As a planet orbits the sun, can we discern its position by detecting its gravitational force instantly and therefore see it slightly ahead of its reflected light? Or does the gravitational force information take time to get to us? c) If a star burns up at a great distance away, is the missing gravitational force detectable instantly? Or does it take time for the stellar event to reach us as does the light from that star? d) If we were able to create mass and then destroy mass in a repetitive manner, and if gravitational force effect is instantaneous, then can we broadcast information instantly to any other part of the universe? (Thus exceeding the speed of light)? The above questions are purely curiosities in my head. But is seems to me if g-force is instantaneous, then that is remarkable. And if g-force changes travel at some velocity then that is equally remarkable! Oh well! Any takers?