Just speed as a magnitude; forces don't have speed correct? I was trying to explain something to a friend, and it was very hard for me to express or explain in English. He had to drop Physics after classical mechanics. So it's very difficult arguing with him. We got on the subject of gravity and the idea of, "speed of gravity." Is it instant or does it travel at the speed of light. According to something done in 2003, Einstein was correct that gravity correct on that there is a speed of gravity and it's the speed of light. However, I've read other things done where it refuted that their experiment wasn't valid? We have not taken upper-level Physics yet. I referred back to Einstein and Newton. He believed in what Newton believed and I believed in what Einstein believed. He believed gravity was instant and I believe it was at the speed of light. Forces don't have speed, but their affects may affect speed? Force of gravity is instant, but the affect of gravity travels at the speed of light? If that is true, then how does gravity have a speed and is not instant? It has to either travel as a wave or a particle or as something "physical?"