is emitted, conservation of momentum requires that forces between objects (either electromagnetic or gravitational forces) point at objects' instantaneous and up-to-date positions, and not in the direction of their speed-of-light-delayed (retarded) positions. However, since no information can be transmitted from such an interaction, such influences (which seem to exceed that of the influence of light), cannot be used to violate principles of relativity. See also Faster than light Liénard–Wiechert potential Further reading Does Gravity Travel at the Speed of Light? in The Physics FAQ General relativity