" With general relativity, we know that before gravity can act, spacetime has to deform. This process does not happen instantaneously. It takes time. Gravity waves travel at the speed of light. Gravitational effects can kick in at a given position only after the time it takes for a signal to travel there and distort spacetime. "

― Lisa Randall , Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions