What is fastest the speed of light or the instant pull of gravity?
Within Newtonian gravitational theory, gravity acts instantly at a distance – according to the inverse square law. However, according to Einstein’s Special Theory of Relativity (1905) no signal can travel faster than the speed of light! Within Einstein’s General Theory of Relativity (1915), gravity is viewed to be the curvature or distortion of space-time due to the presence of mass-energy. Thus, a massive star distorts the space-time around it and an orbiting planet follows the ‘path of least action’ around it. However, within Einstein’s theory of gravity the propagation or spread of the effects of the gravity cannot travel faster than the speed of light. Thus, to answer your question – if the largest giant star possible just appeared out of nowhere; its light and the gravitational pull would reach a planet at almost the same instant according to the theories of Special and General Relativity!
