I am involved in a discussion about non-locality in QM. I'm arguing that it is possible for a local mechanism to emulate a non-local one and the best example I could find is gravity (the apparently non-local force required by Newtonian gravity being explained by a local mechanism in GR). My question is if Newtonian gravity (where the force points toward the instantaneous position of each massive body) is a good approximation for all types of motion, including non-uniform accelerations. To give an example, suppose that a planet as big as Mars, coming from outside the Solar system, passes near Mars so that Mars' orbit is significantly changed. In this case, would Earth be accelerated immediately towards the new position of Mars or it will continue to accelerate towards Mars' retarded position until the signal, coming at the speed of light would arrive? Thanks!