I've read conflicting accounts on this subject. Some say it does, some say it doesn't, some say the entire idea of relativitic mass is a "rampant pedagogical virus". So please inform me when I'm making a mistake. So does the gravity of an object it exerts on it surroundings increase with it's speed? If so, consider the following experiment. A space ship nearing the light speed just whooses past a star so that v->c. The captain then orders to speed up the space ship with a precisely calculated amount so as to make the star "gain" just enough mass to collapse in a black hole, seen from the frame of reference of the space ship. However at almost exactly the same time the increased gravity the black hole exerts on it surroundings just about slows the ship down so that the mass "created" by the space ships velocity is lessened as well and makes it mass too low to remain a black hole. Would the black hole suddenly explode into a star again? ?Does this not contradict the rule that no causal influences can leave a black hole? Or does a relativistic black hole not count? Do only black holes with a restmass large enough -or small enough, depending how you look at it- for its schwartshield radius count? Now the best explanation I have is that when the space ship slows down the black holes schwartshield radius recedes inward, however the black holes interior recedes inward even faster. But I'm not sure if the math adds up, since you can just deaccelerate arbitrarily fast; Obviously this doesn't really need to the gravity slowing down the ship. It could be giant magnets or just a very sturdy wall.