Gravity and some classes of x-rays do escape black holes. The size of black holes,(not yet observed, by the way) is measured relative to our own sun or solar mass... Anything approaching a black hole first enters the accretion disk, which is the only thing we actually see representing a black hole, generally due the heating of the gas and dust within... If you are more than twice the diameter of the black hole away from it, the black hole acts just like any other mass and will only affect you if you happen to dive directly for it. Inside the accretion disk one approaches the event horizon, from which nothing, not even light, escapes due to the near infinite gravity and within which all the really wierd stuff happens, in theory.... simply put... much to simply put... but good for an overview...