What is the reason why something, once it enters the event horizon of a black hole, it cannot escape? I've often heard the answer given that at the event horizon the escape velocity equals the speed of light, and from within the horizon a superluminal velocity is required, which is impossible. The problem I have with this explanation is that escape velocity refers to the inertial velocity an object must have in order to escape a gravitational field, with no forces acting on the object apart from gravity. But if we have other forces acting on the object (like thrust from a rocket engine), it is possible to escape from a gravitational field travelling at a velocity less than the escape velocity, by providing a force counteracting that of gravity. For instance, suppose we have a very big black hole with mass of 10^50 kg. The Schwartzchild radius will be 2GM/c^2=2(6.66x10^-11x10^50)/9x10^16=1.48x10^23 metres. The gravitational field strength at the event horizon will hence be GM/r^2 = (6.66x10^-11x10^50)/(1.48x10^23)^2= 3x10^-7 N/kg, which is almost trivial. For an object, say, a one kilogram mass one metre past the event horizon, to escape it must only overcome a measly gravitational force of 3x10^-7 N for enough time to traverse one metre, which is hardly difficult. Indeed, it should be possible to play a game of table tennis across the event horizon without noticing anything amiss. So, what is the actual reason for why the event horizon acts as a "point of no return"?