: Consider the following system: A black hole with a given schwarzschild radius and a particle with positive energy with respect to the gravitational field of the black hole. If the particle is sent towards the black hole in such a direction that it will pass through the event horizon, and we presume that the particle does not interact in other ways with the black hole than gravitationally, why cant this particle escape the black holes gravitational field? : The energy of the particle should be constant while only interacting gravitationally with the black hole, and thus still be a free particle with respect to the gravitational field from the black hole, even though it is inside of the event horizon. What mechanism makes it impossible for the particle to escape again?

Short answer: gravitational field is too strong - escape velocity is greater than the velocity of light.

• Re: Event horizon and escape velocity - Pranov/">Pranov - February 24, 2000 - 20:28 UTC