General Relativity is the name for Einstein’s theory of gravity, in which gravity can be thought of as an effect of the warping of space and time. General relativity is not a quantum theory; it predicts exactly what happens, not probabilities for various things to happen.It was gradually understood, over the years from 1915 to 1958, that extremely compact and massive objects form black holes. Gravity becomes immensely strong in their vicinity… strong enough to warp space-time dramatically, with the effect that any object that gets too close, and crosses the black hole’s horizon — a surface of no-return — can never escape. which shows a black hole horizon forming when two shells of matter become sufficiently compact. The information about these two shells goes inside the horizon and never can come out… in general relativity.