Laplace agreed with Isaac Newton that light is made up of particles. He theorized that if enough mass were added to a star, the gravitational force would become so great that its escape velocity would equal the speed of light. When Einstein developed his special theory of relativity, he argued that nothing can move faster than light. This means that Laplace's black stars are also black holes, because if light can't escape, all other matter would be trapped also. The black hole concept was expanded upon by the German astronomer Karl Schwarzschild in 1916 on the basis of Albert Einstein's theory of general relativity.
Black holes arise in general relativity, a classical theory of gravity.
The presence of a singularity in the classical theory also means that once we go sufficiently far into the black hole, we can no longer predict what will happen. Physics as we know it no longer applies. Also, according to general relativity, gravitation severely modifies space and time near a black hole. As the horizon is approached from outside, time slows down relative to that of distant observers, stopping completely on the horizon. Black holes may form during the course of stellar evolution.