How was the theory of the black holes developed?

Answer 1

Black hole theory was a natural consequence of Einstein's general theory of relativity, which was an extension to his earlier special theory of relativity that incorporated gravity. This was presented as a group of field equations, the first solution to which, done by astrophysicist Karl Schwarzchild, led to the understanding of the final stages of gravitational collapse of a massive object like a star.

Relativity predicted that if a mass was compact enough, spacetime would be sufficiently distorted that gravity would prevent anything, including light, from escaping. After Schwarzchild's solution, other solutions were found for charged and spinning black holes (such as those of Roy Kerr). Various other scientists continued development from within the relativistic framework and more fully described properties of black holes, including Penrose, Eddington, Chandresekhar, and many others. Further contributions such as those from Hawking extended black hole theory based on quantum mechanical effects.

Prior to publication of the theories of relativity there was conjecture that an object massive enough could potentially gravitationally attract another object such that its rate of fall would accelerate until it approached the speed of light - and thus considered in reverse, there might be an object massive enough to prevent light from escaping; while in essence this would be a black hole, but many of the implications were not described before the extensions to Einstein's work.