Starting from Einstein's theory of general relativity, Oppenheimer and Snyder found solutions... that described what happens to a massive star when it has exhausted its supplies of nuclear energy. The star collapses gravitationally and disappears from the visible universe, leaving behind only an intense gravitational field to mark its presence. The star remains in a state of permanent free fall, collapsing endlessly inward into the gravitational pit without ever reaching the bottom. ... In my opinion, the black hole is incomparably the most exciting and the most important consequence of general relativity. But Einstein ... was actively hostile to the idea of black holes. ... Oddly enough, Oppenheimer too in later life was uninterested in black holes, although... they were his most important contribution to science. ... Oppenheimer in his later years believed that the only problem worthy of attention of a serious theoretical physicist was the discovery of fundamental equations of physics. Einstein certainly felt the same way.
Freeman Dyson