Einstein himself resisted the black hole implications of his own theory

Thorne recounts how Karl Schwarzschild found an exact solution to Einstein's field equations within months of their publication in 1915, a solution that implied an object so dense that nothing, not even light, could escape its gravity. Einstein, however, spent years arguing that such an object could never actually form in nature, treating the mathematics as a formal curiosity rather than a physical prediction his own theory demanded be taken seriously. Thorne frames this resistance as psychologically understandable rather than a simple oversight: a genuine singularity, a point of infinite density where physics as understood breaks down entirely, offended Einstein's sense that a complete theory shouldn't produce such a breakdown. It took subsequent generations of physicists, working through the math more rigorously, to show that collapse into such an object was not just possible but likely for sufficiently massive dying stars. Takeaway: even a theory's own creator can be the last person willing to accept where it actually leads.