Hello. I was thinking. The collapse of a stellar nucleus into a black hole is an apparent contradiction to the Pauli exclusion principle, right? So which one of those theories fails at that point - quantum mechanics or the theory of relativity? I used to think that it's the theory of relativity because it's accurate in predicting the existence of black holes but not very good at describing what's inside them. Also, to me the exclusion principle seems too fundamental to fail. However, recently I took a course is astrophysics and if I understood correctly then during the collapse the density gets higher than that allowed by the exclusion principle (the degeneracy pressure). And that made me confused. Can anyone shed some light on this?