Hi everybody, and thanks in advance. My doubt is: why should the mass go in the singularity? I'm thinking about this situation: imagine a sphere with radius R<2M; then that sphere generates a BH. Schwarzschild tensor metric is valid only in the exterior region of the mass and for this reason i can't use it to "achieve" the singularity and to explain how the matter behaves there... So how can I say that the matter of the sphere falls inside the BH to the singularity? And why? Thanks.