The Singularity is Not a Point

It is widely stated in the popular literature that the singularity at the center of a (Schwarzschild) black hole is a point. It's not true. Two observers who infall radially at different angular positions become causally disconnected from each other already well away from the singularity. Although the spatial distance between the infallers goes to zero at the singularity, the causal distance between them remains finite. The singularity is a surface of spherical topology, the points of which are causally disconnected from each other. Although classically the timelike dimension terminates at the singular surface, quantum mechanically the surface must evolve unitarily from one (Schwarzschild) time to the next. If string theory is the correct theory of quantum gravity, then the singular surface, not the horizon, is a brane.