Standard laws of physics seem to lead to contradictions when applied to the quantum states a black hole can be in. This implies that black holes must be important clues to help us improving the formulation of these laws. On the one hand, space and time seem to become discrete, on the other they become topologically non-trivial. To gain control over the way black holes process information, it is advised to use spherical harmonics, in terms of which the problems reduce to simple partial differential equations that we can solve, just as in the hydrogen atom.