Chaotic light scattering around extremal black holes

We show that the scattering of light in the field of $N\ge 3$ static extremal black holes is chaotic in the planar case. The relativistic dynamics of such extremal objects reduce to that of a classical Hamiltonian system. Certain values of the dilaton coupling then allow one to apply techniques from symbolic dynamics and classical potential scattering. This results in a lower bound on the topological entropy of order $\log (N-1)$, thus proving the emergence of chaotic scattering for $N\ge 3$ black holes.