An often overlooked problem in black hole physics is that the inner horizon of stationary black holes do not (generically) exist even in the equilibrium state (i.e. the Hartle-Hawking state), due to the divergence of quantum fields. Even though this behavior has been observed numerically in 2+1 and 3+1 dimensions for free fields, a universal and analytic understanding of it is lacking. I will discuss work in progress on trying to fill this gap.
