Quantum-mechanical instability of the Kerr-Newman black-hole interior

The behavior of the conserved stress-energy tensor of a quantized massless field in a Kerr-Newman black-hole spacetime is studied. In the Unruh vacuum state, and under the assumption that certain stress-energy tensor components are analytic functions of $a$, the Kerr angular momentum parameter, it is shown that the stress-energy tensor must diverge on at least one of the two inner event horizons. A weaker assumption, simple continuity, suffices to guarantee that the stress-energy tensor diverges on the inner horizon of all slowly rotating Kerr-Newman black holes. This perturbation singularity invalidates the Kerr-Newman interior as a counterexample to strong cosmic censorship, and closes off the "space bridge" to other asymptotically flat exterior "universes."