Weak cosmic censorship, superradiance, and quantum particle creation

Starting in 2007, a string of papers argue about if the weak cosmic censorship conjecture (WCCC) can be violated by classically forbidden interactions between particles and slightly subextremal black holes, occurring via the quantum nature of the particles; and where backreaction and/or superradiance are pointed out as effects working in the direction of preserving the WCCC. We correct/modify a backreaction argument, point out that transmission/reflection coefficients for relativistic wave equations are not the respective probabilities, and conclude that superradiance does not prevent single particles from being captured by the black hole; even if this capture would lead to WCCC violation. Then we consider the spontaneous emission (which we call the Zel'dovich-Unruh ``ZU'' effect) of particles by the black hole, and point out that it completely invalidates the mentioned single- or few-particle thought experiments. We find that at least for scalars, the ZU effect can be understood without second quantization; and reevaluate our previous work on scalar fields interacting with black holes in view of this new understanding, finding that it becomes inconclusive.