Making use of the fact that the optical geometry near a static nondegenerate Killing horizon
is asymptotically hyperbolic, we investigate some universal features of black-hole horizons …

We construct a gedanken experiment, in which a weak wave packet of the complex massive
scalar field interacts with a four-parameter (mass, angular momentum, electric and magnetic …

Abstract The Penrose-Gibbons inequality for charged black holes is proved in spherical
symmetry, assuming that outside the black hole there are no current sources, meaning that …

We formulate conditions on the geometry of a nonexpanding horizon Δ which are sufficient
for the spacetime metric to coincide on Δ with the Kerr metric. We introduce an invariant …

We prove that (possibly charged) test fields satisfying the null energy condition at the event
horizon cannot overspin/overcharge extremal Kerr–Newman or Kerr–Newman–anti de Sitter …

By examining the rate of growth of an invariant volume V of some spacetime region along a
divergence-free vector field v α, we introduce the concept of a “vector volume” V v. This …

It is widely believed that the complete gravitational collapse of a body always results in a
black hole (ie,“naked singularities” can never be produced) and that all black holes …

The weak cosmic censorship conjecture asserts that spacetime singularities that arise in
gravitational collapse are always hidden inside of black holes, invisible to distant observers …

We present a number of open problems within general relativity. After a brief introduction to
some technical mathematical issues and the famous singularity theorems, we discuss the …

Recently, several authors have studied the possibility of overspinning or overcharging an
existing black hole to destroy its event horizon and make the central singularity naked. When …