Speaker
Description
The teleological nature of black hole horizons, e.g. for finding their location it is necessary to track the focussing properties of a bundle of light rays in the full spacetime although general relativity is a local theory, has been tamed a few years ago. In fact, it has been proved that the location of the horizon corresponds to the algebraic zeroes of some appropriate curvature invariants. In my talk, I will elaborate on the mathematical foundation of this technique and also point out some motivations from the physical side for trying to further extend it. Specifically, I will discuss the applicability of this method in lower-dimensional gravitational theory in which the Weyl part of the curvature is trivial mentioning some potential physical applications in light of the AdS/CFT correspondence. Next, I will get back to astrophysical settings discussing the evolution of the horizon of the McVittie spacetime, and of another black hole spacetime which arises as a solution in a number of different gravitational theories. I will also explain why it is relevant to know the location of the dynamical apparent horizon in some spacetimes in light of the cosmological holographic principle. Finally, I will show that a certain combination of curvature invariants may serve as an appropriate notion of density of gravitational entropy consistent with the Weyl curvature conjecture.
