A New Area Law in General Relativity

TL;DR

This paper introduces a new area law in General Relativity, demonstrating that the area of future holographic screens increases monotonically, with implications for black hole physics and cosmology.

Contribution

It establishes the first rigorous area law for holographic screens in cosmological and gravitational collapse scenarios, independent of the Bousso bound.

Findings

Monotonic area increase of future holographic screens

Existence of past holographic screens in expanding universes

Finite-time identification of these objects without asymptotic boundaries

Abstract

We report a new area law in General Relativity. A future holographic screen is a hypersurface foliated by marginally trapped surfaces. We show that their area increases monotonically along the foliation. Future holographic screens can easily be found in collapsing stars and near a big crunch. Past holographic screens exist in any expanding universe and obey a similar theorem, yielding the first rigorous area law in big bang cosmology. Unlike event horizons, these objects can be identified at finite time and without reference to an asymptotic boundary. The Bousso bound is not used, but it naturally suggests a thermodynamic interpretation of our result.