Computational complexity and black hole horizons

Entropy and black hole horizons

The standard approach of counting the number of eigenmodes of N scalar fields near the horizon is used as a basis to provide a simple statistical mechanical derivation of the black hole entropy in two and four dimensions. The Bekenstein formula S = A 4Gh̄ and the two-dimensional entropy S = 2M/λh̄ are naturally obtained (up to a numerical constant of order 1). This approach provides an explanatio...

Quantum isolated horizons and black hole entropy

We give a short introduction to the approaches currently used to describe black holes in loop quantum gravity. We will concentrate on the classical issues related to the modeling of black holes as isolated horizons, give a short discussion of their canonical quantization by using loop quantum gravity techniques, and a description of the combinatorial methods necessary to solve the counting prob...

Energy and information near black hole horizons

The central challenge in trying to resolve the firewall paradox is to identify excitations in the near-horizon zone of a black hole that can carry information without injuring a freely falling observer. By analyzing the problem from the point of view of a freely falling observer, I arrive at a simple proposal for the degrees of freedom that carry information out of the black hole. An infalling ...

Black-Hole and White-Hole Horizons in Superfluids

Ripplons – gravity-capillary waves on the free surface of a liquid or at the interfaces between two superfluids – are the most favourable excitations for simulation of the general-relativistic effects related to horizons and ergoregions. The white-hole horizon for the “relativistic” ripplons at the surface of the shallow liquid is easily simulated using the kitchen-bath hydraulic jump. The same...

Black holes and black hole thermodynamics without event horizons