A pedagogical approach to the black hole information issue

TL;DR

This work provides a pedagogical account of black hole information loss within semiclassical gravity and argues there is no paradox, consistent with GR and QFT in curved spacetime. It details the classical definitions of black holes, the Hawking effect, and entanglement, showing that the emitted radiation is near-thermal and entangled with interior degrees of freedom. It then argues that complete evaporation leads to a non-unitary evolution from a global pure state to a mixed state for exterior observers, due to the singularity and loss of interior information. The author cautions that proposals to preserve unitarity at all scales contradict well-tested semiclassical physics, and that quantum gravity is required to address Planck-scale details.

Abstract

We provide a pedagogical introduction to the concepts underlying black hole information loss, intended for readers familiar with special relativity and quantum mechanics. We emphasize that there is no paradox of information loss, and that proposals suggesting deviations from well-established theories at arbitrary regimes are inherently contradictory.

Figures (13)

• Figure 1: Qualitative description of the gravitational interaction proposed by GR.
• Figure 2: Qualitative description of the interactions in QFTCS. The dashed line represents the fact that in this framework there is no general description of backreaction effects.
• Figure 3: Future and past of an event, $a$, in two-dimensional Minkowski spacetime. The illustration contains a timelike curve (blue) and null curves (black).
• Figure 4: Conformal diagram of Minkowski spacetime with two angular coordinates suppressed. The illustration contains null curves (black), a timelike curve (blue), and a three-dimensional spacelike section (red).
• Figure 5: Conformal diagram of Minkowski spacetime illustrating two Cauchy surfaces (red), $\Sigma_0$ and $\Sigma_1$.