Black Holes: Complementarity or Firewalls?

TL;DR

This paper discusses the black hole information paradox, arguing that maintaining all three classical assumptions leads to contradictions, and suggests that the infalling observer likely encounters a firewall at the horizon.

Contribution

It critically analyzes the compatibility of Hawking radiation purity, information emission location, and the experience of infalling observers, proposing the firewall hypothesis as a resolution.

Findings

All three classical assumptions cannot hold simultaneously.

The firewall hypothesis implies the infalling observer encounters high-energy phenomena.

Maintaining semiclassical physics at macroscopic distances from the horizon is problematic.

Abstract

We argue that the following three statements cannot all be true: (i) Hawking radiation is in a pure state, (ii) the information carried by the radiation is emitted from the region near the horizon, with low energy effective field theory valid beyond some microscopic distance from the horizon, and (iii) the infalling observer encounters nothing unusual at the horizon. Perhaps the most conservative resolution is that the infalling observer burns up at the horizon. Alternatives would seem to require novel dynamics that nevertheless cause notable violations of semiclassical physics at macroscopic distances from the horizon.