Is the firewall consistent?: Gedanken experiments on black hole complementarity and firewall proposal

TL;DR

This paper examines the theoretical consistency of firewalls in black hole physics, questioning their placement and impact on classical and quantum theories, and introduces a model with disconnected horizons to explore these issues.

Contribution

It proposes a gravitational collapse model with a false vacuum lump to analyze firewall placement and its effects on black hole complementarity and spacetime structure.

Findings

Firewall can exist outside the event horizon without apparent horizon

Firewall modifies both general relativity and semi-classical quantum field theory

Disconnected apparent horizons can occur in certain collapse scenarios

Abstract

In this paper, we discuss the black hole complementarity and the firewall proposal at length. Black hole complementarity is inevitable if we assume the following five things: unitarity, entropy-area formula, existence of an information observer, semi-classical quantum field theory for an asymptotic observer, and the general relativity for an in-falling observer. However, large N rescaling and the AMPS argument show that black hole complementarity is inconsistent. To salvage the basic philosophy of the black hole complementarity, AMPS introduced a firewall around the horizon. According to large N rescaling, the firewall should be located close to the apparent horizon. We investigate the consistency of the firewall with the two critical conditions: the firewall should be near the time-like apparent horizon and it should not affect the future infinity. Concerning this, we have introduced a gravitational collapse with a false vacuum lump which can generate a spacetime structure with disconnected apparent horizons. This reveals a situation that there is a firewall outside of the event horizon, while the apparent horizon is absent. Therefore, the firewall, if it exists, not only does modify the general relativity for an in-falling observer, but also modify the semi-classical quantum field theory for an asymptotic observer.