Is Alice burning or fuzzing?

TL;DR

The paper probes the AMPS firewall paradox by recasting the Gedankenexperiment in a decoherence framework and invoking fuzzball complementarity. It shows that the fate of an infalling wave packet depends on its energy relative to the Hawking temperature $T_H$, with $E \gg T_H$ permitting approximate free infall and $E \sim T_H$ producing stronger, but not universal, interactions. Fuzzballs—horizonless microstates—are argued to provide a unitary, information-preserving resolution, making the firewall a scale-dependent phenomenon rather than a universal feature. Overall, the work favors fuzzball complementarity as a conservative alternative to a universal firewall, highlighting the role of energy scales in black hole infall physics.

Abstract

Recently, Almheiri, Marolf, Polchinski and Sully (AMPS) have suggested a Gedankenexperiment to test black hole complementarity. They claim that the postulates of black hole complementarity are mutually inconsistent and choose to give up the "absence of drama" for an infalling observer. According to them the black hole is shielded by a firewall no later than Page time. This has generated some controversy. We find that an interesting picture emerges when we take into account objections from the advocates of fuzzballs. We reformulate AMPS' Gedankenexperiment in the decoherence picture of quantum mechanics and find that low energy wave packets interact with the radiation quanta rather violently while high energy wave packets do not. This is consistent with Mathur's recent proposal of fuzzball complementarity for high energy quanta falling into fuzzballs.

Figures (6)

• Figure 1: A wave packet far away from the horizon evolves semi-classically.
• Figure 2: One of the complementary descriptions is the wave packet passes through the horizon and hits a singularity.
• Figure 3: The other complementary description is that the wave packet gets mapped onto the degrees of freedom on a membrane. This wave packet is now scrambled, looses any semblance of itself, but the information leaks out of the membrane unitarily.
• Figure 4: Away from the horizon Postulate 2 tells us that the usual rules of quantum mechanics work. When wave packet 'Alice' crosses the wave packets 'A' and 'B' they will get entangled successively.
• Figure 5: In one complementary picture Alice having interacted with A and B falls through the horizon. Its interaction with C will depend on whether B was entangled with A or C. It then falls into the singularity.