Firewalls in the non-perturbative bulk Hilbert space of JT gravity
Hamed Zolfi
TL;DR
This work advances a non-perturbative treatment of the JT gravity bulk by employing a bulk inner product inspired by random-matrix models to incorporate baby universes and wormholes. It introduces an operator $\mathcal{O}(a)$ to encode a single emitted baby universe and constructs a non-perturbative geodesic inner product, enabling a consistent analysis of wormhole geometries with and without baby-universe emission. The key findings show that, at very late times, the probabilities for smooth and firewall geometries saturate to constant values (plateau behavior) instead of diverging, with explicit expressions capturing the dependence on spectral data and baby-universe parameters; however, equality between the two probabilities is not established at genus one. The results illuminate how non-perturbative bulk dynamics in JT gravity shape interior-probing observables, connect to SFF plateau physics, and raise open questions about the precise non-perturbative no-shortcut condition and the interplay between baby universes and wormhole geometry.
Abstract
It has been shown that a very old black hole can tunnel into a white hole through the emission of a large baby universe. This process can be modeled by a genus-one geometry corresponding to a single baby universe emission, with a tunneling probability proportional to \( t^{2} e^{-2S(E)} \), where \( t \) denotes the black hole age and \( S(E) \) its entropy at energy \( E \). The growth of this probability at late times raises the question of its behavior near \( t \sim e^{S} \). A natural possibility is that the full genus expansion, together with its non-perturbative completion, leads to saturation of the tunneling probability. Motivated by this idea, the present analysis employs a non-perturbative bulk inner product in place of the perturbative one and shows that, at late times, the probabilities of realizing firewall geometries and smooth geometries approach constant values.