Parables of Quantum Gravity

Abstract

This thesis studies non-locality in quantum gravity from two directions. The first concerns detection: in AdS/CFT, the gravitational Hamiltonian is a boundary observable, and its correlator with a bulk operator can be nonzero at spacelike separation. We develop a single-copy boundary protocol that exploits this structure to detect a bulk excitation before any causal signal has reached the boundary. The protocol backreacts by inducing an uncertainty in the relative bulk-boundary time shift, and we show that this backreaction controls the tradeoff between detection speed and precision. The protocol fails when the bulk operator can be dressed to commute with the boundary Hamiltonian, a condition satisfied by black hole microstates. We introduce two novel dressed-operator constructions that interpolate between holographic accessibility and effective bulk locality: an emergent clock built from the energy level spacing, and an entanglement-based dressing to an external observer via a quantum wormhole. The second part concerns transport. We study two coupled critical transverse-field Ising chains and show that this system, which has no known geometric dual, exhibits several signatures of traversable wormhole transport: a thermofield-double-like ground state, coherent left-right transfer with a timescale controlled by the Ising CFT scaling dimension, and entanglement dynamics that track the signal.