Smoothing the Bouncing-Geodesic Singularity in AdS/CFT

Abstract

Black hole singularities remain a central open problem in quantum gravity. In the AdS/CFT correspondence, bulk spacelike extremal surfaces can probe the black hole interior, and information about the near-singularity geometry is encoded in analytically continued boundary correlators. As the bouncing geodesic approaches the black hole singularity, it becomes nearly null and gives rise to characteristic divergences at complex times. Importantly, these complex-time singularities emerge only in the strict semiclassical limit ($G_N\to 0$ or $c\to\infty$) and are governed by the asymptotically linear quasinormal mode (QNM) spectrum. At finite $c$, nonlinear deformations of the QNM trajectories produce suppression kernel that smooths out the complex-time singularities. Using Liouville CFT as an analytically solvable example, we explicitly demonstrate the finite-$c$ deformation of the QNM spectrum and its associated pole-zero structure. We also identify a complementary Gaussian smoothing mechanism arising from finite-energy fluctuations in the thermal spectral decomposition. These results show how finite $G_N$ quantum corrections modify the holographic imprints of the classical black hole singularity.