2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54528We discuss the limitations of 't Hooft's proposal for the black hole S-matrix. We find that the validity of the S-matrix implies violation of the semi-classical approximation at scales large compared to the Planck scale. We also show that the effect of the centrifugal barrier on the S-matrix is crucial even for large transverse distances.12 pagesHigh Energy Physics - Theorytext