String-theoretic breakdown of effective field theory near black hole horizons

摘要

We investigate the validity of the equivalence principle near horizons instring theory, analyzing the breakdown of effective field theory caused bylongitudinal string spreading effects. An experiment is set up where a detectoris thrown into a black hole a long time after an early infalling string. Lightcone gauge calculations, taken at face value, indicate a detectable level ofroot-mean-square longitudinal spreading of the initial string as measured bythe late infaller. This results from the large relative boost between thestring and detector in the near horizon region, which develops automaticallydespite their modest initial energies outside the black hole and the weakcurvature in the geometry. We subject this scenario to basic consistencychecks, using these to obtain a relatively conservative criterion for itsdetectability. In a companion paper, we exhibit longitudinal nonlocality inwell-defined gauge-invariant S-matrix calculations, obtaining resultsconsistent with the predicted spreading albeit not in a direct analogue of theblack hole process. We discuss applications of this effect to the firewallparadox, and estimate the time and distance scales it predicts for new physicsnear black hole and cosmological horizons.