Failure of Perturbation Theory Near Horizons: the Rindler Example

Persistent puzzles to do with information loss for black holes have stimulated critical reassessment of the domain of validity of semiclassical EFT reasoning in curved spacetimes, particularly in the presence of horizons. We argue here that perturbative predictions about evolution for very long times near a horizon are subject to problems of secular growth - i.e. powers of small couplings come systematically together with growing functions of time. Such growth signals a breakdown of naive perturbative calculations of late-time behaviour, regardless of how small ambient curvatures might be. Similar issues of secular growth also arise in cosmology, and we build evidence for the case that such effects should be generic for gravitational fields. In particular, inferences using free fields coupled only to background metrics can be misleading at very late times due to the implicit assumption they make of perturbation theory when neglecting other interactions. Using the Rindler horizon as an example we show how this secular growth parallels similar phenomena for thermal systems, and how it can be resummed to allow late-time inferences to be drawn more robustly. Some comments are made about the appearance of an IR/UV interplay in this calculation, as well as on the possible relevance of our calculations to predictions near black-hole horizons.Comment: LaTeX, 17 pages plus appendix; added references and subsection on back-reactio

L'Invention du Troisième Peuple: The utopian vision of Philippe Grandrieux's dystopias

In Philippe Grandrieux's 1999 film, Sombre, a Punch and Judy show puppeteer, Jean (Marc Barbe), turns out to have much in common with the Big Bad Wolf whose costume he dons in the climax of his puppet show, for he is a figure of primordial and archetypal terror, a vicious serial killer who preys on women and who seems to show no emotion whatsoever in the face of the fear and suffering of his victims. Jean, like the Big Bad Wolf, displays neither regret, sadness nor pleasure at the kill-it is just what he does. A character with no apparent redeeming features whatsoever, it thus comes as somewhat of a surprise when Claire (Elina Lowensohn), who we suspect will become his next victim, appears to fall in love with Jean, or, at least, to be irresistibly drawn to him even as she recognises the danger that he embodies. More surprising still, perhaps, for contemporary audiences accustomed to neat resolutions, is that it is resolutely not the case in Sombre that this scenario is established in order for Jean finally to achieve redemption, to leave behind his murderous ways and start a new life with Claire. On the contrary, just as the very possibility of this relationship resists comprehension, which is to say integration into a predetermined system, so the relationship itself is destined not to last and itself to fall prey to the incommensurability upon which it is premised, Jean finally abandoning Claire and returning to the primeval space of the forest. [Chapter extract