Firewalls in AdS/CFT

Several recent papers argue against firewalls by relaxing the requirement for locality outside the stretched horizon. In the firewall argument, locality essentially serves the purpose of ensuring that the degrees of freedom required for infall are those in the proximity of the black hole and not the ones in the early radiation. We make the firewall argument sharper by utilizing the AdS/CFT framework and claim that the firewall argument essentially states that the dual to a thermal state in the CFT is a firewall.Comment: 11 pages plus references, 8 figures; version accepted for publication in JHE

Multi-centered D1-D5 solutions at finite B-moduli

We study the fate of two-centered D1-D5 systems on T^4 away from the singular supergravity point in the moduli space. We do this by considering a background D1-D5 black hole with a self-dual B-field moduli turned on and treating the second center in the probe limit in this background. We find that in general marginal bound states at zero moduli become metastable at finite B-moduli, demonstrating a breaking of supersymmetry. However, we also find evidence that when the charges of both centers are comparable, the effects of supersymmetry breaking become negligible. We show that this effect is independent of string coupling and thus it should be possible to reproduce this in the CFT at weak coupling. We comment on the implications for the fuzzball proposal.Comment: 19 pages + appendices, 14 figures; v2: added important remark in example in introduction, rewrote first paragraph in sect 3.2 for clarity, other misc. small edits; as accepted for publication in JHE

Black holes vs. firewalls and thermo-field dynamics

In this essay, we examine the implications of the ongoing black holes vs. firewalls debate for the thermo-field dynamics of black holes by analyzing a CFT in a thermal state in the context of AdS/CFT. We argue that the themo-field doubled copy of the thermal CFT should be thought of not as a fictitious system, but as the image of the CFT in the heat-bath. While this idea was proposed earlier by Papadodimas et al., our following conclusions differ from theirs. In case of strong coupling between the CFT and the heat-bath this image allows for free infall through the horizon and the system is described by a black hole. Conversely, firewalls are the appropriate dual description in case of weak interaction of the CFT with its heat bath.Comment: 7 Pages, 4 figures. This essay received an honorable mention in the 2013 essay competition of the Gravity Research Foundation. v2: References adde

Cluster formation and anomalous fundamental diagram in an ant trail model

A recently proposed stochastic cellular automaton model ({\it J. Phys. A 35, L573 (2002)}), motivated by the motions of ants in a trail, is investigated in detail in this paper. The flux of ants in this model is sensitive to the probability of evaporation of pheromone, and the average speed of the ants varies non-monotonically with their density. This remarkable property is analyzed here using phenomenological and microscopic approximations thereby elucidating the nature of the spatio-temporal organization of the ants. We find that the observations can be understood by the formation of loose clusters, i.e. space regions of enhanced, but not maximal, density.Comment: 11 pages, REVTEX, with 11 embedded EPS file

Cool horizons lead to information loss

There are two evidences for information loss during black hole evaporation: (i) a pure state evolves to a mixed state and (ii) the map from the initial state to final state is non-invertible. Any proposed resolution of the information paradox must address both these issues. The firewall argument focuses only on the first and this leads to order one deviations from the Unruh vacuum for maximally entangled black holes. The nature of the argument does not extend to black holes in pure states. It was shown by Avery, Puhm and the author that requiring the initial state to final state map to be invertible mandates structure at the horizon even for pure states. The proof works if black holes can be formed in generic states and in this paper we show that this is indeed the case. We also demonstrate how models proposed by Susskind, Papadodimas et al. and Maldacena et al. end up making the initial to final state map non-invertible and thus make the horizon "cool" at the cost of unitarity.Comment: 22 pages + references, 4 figures. v2: References added, typos correcte