Event Category: String Seminar

String Seminar:
Tuesdays at 3:40pm on campus

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Abstract: Classically, the volume of the Einstein-Rosen bridge of the two-sided black hole grows linearly in time. Such linear increase is in conflict with the finite black hole entropy S, thus at late time, the volume should be upper-bounded and saturate at the time scale O(e^S). The bulk mechanism of such saturation is due to the production of baby universes … Read More

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Abstract: In this talk, I will discuss a class of many body chaotic models related to the Brownian Sachdev-Ye-Kitaev model. An emergent symmetry maps the quantum dynamics into a classical stochastic process. Thus we are able to study many dynamical properties at finite N on an arbitrary graph structure. This talk is mainly based on paper arxiv: 2308.11123, but it is … Read More

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Summary: $\alpha’$ corrections to near horizon dynamics of a Schwarzschild black hole in a large number of spacetime dimensions $D$ are governed by the worldsheet theory composed of the cigar CFT and the classical sigma model on the sphere at the horizon, along with a timelike-Liouville theory of central charge $26-D$. At leading order in weak string coupling, black hole thermodynamics … Read More

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Abstract Should we include a sum over wormhole topologies in the path integral of quantum gravity? While doing so has been very useful in the last few years, it also leads to features that are inconsistent with traditional holography, like the lack of factorization of the partition function on disconnected boundaries. In this talk, I will propose a systematic algorithm … Read More

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Abstract: It was recently understood that holographic BPS states can be divided into two categories: monotone and fortuitous. Various pieces of evidence suggest that monotone states correspond to horizonless microstate geometries, while fortuitous states are dual to supersymmetric black holes. In this talk, I will connect this classification to the fine-grained features of these states using concepts from quantum chaos. … Read More

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Abstract: In this talk, we first present a detailed analysis of the classical geometry of generic null hypersurfaces. We then reformulate the Einstein equations as conservation laws for the intrinsic geometric data on these hypersurfaces. Following this, we derive the symplectic structure and the corresponding Poisson bracket. Upon quantizing this phase space, we propose that the projected Einstein tensor obeys … Read More

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Abstract: Thermal correlators in large N systems equilibrate at late times, but the precise late-time behavior is unknown away from holographic and free field limits. In this talk I will analyze this problem in the case of the SYK model away from the low-temperature limit. The basic technique is a resummation of perturbation theory which is reminiscent of the double … Read More

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Abstract: We employ a probabilistic mesoscopic description to draw conceptual and quantitative analogies between Brownian motion and late-time fluctuations of thermal correlation functions in generic chaotic systems respecting ETH. We apply this formalism to the case of semiclassical gravity in AdS3, showing that wormhole contributions can be naturally identified as moments of stochastic processes. Adopting this perspective shows that semiclassical gravity … Read More

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The Gibbons-Hawking-York (GHY) term was added by hand to the Einstein-Hilbert action to establish a well-defined variational principle on spacetimes with boundaries. In string theory, the equations of motion of target spacetime are derived from the beta functions on the worldsheet, from which an action is subsequently inferred. In string field theory, the action is reconstructed from the off-shell amplitudes. … Read More