Event Category: String Seminar

String Seminar:
Tuesdays at 3:40pm on campus

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Abstract: Spacetime inversion symmetries such as parity and time reversal play a central role in physics, but they are usually treated as global symmetries. In quantum gravity there are no global symmetries, so any spacetime inversion symmetries must be gauge symmetries. In particular this includes CRT symmetry (in even dimensions usually combined with a rotation to become CPT), which in … Read More

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Abstract:  The construction of de Sitter vacua remains a core problem for string theory. A leading proposal, put forth 20 years ago by Kachru, Kallosh, Linde, and Trivedi, calls for the insertion of antibranes into a supersymmetric AdS vacuum with a conifold. In this talk, we provide evidence for the existence of such vacua. We begin by constructing the first … Read More

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Abstract: We show that a generic extremal black hole in AdS is singular. In four dimensions, the horizon is replaced by a mild null singularity. That leaves significant imprints on the BH thermodynamics at sufficiently low temperatures. In five dimensions, that singularity becomes more serious. In particular, it makes RN AdS an unstable IR fixed point. Many new fixed points … Read More

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Abstract: Zhenbin Yang and I proposed that wormhole effects can turn very old black holes into white holes (firewalls). Checking the proposal has been difficult due to the lack of a good definition of the infalling observer. I will describe the setup and some of the subtleties. Bio: I am an Associate Professor at Stanford University.

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Abstract: We introduce a framework for quantifying random matrix behavior of 2d CFT and AdS_3 quantum gravity that is manifestly compatible with conformal and modular invariance. We explain what it means to isolate the chaotic part of the Virasoro primary spectrum of a given theory. This leads to a 2d CFT trace formula, analogous to the Gutzwiller trace formula for … Read More

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Abstract. I will discuss a new holographic duality between a 1d theory, the q-Schwarzian, and certain 2d dilaton gravity theories. This q-Schwarzian is a one parameter deformation of the well known Schwarzian theory. For real values of q, upon quantization, the q-Schwarzian mechanics exactly reproduces DSSYK amplitudes. For values of q on the unit circle, it exactly reproduces Liouville gravity … Read More

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Abstract: The direct observation of gravitational waves provides a powerful new lens with which to explore the cosmos. In this talk, I will share recent observational developments illustrating how these measurements can be used to not only give tantalising clues into our early Universe, but also pin down new physics far beyond reach of laboratory experiments. One particularly fruitful avenue, … Read More

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The Hawking-Page phase transition in holography is associated with the emergence of new symmetries and dynamical properties of correlators. Above the transition point: (1) Correlators cluster in time (Maldacena’s information loss) (2) There exists a coarse-grained entropy that grows monotonically in time (Second law) (3) A large class of correlators decay exponentially (Quasi-normal modes) (4) There is an emergent approximate … Read More

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Abstract — Boundaries in gravitational systems are essential for defining observables. When an asymptotic boundary is absent, finite size boundaries may be employed to get a grasp of various properties of the system. In this presentation I will discuss how introducing a boundary in the static patch of de Sitter space helps understanding its thermodynamics, specifically entropy derivation and proper … Read More

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Abstract: The averaged null energy operator is a light-ray integral of the null energy. This operator is known to be closely tied to causality in AdS/CFT, to deformations of the modular Hamiltonian in quantum field theory, and to the Lorentzian inversion formula in CFT. I will discuss a new connection between averaged null energy and the monotonicity of the renormalization … Read More