Yikun Jiang + Yiming Chen - Special JC on Islands

Monday 10 Aug 2020, 15:00 → 17:00 Europe/Zurich

Zoom only (CERN)

Zoom virtual seminar: Click here to enter room

 

Special JC on islands in cosmological settings and bra-ket wormholes.

 

Speaker 1: Yikun Jiang 15:00-15:45

Title: Islands in cosmology

Abstract: A quantum extremal island suggests that a region of spacetime is encoded in the quantum state of another system, like the encoding of the black hole interior in Hawking radiation. We study conditions for islands to appear in general spacetimes. They must violate Bekenstein's area bound in a precise sense, and the boundary of an island must satisfy several other information-theoretic inequalities. These conditions combine to impose very strong restrictions, which we apply to cosmological models. Using these conditions as guidance, we find several examples of islands in crunching universes. In this talk, I will mainly focus on the example of four-dimensional FRW cosmology with radiation and a negative cosmological constant entangled with an auxiliary non-gravitational Minkowski spacetime in the thermofield double state, where an island appears near the turning point when the geometry begins to recollapse. If time permits, I will also briefly explain our results for islands in two-dimensional models of JT gravity in de Sitter spacetime. The talk will be based on work: 2008.01022 with Thomas Hartman and Edgar Shaghoulian.

 

Speaker 2: Yiming Chen 15:45-16:30

Title: Bra-ket wormholes in gravitationally prepared states

Abstract: In this talk I will discuss states prepared by Euclidean AdS_2 evolution or Lorentzian dS_2 evolution in JT gravity. We probe the properties of the states mainly using the gravitational fine grained entropy formula. In such computations, I will argue that it is both natural and necessary to consider wormholes that connect the bra and the ket. I will discuss some interesting features of these bra-ket wormholes.