Evita Verheijden (University of Amsterdam, Netherlands)
Date & Time
Wed, 13 October 2021, 15:00 to 16:30
Online Seminar

One of the greatest puzzles in our universe, which can -- to good approximation -- be described by de Sitter space, is a proper understanding of the cosmological horizon that surrounds any observer. Over the past few years, a semi-classical approach involving quantum extremal surfaces and so-called ‘islands’ has been very successful to increase our understanding of the black hole information problem; in light of these advancements, it could prove fruitful to undertake a similar approach to investigate an evaporating de Sitter horizon. In this talk I will consider such an approach for two-dimensional de Sitter space. Starting from three-dimensional de Sitter space, I will show how a partial dimensional reduction supplies 2D JT de Sitter with an auxiliary system acting as a heat bath. I will then contrast the time-dependent entropy of radiation collected by an observer at future infinity with that collected by an observer inside the static patch. Central to the analysis in the static patch is the identification of a weakly-coupled region close to the cosmological horizon. I will highlight how backreaction considerations crucially obstruct both observers from witnessing unitary evaporation.

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