Back(reaction) to the future in the Unruh-de Sitter state

Lars Aalsma, Maulik Parikh, Jan Pieter van der Schaar

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Motivated by black hole physics, we define the Unruh state for a scalar field in de Sitter space. Like the Bunch-Davies state, the Unruh-de Sitter state appears thermal to a static observer. However, it breaks some of the symmetries of de Sitter space. We calculate the expectation value of the energy-momentum tensor in the Unruh-de Sitter state in two dimensions and find a non-vanishing flux of outgoing negative energy. Extrapolating the result to four dimensions, we argue that this backreacts on the initial de Sitter geometry semi-classically. Notably, we estimate that de Sitter space is destabilized on a timescale set by the gravitational entropy; analogous to black hole evaporation, the endpoint of this instability is a singular geometry outside the regime of effective field theory. Finally, we suggest that the Unruh-de Sitter state may be a natural initial state for patches of de Sitter space, and discuss the implications for slow-roll and eternal inflation, and for de Sitter thermodynamics.

Original languageEnglish (US)
Article number136
JournalJournal of High Energy Physics
Volume2019
Issue number11
DOIs
StatePublished - Nov 1 2019

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geometry
kinetic energy
evaporation
tensors
entropy
scalars
thermodynamics
physics
symmetry
estimates
energy

Keywords

  • 2D Gravity
  • Black Holes
  • Effective Field Theories

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

Back(reaction) to the future in the Unruh-de Sitter state. / Aalsma, Lars; Parikh, Maulik; van der Schaar, Jan Pieter.

In: Journal of High Energy Physics, Vol. 2019, No. 11, 136, 01.11.2019.

Research output: Contribution to journalArticle

Aalsma, Lars ; Parikh, Maulik ; van der Schaar, Jan Pieter. / Back(reaction) to the future in the Unruh-de Sitter state. In: Journal of High Energy Physics. 2019 ; Vol. 2019, No. 11.
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