Abstract

We argue that under certain assumptions the quantum break time approach and the trans-Planckian censorship conjecture both lead to de Sitter swampland constraints of the same functional form. It is a well known fact that the quantum energy-momentum tensor in the Bunch-Davies vacuum computed in the static patch of dS breaks some of the isometries. Proposing that this is a manifestation of quantum breaking of dS, we analyze some of its consequences. In particular, this leads to a thermal matter component that can be generalized to string theory in an obvious way. Imposing a censorship of quantum breaking, we recover the no eternal inflation bound in the low temperature regime, while the stronger bound from the dS swampland conjecture follows under a few reasonable assumptions about the still mysterious, presumably topological, high-temperature regime of string theory.

Highlights

  • Quantum breaking of dS from backreactionWe start this section by reviewing the computation of the (BD) vacuum expectation value of the energy-momentum tensor for a quantized conformal scalar field in a classical dS spacetime

  • Some of these conjectures into perspective, and to do so, let us start by briefly reviewing the relevant bounds and their origins

  • Imposing a censorship of quantum breaking, we recover the no eternal inflation bound in the low temperature regime, while the stronger bound from the dS swampland conjecture follows under a few reasonable assumptions about the still mysterious, presumably topological, high-temperature regime of string theory

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Summary

Quantum breaking of dS from backreaction

We start this section by reviewing the computation of the (BD) vacuum expectation value of the energy-momentum tensor for a quantized conformal scalar field in a classical dS spacetime. We highlight the difference between the results in FLRW coordinates and in the static patch. We provide a systematic approach to compute the latter in the center of the static patch for the non-conformal case. All this will lead us to the conjecture that quantum backreaction is a manifestation of quantum breaking. We will comment on the similarity to Rindler space which, if taken seriously, will lead to the conjecture that eternal flat Minkowski space is not a solution of (non-supersymmetric) quantum gravity, either

Brief review of the conformal case
Proposal: quantum breaking
Reduced density matrix for massive scalar
Energy-momentum tensor for massive scalar
Thermodynamics of string theory
Free energy of strings at finite temperature
Examples: type IIB and heterotic
Tachyon condensation and a new phase of strings
Low temperature regime
High temperature regime
Conclusions
A Computation of normalization constants
B Computation of individual contributions to T00 and Trr
C Limit m H in 4D
Full Text
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