de Sitter Bubbles and the Swampland

TL;DR

This paper explores the instability of de Sitter spaces suggested by Swampland conjectures, constructing effective scalar theories that depict a cascade of decaying de Sitter bubbles, and finds that the Trans-Planckian Censorship Conjecture (TCC) encompasses other criteria, limiting eternal inflation.

Contribution

It constructs dual effective theories of decaying de Sitter spaces constrained by Swampland criteria, revealing TCC's overarching role and implications for eternal inflation.

Findings

TCC constrains the form of effective potentials.

Decaying de Sitter bubbles form a cascade process.

Eternal inflation is marginally ruled out.

Abstract

A number of Swampland conjectures and in particular the Trans-Planckian Censorship Conjecture (TCC) suggest that de Sitter space is highly unstable if it exists at all. In this paper we construct effective theories of scalars rolling on potentials which are dual to a chain of short-lived dS spaces decaying from one to the next through a cascade of non-perturbative nucleation of bubbles. We find constraints on the effective potential resulting from various swampland criteria, including TCC, Weak Gravity Conjecture and Distance Conjecture. Surprisingly we find that TCC essentially incorporates all the other ones, and leads to a subclass of possible dual effective potentials. These results marginally rule out emergence of eternal inflation in the dual effective theory. We discuss some cosmological implications of our observations.