What does it mean to have a quantum gravitational theory of de Sitter Space?

TL;DR

This paper discusses the implications of representing de Sitter space as a finite-dimensional quantum system, highlighting ambiguities in modeling and the limitations of measurement in understanding the universe.

Contribution

It explores the theoretical ambiguities in modeling de Sitter space as a finite quantum system and the constraints of measurement on such models.

Findings

Semi-classical considerations imply ambiguity in models of de Sitter space.

Experiments cannot measure more than a tiny fraction of the system's quantum bits.

Embedding models in string theory may lead to a precise mathematical description.

Abstract

We argue that if de Sitter space is indeed represented by a finite dimensional quantum system, then semi-classical considerations, combined with the fundamental principles of quantum measurement theory, imply that any theoretical model of it is ambiguous. If our own universe asymptotes to such a de Sitter state, and if a model of it as a finite system can be embedded in a sequence of models that converges to a non-perturbative completion of a unique superstring model in asymptotically flat space, then one might be able to find a very precise mathematical model of our universe. However, even the most comprehensive experiments possible to local detectors in the universe cannot measure more than a tiny fraction of the total number of q-bits in the system.