Helping observers in closed universes reach their full potential

TL;DR

This paper advances the understanding of observer roles in holographic models of closed universes, showing how improved operators can refine predictions about the universe's structure from different observer perspectives.

Contribution

It introduces new operators for holographic maps that enhance the accuracy of universe descriptions for both AdS and closed universe observers.

Findings

AdS observer cannot definitively rule out a baby universe.

Closed universe observer can improve the accuracy of their universe description.

New operators enable better predictions in holographic models.

Abstract

Recent work by Engelhardt, Gesteau, and Harlow applies proposals for incorporating observers into holographic maps to study the Antonini-Rath puzzle for closed universes. In a new form of ``observer complementarity,'' they find that an AdS bulk observer measures a SWAP test to determine that there is no closed universe in the bulk, contrary to the (limited) description given by an observer inside the closed universe. In this work, we improve the predictions of both observers by using the holographic maps to define new operators to perform this same SWAP test. With these, we show that the AdS observer cannot rule out a baby universe in the bulk, and the closed universe observer can improve the accuracy of their description.