An Observer's Measure of De Sitter Entropy

The two-point correlation function of a massive field, measured along an observer's worldline in de Sitter (dS), decays exponentially in time. Meanwhile, every dS observer is surrounded by a horizon and the holographic interpretation of the horizon entropy S_dS suggests that the correlation function should stop decaying, and start behaving erratically at late times. We find evidence for this expectation in Jackiw-Teitelboim gravity by finding a topologically nontrivial saddle, which is suppressed by exp(-S_dS), and which gives a constant contribution to the norm squared of the correlator. This constant might have the interpretation of the late-time average over all microscopic theories that have the same low-energy effective description. Based on arxiv-2311.07724.