In Search of Cosmic Time: Complete Observables and the Clock Hypothesis

TL;DR

This paper proposes a conservative approach to the cosmic problem of time by integrating ideas from reference frames, complete observables, and measurement models to preserve Friedmann equations without radical modifications.

Contribution

It offers a novel solution that reinterprets observability criteria using the clock hypothesis and measurement models, avoiding the need to modify classical cosmological equations.

Findings

Reinterpreted observability criteria consistent with the clock hypothesis.

Preserved Friedmann equations as the universe's dynamical equations.

Provided a conservative alternative to radical modifications of cosmological models.

Abstract

This paper considers a new and deeply challenging face of the problem of time in the context of cosmology drawing on the work of Thiemann (2006, 2007). Thiemann argues for a radical response to the cosmic problem of time that requires us to modify the classical Friedmann equations. By contrast, we offer a conservative proposal for solution of the problem by bringing together ideas from the contemporary literature regarding reference frames (Bamonti 2023; Bamonti and Gomes 2024), complete observables (Gryb and Th\'ebault 2016b; Gryb and Th\'ebault 2023), and the model-based account of time measurement (Tal 2016). On our approach, we must reinterpret our criteria of observability in light of the clock hypothesis and the model-based account of measurement in order to preserve the Friedmann equations as the dynamical equations for the universe.