The Time in Thermal Time

TL;DR

The paper critically examines the thermal time hypothesis in quantum gravity, questioning whether it can genuinely generate time without presupposing dynamics, thus challenging its foundational validity.

Contribution

It highlights a potential circularity in the thermal time hypothesis, arguing that it may require pre-existing dynamics to define time, which undermines its foundational premise.

Findings

Identifies a circularity problem in the thermal time hypothesis.

Argues that defining time thermodynamically may presuppose dynamics.

Raises doubts about the hypothesis's ability to generate time independently.

Abstract

Preparing general relativity for quantization in the Hamiltonian approach leads to the `problem of time,' rendering the world fundamentally timeless. One proposed solution is the `thermal time hypothesis,' which defines time in terms of states representing systems in thermal equilibrium. On this view, time is supposed to emerge thermodynamically even in a fundamentally timeless context. Here, I develop the worry that the thermal time hypothesis requires dynamics -- and hence time -- to get off the ground, thereby running into worries of circularity.