To H0 or not to H0?

TL;DR

This paper critically examines late-time physics modifications as a solution to the Hubble tension, demonstrating they are strongly constrained and proposing a more rigorous statistical approach to H0 estimation.

Contribution

It clarifies misconceptions about distance ladder measurements and introduces a dynamics-free inverse distance ladder method to assess late-time physics effects.

Findings

Late-time physics modifications are observationally constrained.

Inappropriate use of H0 priors can mislead conclusions.

A new statistically rigorous scheme for H0 estimation is proposed.

Abstract

This paper investigates whether changes to late time physics can resolve the `Hubble tension'. It is argued that many of the claims in the literature favouring such solutions are caused by a misunderstanding of how distance ladder measurements actually work and, in particular, by the inappropriate use of a distance ladder H0 prior. A dynamics-free inverse distance ladder shows that changes to late time physics are strongly constrained observationally and cannot resolve the discrepancy between the SH0ES data and the base LCDM cosmology inferred from Planck. We propose a statistically rigorous scheme to replace the use of H0 priors