Cosmic Expansion: A mini review of the Hubble-Lemaitre tension

Abstract

We present here a lightning review of the status of the Hubble-Lemaître tension. Instead of discussing the broad array of proposed solutions found in the literature, we focus here on the assumptions made to measure the Hubble constant from cosmic microwave background and baryon acoustic oscillation data on the one hand, and from a cepheid-calibrated distance ladder on the other hand. From this discussion, we extract two important lessons that inform which kind of physics-based solutions could plausibly resolve this tension.

Comments: 6 pages, 1 figure, contribution to the "2021 Electroweak session of the 55th Rencontres de Moriond", limited to 6 pages including references. v2: updated figure and text to address comments received