Cosmic Expansion: A mini review of the Hubble-Lemaitre tension
  We present here a lightning review of the status of the Hubble-Lema\^itre
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.
