$H_0$ as a Universal FLRW Diagnostic

Understand

We reverse the logic behind the apparent existence of $H_0$-tension, to design diagnostics for cosmological models.

• The basic idea is that the non-constancy of $H_0$ inferred from observations at different redshifts is a null hypothesis test for models within the FLRW paradigm -- if $H_0$ runs, the model is wrong.
• Depending on the kind of observational data, the most suitable form of the diagnostic can vary.
• As examples, we present two $H_0$ diagnostics that are adapted to two different BAO observables.