Cosmological tensions

The standard cosmological model has been extraordinarily successful in explaining a wealth of detailed data about the cosmic microwave background (CMB) and the galaxy distribution in the current Universe. The model requires, though, the introduction of some new form of matter to make up the dark matter and also some reason why the vacuum has a nonzero energy density. It also requires some new physics to explain the flatness of the early Universe and its primordial density perturbations. Finally, there has arisen, over the past decade, a discrepancy between the cosmological expansion rate inferred from the CMB and galaxy distribution and that obtained with local measurements. This "Hubble tension" is not easily resolved without the introduction of yet some more new physics. I will discuss these issues and some possible resolutions.