The concordance model of cosmology

Abstract We summarize the current state of observational and theoretical cosmology, epitomized by the concordance model of cosmology, in the process sketching a rough history of the universe and how we know. Three observational pillars of the concordance cosmology are: the Hubble diagram, mapping out the expansion history of the late-time universe; Big Bang Nucleosynthesis (BBN), which, combined with measurements of the primordial elemental abundances, constrains the amount of ordinary matter and early-time expansion rate; and the cosmic microwave background (CMB), which provides a view of the perturbations when the universe was less than 400,000 years old. The price of the consistent picture afforded by the concordance model of cosmology is the introduction of three ingredients beyond the Standard Model of particle physics: dark matter, dark energy, and inflation.