Snowmass2021-Letter of interest cosmology intertwined IV: The age of the universe and its curvature

A precise measurement of the curvature of the Universe is of prime importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early-Universe scenarios. Recent observations, while broadly consistent with a spatially flat standard A Cold Dark Matter (ACDM) model, show tensions that still allow (and, in some cases, even suggest) a few percent deviations from a flat universe. In particular, the Planck Cosmic Microwave Background power spectra, assuming the nominal likelihood, prefer a closed universe at more than 99% confidence level. While new physics could be at play, this anomaly may be the result of an unresolved systematic error or just a statistical fluctuation. However, since positive curvature allows a larger age of the Universe, an accurate determination of the age of the oldest objects provides a smoking gun in confirming or falsifying the current flat ACDM model. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A precise measurement of the curvature of the Universe is crucial for cosmology as it can confirm primordial inflation and differentiate between early-Universe scenarios. Recent observations show tensions which may suggest slight deviations from a flat universe, with a preference for a closed universe in some cases. This anomaly could be due to new physics, unresolved systematic errors, or statistical fluctuations, with positive curvature potentially providing evidence for or against the current flat ACDM model.