Cosmological tensions in the era of precision cosmology: Insights from Tensions in Cosmology 2025

The paper operates within the established ΛCDM (Lambda-Cold Dark Matter) or "concordance model" of cosmology. This paradigm, which posits a universe dominated by a cosmological constant and cold dark matter, has successfully explained cosmological observations for decades. The paper's focus is on the growing observational challenges to this paradigm, namely the Hubble (H₀) and S₈ tensions, and the exploration of alternative theoretical frameworks that might resolve them.

This paper documents a scientific field in a state of Model Crisis. The dominant ΛCDM paradigm is confronted by persistent and increasingly robust anomalies, specifically the H₀ and S₈ tensions, which are described as "cracks in the concordance model." The community's response, as reported here, has shifted from suspecting systematic errors to "cautious recognition" that new physics may be required. This has led to a proliferation of alternative theories and a focused effort to test the foundations of the standard model, which are defining characteristics of a Kuhnian crisis preceding a potential scientific revolution.