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

TL;DR

The paper reports on the 2025 Tensions in Cosmology meeting, documenting the persistence and sharpening of key cosmological tensions, notably in $H_0$ and $S_8$, with the community increasingly favoring new physics beyond $\Lambda$CDM over unrecognized systematics. It synthesizes high-precision data from DESI, JWST, ACT, and gravitational-wave probes, alongside advanced statistical and modeling approaches (e.g., non-Gaussian likelihoods, Gaussian-process reconstructions, emulators, and forward-modeling frameworks) to test global consistency across probes. The contributions cover the robustness of the $H_0$ discrepancy (local ladders vs. early-Universe inferences), the evolving status of the $S_8$ tension under multiprobe analyses, and the emergence of novel theoretical directions (early dark energy, sign-switching $\Lambda_s$CDM, interacting dark sectors, $f(T)$/$f(Q)$ gravity) as viable partial solutions. The paper emphasizes a data-driven shift toward global, multiprobe validations and highlights gravitational-wave cosmology and future surveys (Euclid, Roman, LSST, SO) as critical to determining whether tensions fade or compel a paradigm shift in cosmology.

Abstract

The ``Tensions in Cosmology'' series of conferences has been established as one of the main venues where the cosmological community collectively assesses the cracks in the concordance model and explores possible theoretical and observational remedies. The 2025 edition, held once again in Corfu, Greece, came at a crucial time: the Hubble constant $H_0$ discrepancy has now exceeded $6σ$, and new high-precision data from DESI, JWST, ACT, and other facilities have made this tension more robust while opening new windows on the early and late Universe. The $S_8$ tension, though milder and survey-dependent, remains an important probe of late-time structure formation, while emerging anomalies involving dynamical dark energy and neutrino physics are gaining increasing attention as potential signs of physics beyond $Λ$CDM. Here we provide a report on the meeting and an update on the state of the tensions in 2025, highlighting progress since the pioneering 2022 event.

Figures (1)

• Figure 1: Recent determinations of the Hubble constant $H_0$ from a variety of methods. Local distance-ladder approaches, including Cepheid- and TRGB-calibrated Type Ia supernovae, surface-brightness fluctuations, Type II supernovae, the Tully–Fisher relation, Mira variables, carbon stars, strong-lensing time-delay cosmography, fast radio bursts, the DESI fundamental plane with the Coma cluster, and maser distances, consistently favor $H_0 \simeq 71$--$77~{\rm km\,s^{-1}\,Mpc^{-1}}$. In contrast, early-Universe inferences from the CMB and BAO within $\Lambda$CDM yield lower values, around $H_0 \simeq 66$--$68~{\rm km\,s^{-1}\,Mpc^{-1}}$. Updated from CosmoVerseNetwork:2025alb.