Breakthrough Tracker record

DESI evidence for evolving dark energy

DESI’s three-year data combined with CMB and supernova datasets initially produced a 2.8σ–4.2σ preference for time-varying dark energy, depending on dataset and model. A sequential reanalysis finds the signal specification dependent, while DESI’s newer full-shape Lyman-α measurement shifts its high-redshift central value toward ΛCDM and updates the combined preference to 2.7σ–3.2σ.

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Stable ID: desi-evolving-dark-energy-2025
Revision: desi-evolving-dark-energy-2025.v3
Field: Physics · Cosmology and dark energy
Evidence: Tier 1 · Peer reviewed: Yes
Record state: Provisional · Provisional and model dependent
Last checked: 2026-09-04

AI role

No AI assistance was disclosed as a contributor to the core cosmological result.

Record details

Problem or result: Whether dark energy changes over cosmic time rather than behaving as a cosmological constant
Authors: DESI Collaboration and independent cosmology teams
Institutions: Dark Energy Spectroscopic Instrument collaboration and partner institutions
Result date: DESI DR2 March 19, 2025; full-shape Lyman-alpha update July 29, 2026

Why it matters

Confirmed evolving dark energy would require a major revision of the standard cosmological model.

Limits

No combination establishes a discovery, and the inference changes with dataset, calibration, redshift probe, parameterization and statistical specification. The official Lyman-alpha update is consistent with ΛCDM and could mean the earlier hint will fade, while its combined fits still modestly prefer an evolving model. Required wording remains evidence suggesting evolving dark energy, model- and dataset-dependent.

Sources

Primary: DESI collaboration’s official Data Release 2 results guide
Primary: DESI official interpretation
Independent: Model-independent reconstruction in JCAP
Independent: Revised-supernova analysis in European Physical Journal C
Independent: Dark Energy Survey Year 6 cosmology results
Independent: DES Year 6 multi-probe analysis
Independent: Sequentially valid DESI dynamical-dark-energy reanalysis
Primary: DESI full-shape Lyman-alpha results guide
Primary: DESI DR2 full-shape Lyman-alpha analysis

Correction and revision history

2026-07-29 — Replaced the retired DR2 data-documentation path, which now returns 404, with the DESI collaboration’s live official results guide; the scientific status is unchanged.
2026-08-22 — Added the e-process reanalysis showing a fragile, single-bin, specification-dependent signal; provisional status retained.
2026-09-04 — Added DESI’s full-shape Lyman-alpha analysis, whose central value shifts toward ΛCDM and reduces the combined evolving-dark-energy preference; provisional status retained.

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