CDM in a courtroom

arXiv:2609.16097 · astro-ph.CO · Submitted 2026-09-14 · Read on arXiv

astro-ph.CO

Submitted: 2026-09-14

Updated: 2026-09-14

Comments: 15 pages, 1 Table, 1 Figure; a Perspective article accepted for publication by Nature Astronomy and to appear in the October 2026 issue

License: http://creativecommons.org/licenses/by/4.0/

The gist: The cosmological constant Λ, and its generalization as Dark Energy, makes up roughly 70% of the present-epoch universe and has been part of the dominant Λ CDM cosmological paradigm for more than a

Terminology

Dark Energy Survey — 8× in this paper
Calibration — 7× in this paper · explained in 7 episodes
Cosmic Microwave Background — 6× in this paper
Clustering — 5× in this paper · explained in 2 episodes
Dynamical Dark Energy — 4× in this paper
Quintessence — 4× in this paper · explained in 2 episodes
Atacama Cosmology Telescope — 3× in this paper
Weak Lensing — 3× in this paper · explained in 2 episodes
Commentary — 2× in this paper · explained in 2 episodes
Generalization — 2× in this paper · explained in 13 episodes
Gravitational Lensing — 2× in this paper · explained in 2 episodes
Hubble Tension — 2× in this paper · explained in 9 episodes
Accuracy — 1× in this paper · explained in 1 episode
Alignment — 1× in this paper · explained in 1 episode
Bayesian Framework — 1× in this paper · explained in 3 episodes
Consistency — 1× in this paper · explained in 3 episodes
Dark Energy Spectroscopic Instrument — 1× in this paper
F and Sloan Digital Sky Survey — 1× in this paper
Figure of Merit — 1× in this paper
South Pole Telescope — 1× in this paper
Systematic Bias — 1× in this paper · explained in 3 episodes
Wide-field Spectroscopic Telescope — 1× in this paper

Abstract

The cosmological constant Λ, and its generalization as Dark Energy, makes up roughly 70% of the present-epoch universe and has been part of the dominant Λ CDM cosmological paradigm for more than a quarter of a century. It has been put on trial by recent measurements of galaxy clustering, Type Ia supernovae, and the cosmic microwave background. In this Perspective we evaluate the strength of the evidence for a constant Λ, versus Dynamical Dark Energy (DDE) in the light of recent developments. We also assess what the future holds both for our Universe and our understanding of its most mysterious component.

Terminology

Abstract

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