Early-Universe Hubble Solutions Erase Apparent Evidence for Dynamical Dark Energy

The letter from Schöneberg and collaborators shows that claims of dynamical dark energy arise mainly from late-time reconstructions that implicitly fix early-Universe parameters at Planck values. When H0 rd is allowed to increase and Ωm to decrease—values generically produced by early dark energy or varying electron mass models before recombination—the Bayesian evidence for w(z) evolution drops below decisive thresholds. This occurs because the same parameter shifts that ease the Hubble tension also flatten the required late-time equation-of-state trajectory.

The result links two previously separate tensions: the Hubble discrepancy and the apparent need for evolving dark energy. Reconstructions that marginalize over early parameters or adopt early dark energy priors recover a cosmological constant within 1–2σ, while purely late-time analyses can exceed 3σ. The dependence is strongest for the combination H0 rd > 100 Mpc and Ωm < 0.30, the region preferred by most early-Universe resolutions.

Current data cannot yet distinguish whether the apparent dynamics are an artifact of mismatched early cosmology or a genuine late-time phenomenon. Next-generation BAO and supernova surveys that tighten H0 rd independently of the CMB will provide the decisive test. If those measurements remain near the higher H0 rd values, reconstructions should converge back toward ΛCDM without additional parameters.