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4h ago

Study Reaffirms Cosmic Acceleration After Rebutting 2025 Deceleration Claim

A peer‑reviewed MNRAS paper finds key calibration mistakes in the 2025 analysis and so restores confidence in supernova-based measurements of dark energy.

Image
Studying Type Ia supernovae – violent, luminous white dwarf star explosions – led to the Nobel Prize-winning discovery that the universe’s expansion is accelerating. This image combines data from four space telescopes to create a multi-wavelength view of all that remains of RCW 86, the oldest documented example of a supernova. (Credit: X-ray: NASA/CXC/SAO & ESA; Infared: NASA/JPL-Caltech/B. Williams (NCSU))

Overview

  • The University of Southampton‑led paper published in Monthly Notices of the Royal Astronomical Society identifies errors in the 2025 Yonsei study and concludes the universe’s expansion is still accelerating.
  • The authors say the earlier paper wrongly treated host‑galaxy age as the same as the exploding star’s age and omitted standard corrections for host‑galaxy mass, which together biased its supernova brightness calibration.
  • The rebuttal, published June 11, includes Nobel laureates Adam Riess and Brian Schmidt and shows that when supernovae are recalibrated for host environment and population, the acceleration signal remains robust.
  • The Yonsei team has posted and submitted counter‑arguments on arXiv, so the technical dispute over progenitor age mapping and calibration methods remains active rather than settled.
  • By restoring confidence in Type Ia supernova distance measures, the new paper shifts attention back to characterizing dark energy and to independent checks from other datasets and analyses such as DESI.