A new study concludes that the universe's expansion is not accelerating, challenging the existence of dark energy. Researchers led by Subir Sarkar at the University of Oxford used updated supernova data to reach this finding.
The analysis, published in the Monthly Notices of the Royal Astronomical Society, examined the Pantheon+ catalogue of 1701 Type Ia supernovae. It incorporated corrections suggesting these explosions appear dimmer in younger galaxies, which could have led previous studies to overestimate cosmic expansion rates.
Sarkar began reviewing the original 1990s claims in 2014 after data became public. The team argues the evidence for acceleration did not meet discovery thresholds and now believes their latest work addresses prior criticisms.
Reactions among cosmologists remain divided. Dominik Schwarz of the University of Bielefeld called the observation potentially impactful, while Joshua Frieman of SLAC National Accelerator Laboratory said robust evidence from multiple sources still supports acceleration. Geraint Lewis of the University of Sydney noted that differing interpretations of evidence are common at the frontier of science.