![\"A](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/12\/A-brief-schematic-diagram-of-the-origin-and-evolution-of-the-universe-according-to-the-standard-cosm.webp\")
A brief schematic diagram of the origin and evolution of the universe according to the standard cosmological model \u039bCDM. Credit: Astronuclphysics<\/p>\nFor over two decades, cosmologists have believed that the universe is expanding at an accelerating pace, driven by a mysterious force called dark energy. This assumption has shaped modern theories of cosmic evolution and underpinned the prevailing model of the universe: \u039bCDM. But a striking new study is now challenging that foundational idea.<\/p>\n
Researchers at Yonsei University in South Korea have identified a significant bias in the way astronomers measure cosmic expansion using type Ia supernovae, the stellar explosions long considered \u201cstandard candles.\u201d Their analysis shows that these supernovae are not as uniform as previously assumed\u2014their brightness varies depending on the age of their host galaxies.<\/p>\n
A brief schematic diagram of the origin and evolution of the universe according to the standard cosmological model \u039bCDM. Credit: Astronuclphysics<\/p>\n
This age-dependent brightness skews measurements of cosmic distances, particularly at high redshifts where younger galaxies dominate. Correcting for this bias, the researchers found no evidence of an accelerating universe. In fact, the data suggest that the expansion <\/a>may already be slowing down.<\/p>\n Supernovae May Not Be So Standard After All<\/p>\n For decades, type Ia supernovae have played a critical role in measuring the universe\u2019s expansion rate. Their peak brightness <\/a>was believed to be consistent regardless of where or when they occurred, allowing astronomers to use them to estimate how far away a galaxy is. The further away, the dimmer the explosion appears.<\/p>\n This assumption formed the basis of the 1998 discovery that the universe\u2019s expansion was accelerating\u2014a breakthrough that led to the 2011 Nobel Prize in Physics.<\/p>\n But in this new research, published in the Monthly Notices of the Royal Astronomical Society<\/a>, led by Dr. Chul Chung and Junhyuk Son, the team analyzed over 300 supernova-hosting galaxies and found a clear correlation: the younger the galaxy, the dimmer its supernovae. Distant galaxies, which are typically younger, therefore produce explosions that appear fainter\u2014not necessarily because they are farther away, but because of this age effect.<\/p>\n When this progenitor age bias was accounted for, the apparent evidence for accelerated expansion vanished. The findings suggest that much of what has been interpreted as dark energy\u2019s influence could in fact be the result of uncorrected stellar evolution effects.<\/p>\n This isn\u2019t an isolated claim. Separate observations from the Dark Energy Survey (DES), which examined 16 million galaxies, have already shown tension with the \u039bCDM model. In combining baryon acoustic oscillation (BAO) measurements and supernova data, DES scientists found potential signs that dark energy may not be constant<\/a>.<\/p>\n Dr. Santiago Avila, a researcher involved in the DES BAO analysis, said in that report: \u201cWe can observe the cracks in \u039bCDM, which is considered the standard model of cosmology.\u201d<\/p>\n An Evolving Dark Energy Model Gains Ground<\/p>\n![\"Correlation](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/12\/Correlation-between-SN-Ia-Hubble-residuals-and-host-galaxy-population-age-using-updated-age-measurem.webp\")
Correlation between SN Ia Hubble residuals and host-galaxy population age using updated age measurements. Both the low-redshift R19 sample and the broader G11 sample show a consistent trend: older hosts produce brighter SNe Ia after standardization, confirming the universality of the age bias. Credit: Chung et al. 2025<\/p>\n
![\"Hubble](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/12\/Hubble-image-of-the-famous-Type-Ia-supernova-1994D-in-the-galaxy-NGC-4526.jpeg.webp.webp\")
Hubble image of the famous Type Ia supernova 1994D in the galaxy NGC 4526. This may not be as common anymore. Credit: NASA\/ESA, the Hubble Key Project team, and the High Redshift Supernova Research Team<\/p>\n