A new study published in Monthly Notices of the Royal Astronomical Society suggests that the universe’s expansion may have started to slow down rather than accelerate at an ever-increasing rate, casting doubt on the long-standing theory of dark energy. The researchers used type Ia supernovae and other data to analyze the effects of dark energy on distant galaxies.
According to Professor Young-Wook Lee, lead researcher, “Our study shows that the universe has already entered a phase of decelerated expansion at the present epoch, and that dark energy evolves with time much more rapidly than previously thought.”
The team found that type Ia supernovae, long regarded as the universe’s “standard candles,” are strongly affected by the age of their progenitor stars. This effect was corrected for and showed that the supernova data no longer matched the standard ΛCDM cosmological model with a cosmological constant.
Instead, the analysis aligned far better with a new model favored by the Dark Energy Spectroscopic Instrument (DESI) project, derived from baryonic acoustic oscillations (BAO) and cosmic microwave background (CMB) data. The corrected supernova data combined with BAO and CMB results ruled out the standard ΛCDM model with overwhelming significance.
The researchers also found that if confirmed, their findings would mark a major paradigm shift in cosmology since the discovery of dark energy 27 years ago.
Source: https://ras.ac.uk/news-and-press/research-highlights/universes-expansion-now-slowing-not-speeding