Dark energy under scrutiny as scientists question the leading model of the universe
Scientists have revised the model of the expansion of the universe (Photo: Pexels)
One of the main theories of modern cosmology may turn out to be flawed. New research suggests that the universe may not be expanding uniformly in all directions, as scientists have believed for decades, according to a study published in the scientific journal Monthly Notices of the Royal Astronomical Society.
Scientists explained that Type Ia supernovae have traditionally been used to measure the rate of cosmic expansion. They occur in binary star systems with white dwarfs that either accrete matter from a companion star until reaching a critical mass, or merge with another white dwarf.
Thanks to the predictable brightness of these explosions, astronomers calculate the distance to them, and using redshift, their recession velocity.
The researchers analyzed the Pantheon+ supernova catalog and applied a correction for the age of the progenitor stars, developed by astronomers at Yonsei University.
It turned out that the standard brightness of supernovae depends on the age of the stellar system:
- After the correction, supernovae from younger progenitors were systematically dimmer than those arising from older stars;
- Since more distant supernovae originate from younger stars, they appear dimmer than they actually are;
- This excess dimming creates a false effect of additional distance, mimicking an accelerated expansion of the universe.
As a result, the observed acceleration turned out to be anisotropic — it varies in intensity depending on the direction of observation.
Crisis of the standard model
The researchers identified an anomalous pattern: the effect previously attributed to the accelerated expansion of the universe is strongest in the direction of the Milky Way's motion, and gradually weakens with increasing distance.
If confirmed, this means that one of the central pillars of modern cosmology may be incorrect.
According to the authors, the universe continues to expand, but it is not accelerating as had been believed for decades. On the contrary, the rate of this expansion may be gradually decreasing.
If the findings are confirmed, they would call into question one of the primary models astronomers have used for decades to explain the universe's evolution.
Furthermore, the new work could help resolve the so-called "Hubble tension" — a long-standing problem in which different methods of measuring the expansion rate yield conflicting results.
According to the authors, the data obtained do not confirm that the universe is expanding uniformly in all directions, yet it is precisely on this assumption that modern cosmological models are based.
