The universe is still expanding faster and faster, according to a new study.
Astronomers have confirmed that cosmic acceleration is continuing, following a University of Southampton-led study using supernova data to challenge claims made in late 2025 that the universe’s expansion was no longer accelerating due to faulty measurements.
Those earlier claims cast doubt on the existence of dark energy, the mysterious force driving the universe apart.
Dr Phil Wiseman, lead author of the Southampton study, said: “The previous and well accepted measurements were, in fact, fine and our current understanding of the fate of the universe remains robust.
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Stars at the centre of the Milky Way galaxy, via the Spitzer Space telescope – credit NASA, JPL-Caltech, S Stolovy (SSCCaltech) (Image: NASA, JPL-Caltech, S Stolovy (SSCCaltech))
“Thankfully we have averted this crisis, but the mystery about why the universe is still accelerating in size remains.
“By proving our measurements are correct, we can get back to trying to understand what dark energy actually is, rather than wondering if it exists at all.”
The study, published in the Monthly Notices of the Royal Astronomical Society, involved Nobel Prize-winning astrophysicists Professor Adam Riess and Professor Brian Schmidt.
Their discovery of the universe’s accelerating expansion won the Nobel Prize in Physics in 2011.
The 2025 challenge suggested these supernovae had varying intrinsic brightness over time, creating the illusion of acceleration.
However, the Southampton-led team found flaws in this analysis.
They showed that the previous claims incorrectly assumed the age of a galaxy matched the age of the exploding star, and failed to account for host galaxy mass, a standard correction in cosmology.
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Lead author Dr Phil Wiseman from the University of Southampton (Image: University of Southampton)
Professor Mark Sullivan from the University of Southampton said: “This is how progress is made.
“Although this idea did not turn out correct, it has opened up new ways of thinking about how supernovae explode and how we can measure dark energy more accurately.”
Co-author Dr Brodie Popovic added: “We’ve recently been really focused on astrophysics of the explosions and how they impact cosmology.
“This was a good opportunity to go back and go over all of our assumptions—it turns out, yes, we do understand this stuff and we’re accounting for it in our cosmology measurement.”