We might be very wrong about the expansion of the universe, according to a new paper.
For decades, astronomers have believed that the expansion of the universe is accelerating. Apparent proof of that fact has been around for years, and won the 2011 Nobel Prize in physics.
But a new study suggests that belief might be wrong. The expansion of the universe is actually slowing, scientists have suggested.
The findings are dramatic for our understanding of the cosmos, and are already proving controversial. In the same journal that the new research was published, it was accompanied by another paper from colleagues who disputed the claim.
But the scientists behind the shock new findings say that they are the result of a mistake in taking account of key facts about the way we measure the expansion of the universe.
For more than 25 years, astronomers have been using a collection of exploding stars to measure the universe’s expansion. A dataset known as Pantheon+ includes more than 1,700 of those Type Ia supernovae, and is central to astronomers’ work.
But the new research saw scientists return to that dataset, with a recent proposal that suggests it needs to be corrected by taking into account how old those stars were when they exploded. They also examined whether the expansion rate was the same in all directions, as it is believed it is.
They found that, with the corrections, the data suggests the expansion of the universe is not accelerating uniformly. And it suggests that, overall, it is slowing down rather than speeding up.
Scientists hope to put the new findings to the test using the Rubin Observatory’s Legacy Survey of Space and Time. That will take a huge timelapse of the night sky, over the course of ten years, and allow researchers to examine hundreds of thousands more supernovae.
The work is reported in a new paper, ‘Pantheon + supernovae corrected for progenitor age indicate the universe is decelerating’, published in the journal Monthly Notices of the Royal Astronomical Society.
