It’s a common refrain in the scientific community. The universe is expanding and accelerating. A study from Yonsei University suggests that the gospel might be wrong.Led by astronomer Young-Wook Lee, the team argues that the supposed “acceleration” is an illusion. Their paper, published in the Monthly Notices of the Royal Astronomical Society, claims that when you factor in the age of the stars used to measure cosmic distances, the data tells a very different story.According to Lee, the universe actually started slowing down about 1.5 billion years ago. If true, that means we’re not hurtling toward a cold, stretched-out death; we might be headed for a “big crunch,” where everything collapses back in on itself.The Universe May Not Be Speeding Up After All, New Research SaysType Ia supernovae have long been treated like cosmic measuring sticks. Astronomers assumed that all stellar explosions shine with the same intrinsic brightness. The fainter a supernova appears, the farther away it must be. But Lee’s team used data from 300 galaxies to show that the brightness of these supernovae depends on the age of the stars that produce them. Older systems make dimmer explosions—and that subtle shift, the researchers say, throws off the entire “accelerating universe” narrative.“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,” Lee said, suggesting that dark energy might not be a constant at all, but something that evolves. If he’s right, he thinks it could be one of the biggest shake-ups in cosmology since dark energy itself was first proposed in the late ’90s.There are naysayers, of course. There are bound to be when anyone confidently offers up a counterargument to one of the most steadfast theories in all of astrophysics. Speaking with The Guardian, cosmologist Carlos Frenk of the University of Durham said of the theory, “It’s definitely interesting. It’s very provocative. It may well be wrong.”Such is the beauty of science. A scientific upstart could upend a long-held theory. Or, as often happens, the upstart didn’t dot all their Is and cross all their Ts and may have overlooked an important bit of data that dispels their own research. Who knows what the future will bring when it comes to our understanding of the universe’s expansion? But it will be fun to watch researchers from across the world try to figure it out.The post The Universe Might Be Slowing Down. What Does That Mean? appeared first on VICE.