For decades, we’ve been told that the universe is speeding away from itself with galaxies drifting apart faster and faster, powered by a mysterious force called dark energy. It sounded like a cosmic runaway story, one that even won a Nobel Prize. But what if that story isn’t quite right?

A new study now claims the universe’s expansion may actually be slowing down, not accelerating. If that’s true, the entire fate of the cosmos could look very different — one that doesn’t end in endless growth, but perhaps in a dramatic cosmic collapse.

Could the Universe be heading towards a "big crunch"?

According to the study, if the universe’s expansion continues to slow, it could one day stop altogether and begin collapsing in what scientists call a “Big Crunch” — the opposite of the Big Bang. This theory suggests that the mysterious force known as dark energy, long thought to be driving cosmic acceleration, might be losing its strength over time.

Professor Young-Wook Lee of Yonsei University in South Korea, who led the research, said the team’s observations show that the universe has already entered a phase of slower expansion. Their results also indicate that dark energy might be changing much more quickly than scientists previously believed.

If confirmed, these findings would represent one of the most significant shifts in cosmology since the discovery of dark energy nearly three decades ago.

Why are scientists divided on this discovery?

The new research is expected to face scepticism from the scientific community. However, similar results were reported earlier this year by another major research group, the Desi Consortium, sparking renewed debate about the true nature of dark energy and the future of the universe.

The study also questions the reliability of earlier measurements based on distant supernovae — the very observations that led to the discovery of dark energy and the Nobel Prize in 2011.

Professor Lee explained that astronomers may have been relying on a false assumption for nearly thirty years. He compared it to fastening the first button of a shirt incorrectly — once that mistake is made, everything that follows is out of place.

What did scientists believe before this?

Before the 1990s, scientists thought that gravity acted like a “cosmic brake,” gradually slowing down the universe’s expansion. That view changed when researchers began studying Type 1a supernovae, which were used as “standard candles” because their light was thought to shine with a consistent brightness.

When astronomers observed that distant supernovae appeared dimmer than expected, they concluded that the universe was expanding faster than before. This finding gave rise to the theory of dark energy — a mysterious force supposedly driving this acceleration.

What does the new evidence show?

The latest study offers an alternative explanation. By analysing 300 host galaxies and estimating their ages using a new technique, Professor Lee’s team found that supernovae formed in the early universe may have been slightly less bright than those seen today.

After adjusting for this difference, the data still supports that the universe is expanding — but not as rapidly as once believed. The results also point towards the possibility that dark energy is weakening. If it eventually becomes negative, the universe could stop expanding and start collapsing inwards, ending in a “Big Crunch.”

How are experts reacting?

Astronomer Professor Carlos Frenk from the University of Durham, who was not involved in the study, described the findings as both interesting and challenging. He said that even if these conclusions turn out to be incorrect, they are still important and cannot be dismissed.