One of the biggest mysteries in science—dark energy—might not exist after all.
This surprising idea comes from researchers at the University of Canterbury in New Zealand, who have been studying how the universe is expanding.
Their work suggests that dark energy, often thought to be a mysterious force pushing the universe apart, might not be needed to explain the way the cosmos grows.
For over 100 years, scientists have believed the universe expands evenly in all directions.
When they noticed galaxies moving away from each other faster than expected, they introduced dark energy to explain the acceleration.
However, this theory has always had its challenges.
Using improved data from exploding stars called supernovae, the New Zealand team has found that the universe’s expansion isn’t uniform—it’s more “lumpy” and varied.
This supports a new idea called the “timescape model,” which doesn’t need dark energy to explain the universe’s behavior.
Here’s how it works: the timescape model takes into account how gravity affects time. In areas like galaxies, where gravity is strong, time moves slower compared to vast, empty spaces known as cosmic voids.
For example, a clock in our Milky Way ticks about 35% slower than one in these voids. Over billions of years, these differences could make it look like space is expanding faster in some regions than in others.
Professor David Wiltshire, who led the study, explains: “Dark energy isn’t needed. The uneven stretching of light we see is because of how time and distance are measured, not because the universe is accelerating everywhere.”
This new approach could also help solve other puzzles about the cosmos.
One such mystery is the “Hubble tension,” where the rate of the universe’s current expansion doesn’t match what we know about its early expansion from the Big Bang’s afterglow, called the Cosmic Microwave Background (CMB).
Adding to the confusion, recent findings from the Dark Energy Spectroscopic Instrument (DESI) suggest that dark energy might not be constant over time, as the current standard model of the universe (called ΛCDM) assumes.
Instead, it could be evolving or not even exist at all.
The timescape model could explain these mismatches better than traditional models. To test it further, new data from advanced space telescopes like the European Space Agency’s Euclid satellite and NASA’s Nancy Grace Roman Space Telescope will be crucial. These missions aim to collect thousands of supernova observations to reveal more about cosmic expansion.
In 2017, the timescape model was only slightly better than the ΛCDM model. But now, thanks to more accurate data from over 1,500 supernovae, the researchers say there is “very strong evidence” supporting their approach.
If confirmed, this new way of thinking could transform how we understand the universe and its expansion.
The race is on to gather more data and finally answer one of science’s biggest questions: does dark energy truly exist, or is it just a misunderstanding of the cosmos?
Source: Royal Astronomical Society.
