According to new research, the expansion of the universe continues to accelerate under the influence of dark energy, despite recent claims to the contrary. This means that dark energy, the mysterious force that dominates the universe, is not weakening but continues to strengthen, which is considered a kind of “cosmological crisis” since it went against expectations.
In 1998, by studying cosmic explosions called Type Ia supernovae, astronomers discovered that not only is the universe expanding, but the speed of that expansion is increasing. “Dark energy” was the name given to the mysterious force driving this accelerated expansion. Scientists have since discovered that dark energy accounts for about 70% of the matter and energy in the universe.
In November 2025, research was published suggesting that the expansion of the universe was slowing, which meant that dark energy would be weakening. But this new research suggests that these findings from last year might not be a cosmic hand grenade thrown onto the cosmological apple cart, but may actually have arisen from a scientific misunderstanding.
“Fortunately, we have avoided this crisis, but the mystery of why the expansion rate of the universe continues to accelerate,” lead author of the new research, Phil Wiseman, of the University of Southampton in the United Kingdom, said in a statement. “Previous, well-accepted measurements were, in fact, correct, and our current understanding of the fate of the universe remains strong. By proving that our measurements are correct, we can get back to trying to understand what this dark energy really is, rather than wondering if it exists.”
The 2025 research that suggested dark energy was weakening was based on a reassessment of the brightness of Type Ia supernovae, which occur when a dead star called a white dwarf supercharges a companion star. This causes a runaway nuclear explosion of such uniform brightness that it can be used to measure cosmic distances. In fact, these bursts are so uniform that astronomers refer to them as “standard candles.”
This earlier research determined, now apparently incorrectly, that as the universe aged, the brightness of Type Ia supernovae had changed, leading to incorrect measurements of distances based on them, as well as incorrect estimates of the universe’s expansion rate. Both led to the suggestion that dark energy is weakening.
But Wiseman and his colleagues discovered that this earlier team had made a mistake when calculating the ages of exploding white dwarfs, discovering that they had assumed that the ages of these stars would be the same as the ages of the galaxies in which they exploded.
They also found that the 2025 research had not taken into account a common correction used in cosmology that takes into account the masses of galaxies in which type Ia supernovae occur.
“Extraordinary claims require especially careful testing,” said team member Adam Riess, who in 2011 shared the Nobel Prize for the discovery of dark energy. “What we found is that when we calibrate these supernovae, taking into account different environments and host populations, the evidence for cosmic acceleration remains remarkably consistent.”
While the challenge to dark energy’s growing dominance over the universe appears to have been refuted, the back-and-forth on this topic shows how ideas in science are not dogma and remain open to revision.
“That’s how progress is made,” said team member Mark Sullivan, also from the University of Southampton. “Although this idea did not turn out to be correct, it opened up new ways of thinking about how supernovae explode and how we can measure dark energy more accurately.”
The team’s research was published June 10 in the journal. Monthly Notices of the Royal Astronomical Society.
