Scientists have found possible evidence that Dark Energy, the mysterious force driving the expansion of the Universe, may be changing over time—posing a challenge to established theories of time and space.
Some experts believe they could be on the brink of a groundbreaking discovery—one that might require a fundamental reassessment of our understanding of the cosmos.
This early-stage finding contradicts the prevailing theory, which was partly developed by Albert Einstein. While additional data is needed for confirmation, even highly respected researchers involved in the study, such as Professor Ofer Lahav of University College London, acknowledge the significance of the mounting evidence.
“It is a dramatic moment,” Lahav told BBC News. “We may be witnessing a paradigm shift in our understanding of the Universe.”
A Force That Defied Expectations
The discovery of Dark Energy in 1998 was itself a revelation. Until then, scientists believed that the expansion of the Universe—initiated by the Big Bang—would eventually decelerate under the force of gravity.
However, observations made by US and Australian researchers showed that the Universe was actually expanding at an accelerating rate. They could not identify the force responsible, so they termed it Dark Energy to reflect its unknown nature.
Although the exact nature of Dark Energy remains a mystery, astronomers can measure its effects by analyzing how galaxies move away from each other at different points in the Universe’s history.
To deepen their understanding, researchers developed specialized experiments, including the Dark Energy Spectroscopic Instrument (DESI), located at the Kitt Peak National Observatory in Arizona. This instrument consists of 5,000 robotically controlled optical fibers that rapidly scan galaxies to track cosmic expansion.
Unexpected Findings Gain Strength
Last year, DESI researchers detected hints that Dark Energy’s force might have varied over time. Initially, many scientists dismissed this as a statistical anomaly that would disappear with further data.
However, rather than fading, the anomaly has become more pronounced.
“The evidence is stronger now than it was,” said Professor Seshadri Nadathur of the University of Portsmouth.
“We’ve also performed many additional tests compared to the first year, and they’re making us confident that the results aren’t driven by some unknown effect in the data that we haven’t accounted for,” he added.
“Dark Energy Is Even Weirder Than We Thought”
The findings have yet to reach the threshold of an official scientific discovery, but they have sparked intrigue among leading astronomers.
“Dark Energy appears to be even weirder than we thought,” said Scotland’s Astronomer Royal, Professor Catherine Heymans of Edinburgh University, in an interview with BBC News.
“In 2024, the data was quite new, no one was quite sure of it, and people thought more work needed to be done,” Heymans said. “But now, there’s more data and a lot of scrutiny by the scientific community. So, while there is still a chance that the ‘blip’ may go away, there’s also a possibility that we might be edging toward a really big discovery.”
The source of the apparent variation remains unknown.
“No one knows!” Lahav admitted. “If this new result is correct, then we need to find the mechanism that causes the variation, and that might mean a brand-new theory—which makes this so exciting.”
The Search for More Evidence
DESI will continue collecting data over the next two years, with the goal of analyzing roughly 50 million galaxies and other luminous objects. The aim is to determine whether the observations are undeniably accurate.
“We’re in the business of letting the Universe tell us how it works,” said Andrei Cuceu, a postdoctoral researcher at the Lawrence Berkeley National Laboratory in California. “And maybe it is telling us it’s more complicated than we thought it was.”
Further insights into Dark Energy are expected from the European Space Agency’s (ESA) Euclid mission, a space telescope designed to probe deeper into the Universe with even greater precision. Launched in 2023, Euclid has already begun delivering highly detailed images, which were released by ESA today.
The DESI collaboration includes more than 900 scientists from over 70 institutions worldwide, with notable contributions from researchers at Durham University, University College London, and the University of Portsmouth in the UK.