A cosmic shake-up? New data suggests Dark Energy isn’t constant—astronomers brace for a major revelation

The force driving the Universe’s expansion — Dark Energy — might be changing in ways that defy existing theories, potentially reshaping our understanding of time and space. Some scientists believe they are on the brink of a discovery that could redefine astronomy for a generation.  

This early-stage finding contradicts the widely accepted model developed in part by Albert Einstein. While more data is needed to confirm the results, even the most cautious researchers, such as Professor Ofer Lahav of University College London, acknowledge the growing evidence.  

"It is a dramatic moment," Professor Lahav told BBC News. "We may be witnessing a paradigm shift in our understanding of the Universe."  

The discovery of Dark Energy in 1998 was a shock. Before then, scientists believed the Universe’s expansion, triggered by the Big Bang, would gradually slow due to gravity. Instead, astronomers found that expansion was accelerating. Unable to explain the force behind this, they named it Dark Energy—signifying the vast unknown.  

 

Despite not knowing what Dark Energy is, astronomers can measure its effects by observing how galaxies move apart over time. To do this, they rely on powerful experiments, including the **Dark Energy Spectroscopic Instrument (DESI)** in Arizona, which uses 5,000 optical fibers to scan galaxies at high speed.  

In 2023, DESI researchers noticed a potential shift in Dark Energy’s force — an anomaly many initially dismissed as a data glitch. But instead of disappearing, the anomaly has become stronger.  

The data has yet to reach the threshold of a confirmed discovery, but it’s enough to capture the attention of top astronomers, including Scotland’s Astronomer Royal, Professor Catherine Heymans of Edinburgh University.  

"Dark Energy appears to be even weirder than we thought," she said. "In 2024, no one was sure of the data, and many believed more work was needed. Now, with more scrutiny and data, we might be edging toward a really big discovery."  

What’s behind the change  

Right now, no one knows. "If this new result is correct, we need to find the mechanism causing the variation," Professor Lahav admitted. "That might mean an entirely new theory, which is what makes this so exciting."  

To confirm their findings, DESI will continue collecting data for the next two years, analyzing around 50 million galaxies and other bright objects. Meanwhile, the European Space Agency’s Euclid mission, launched in 2023, will probe even deeper into space to provide further insights.  

For now, astronomers are letting the Universe reveal its secrets. "Maybe it's telling us it's more complicated than we thought," said Andrei Cuceu, a researcher at Lawrence Berkeley National Lab.