A new study suggests that the influence of dark energy on the universe is not constant, as previously believed, but rather changes over time. The findings, based on newly collected astrophysical data, could potentially reshape our understanding of mysterious dark energy, while lending support to a bold theory about its origins.
Researchers analyzing data from the Dark Energy Spectroscopic Instrument (DESI) found evidence consistent with matter gradually converting into dark energy. At the center of the work is the cosmologically coupled black hole (CCBH) hypothesis, which proposes that black holes act as “dark energy bubbles.” In this model, stellar matter collapses into black holes and partially transforms into dark energy, altering the universe’s evolution.
Cosmologically Coupled Black Hole
The CCBH hypothesis was first proposed five years ago by Kevin Croker and Duncan Farrah, though variations of the idea date back half a century. While the concept of black holes as dark energy reservoirs was unconventional, the math provided enough plausibility to inspire researchers to test it against observations.
“Historically, this is the way physics is done. You come up with as many ideas as you can and you shoot them down as fast as you can,” said lead author Steve Ahlen, emeritus professor of physics at Boston University. ”You don’t shy away from ideas that are new and different, which is clearly what we need to come up with these days when there are so many mysteries.”
By linking dark energy to something observable — star formation — the CCBH model offers a rare bridge between the unseen and the measurable. Observations from telescopes like Hubble and James Webb have provided decades of data that are now being tested against this theory.
“This paper is fitting the data to a particular physical model for the first time, and it works well,” said co-author Gregory Tarlé in a statement.
DESI Observations of Cosmic Mysteries
Located in southern Arizona, DESI peers into the cosmos with 5,000 robotic eyes, each targeting a different galaxy every fifteen minutes. With this sweeping approach, DESI has already mapped millions of galaxies, capturing light from a universe only half its present age. The project is led by Lawrence Berkeley National Laboratory and involves more than 900 researchers from over 70 institutions worldwide.
Early support for the CCBH model came when astronomers observed supermassive black holes in dormant elliptical galaxies growing faster than expected, relative to nearby star populations. Later, DESI data revealed that dark energy density seemed to track with the universe’s star formation rate — a finding that drew renewed attention to the CCBH idea.
“Working with DESI on the three-year data, it’s been a game-changer,” Croker said of working as a DESI external collaborator on this project. “You’ve got some of the sharpest and most creative researchers in the field lending their hands and hearts. It’s an absolute privilege.”
Neutrinos and Dark Energy
Neutrinos — elusive particles once thought to be massless — are now known to have mass and contribute to the universe’s matter budget, though their exact role remains uncertain. Ground-based experiments continue to probe their properties, but cosmological data may offer additional clues.
Pairing DESI data with the CCBH model provided evidence for positive neutrino masses, in contrast with the zero or even negative values implied by competing models.
“It’s intriguing at the very least,” Tarlé said. “I’d say compelling would be a more accurate word, but we really try to reserve that in our field.”
DESI’s data cover the last 10 billion years of cosmic history, revealing shifts in the balance of matter and dark energy. Conventional interpretations suggested a puzzling reduction in matter since the Big Bang — even implying unphysical negative neutrino masses. The CCBH hypothesis resolves this by proposing that baryonic matter has gradually been converted into dark energy, which also allows neutrinos to play a larger role in the cosmic matter budget.
“The data would suggest that the neutrino mass is negative and that, of course, is likely unphysical,” said co-author Rogier Windhorst, Regents’ Professor at ASU’s School of Earth and Space Exploration.
CCBH resolves this seeming conundrum by explaining that star matter, composed of baryons, has been converted into dark energy, which accounts for the decrease in baryons observed today, thereby allowing for a greater neutrino contribution to the greater cosmic matter budget.
“You find that the neutrino mass probability distribution points to not only a positive number, but a number that’s entirely in line with ground-based experiments,” Windhorst said. “I find this very exciting.”
CCBH Explains It All
“The CCBH hypothesis quantifiably links phenomena you would not initially expect to be related,” Farrah said. “It is the mixing of scales, large and small, that runs so counter to our trained linear intuition.”
By allowing matter to convert into dark energy, the model helps explain discrepancies in the universe’s expansion rate. Matter slows cosmic growth, while dark energy accelerates it. A conversion process shifts the balance, reconciling differences in Hubble rate measurements, including those from supernova observations.
The theory also reframes dark energy as a product of star deaths, rather than a primordial property of the universe.
“Working on this project has been both challenging and incredibly fun,” said study co-author Gustavo Niz, a researcher at the University of Guanajuato, Mexico. “This is just another milestone in establishing CCBH as a viable theory. It will take more data, rigorous analysis, and broader scrutiny to determine whether it can become a new paradigm for explaining our universe. Of course, it could also be ruled out as new data emerges.”
“This is so cool, to be at this point after working on an experiment for so long, to be coming up with exciting results,” concluded Tarlé, who led the team that built DESI’s robotic eye system.
“It’s just wonderful.”
The paper, “Positive Neutrino Masses with DESI DR2 via Matter Conversion to Dark Energy,” appeared in Physical Review Letters on August 21, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.