Physicists are increasingly exploring the idea that dark energy and dark matter, long treated as separate cosmic mysteries, may in fact be linked or even manifestations of a single "dark sector" theory. The renewed interest follows observations from the DESI collaboration in 2024, later reinforced by a larger 2025 study, suggesting that dark energy's strength has not been constant but appears to have peaked roughly two billion years ago before weakening, and may even have grown stronger in an earlier era in an apparent breach of energy conservation, a puzzle researchers call the "phantom regime".

Several teams have proposed models in which dark matter and dark energy exchange energy, which could explain the phantom-like behaviour without violating physical laws. Justin Khoury of the University of Pennsylvania first explored such interactions in 2005 and has since built a new model with colleagues based on a dark-sector analogue of quantum chromodynamics. A separate study published in January in Physical Review D, led by Elsa Teixeira of the University of Montpellier, suggests dark matter may have transferred energy to dark energy in the past, easing its braking effect on cosmic expansion and causing the universe to accelerate faster than expected.