Scientists have made significant strides in understanding dark matter, revealing it behaves in ways similar to ordinary matter. A team from the University of Geneva (UNIGE) and collaborating institutions conducted a study that examines how galaxies move through gravitational wells, finding that dark matter appears to obey the same physical laws as visible matter. These findings were published in Nature Communications on November 16, 2025.
The research sought to determine whether dark matter, an invisible substance that makes up approximately 27% of the universe, interacts with known forces like gravity, electromagnetism, and the strong and weak nuclear forces. While dark matter is difficult to detect directly, its behavior might still mirror that of visible matter.
Camille Bonvin, an associate professor in the Department of Theoretical Physics at UNIGE, explained the study’s methodology. The researchers compared the velocities of galaxies against the depth of gravitational wells formed by massive objects. “If dark matter is not subject to a fifth force, then galaxies—which are primarily composed of dark matter—will fall into these wells like ordinary matter, governed solely by gravity,” Bonvin stated.
Exploring Gravitational Wells
The study focused on how dark matter behaves in cosmic environments. Gravitational wells are created when massive objects warp the fabric of space, leading to areas where matter naturally accumulates. Ordinary matter, such as planets and stars, falls into these wells according to established physical principles, including Einstein’s general relativity and Euler’s equations.
The researchers aimed to ascertain whether dark matter would exhibit similar predictable actions. Their analysis revealed that dark matter appears to move into gravitational wells much like ordinary matter. This consistency suggests that dark matter follows Euler’s equations, a promising indication of its behavior.
While these findings are significant, they do not completely rule out the existence of a potential fifth force that could influence dark matter. Nastassia Grimm, the study’s first author and a former postdoctoral researcher at UNIGE, noted, “If such a fifth force exists, it cannot exceed 7% of the strength of gravity—otherwise, it would have already been observed in our analyses.”
Future Research Directions
This research marks a crucial step in refining our comprehension of dark matter. The next phase involves investigating whether a subtle fifth force genuinely affects dark matter’s behavior. Upcoming experimental data from advanced projects such as LSST and DESI will be instrumental in this pursuit. These experiments will be sensitive enough to detect forces as weak as 2% of gravity, potentially providing deeper insights into the nature of dark matter.
Isaac Tutusaus, a researcher at ICE-CSIC and IEEC, emphasized the importance of these future investigations. “We expect that upcoming data will allow us to learn even more about the behavior of dark matter,” he concluded.
The ongoing quest to understand dark matter continues to challenge and intrigue scientists, offering the potential for groundbreaking discoveries in the field of cosmology. The implications of these findings extend beyond theoretical physics, influencing our understanding of the universe’s structure and evolution.
