Recent research from the University of Geneva (UNIGE) indicates that dark matter, though invisible, behaves in ways similar to ordinary matter. The study, published on November 16, 2025, investigates how dark matter interacts with gravitational wells in the cosmos, suggesting it adheres to established physical laws.
Dark matter has long puzzled scientists because it does not emit or reflect light, making it exceedingly difficult to study directly. The researchers aimed to determine whether dark matter follows familiar physical principles or if other, unidentified forces might influence it. Their findings suggest that dark matter moves through gravitational wells in a manner akin to ordinary matter, although the possibility of a hidden fifth force remains.
Exploring Dark Matter’s Behavior
The research team, led by Camilie Bonvin, an associate professor in the Department of Theoretical Physics at UNIGE, examined the movement of galaxies in relation to the depth of gravitational wells. Massive cosmic structures distort space, creating these wells, into which both ordinary matter—such as planets and stars—and dark matter fall. The study specifically looked at whether dark matter behaves predictably, similar to how ordinary matter does under the influence of the four known fundamental forces: gravity, electromagnetism, and the strong and weak nuclear forces.
Bonvin explained, “If dark matter is not subject to a fifth force, then galaxies—mostly composed of dark matter—will fall into these wells like ordinary matter, governed solely by gravity.” Conversely, if a fifth force exists, it could alter the expected motion of galaxies significantly.
In their analysis, the researchers compared the velocities of galaxies with the depths of the gravitational wells. The results confirmed that dark matter’s movement aligns with Euler’s equations, which describe the dynamics of fluid motion, indicating it behaves similarly to ordinary matter in these scenarios.
Implications and Future Research
While the findings are promising, they do not eliminate the possibility of an undiscovered force influencing dark matter. Nastassia Grimm, the study’s first author, noted that if a fifth force exists, it must be weaker than 7% of the strength of gravity to have evaded detection in their analyses.
This work marks a significant advancement in our understanding of dark matter, which is estimated to be five times more prevalent than ordinary matter in the universe. Researchers are now looking towards upcoming experiments, such as the Large Synoptic Survey Telescope (LSST) and Dark Energy Spectroscopic Instrument (DESI), to gather data that could detect even weaker forces, potentially as faint as 2% of gravity.
According to Isaac Tutusaus, a co-author of the study, “The next key objective is to determine whether a subtle fifth force truly affects dark matter.” The insights gained from these future investigations could further illuminate the behavior of dark matter and its role in shaping the universe.
This research not only advances our understanding of dark matter but also opens new avenues for exploration in cosmology, enhancing our grasp of the universe’s fundamental components.
