Research from the University of Geneva (UNIGE) has provided fresh insights into the behavior of dark matter, suggesting it behaves similarly to ordinary matter under gravitational forces. This study, published in Nature Communications on November 3, 2025, aims to clarify whether dark matter is influenced by known physical laws or if it is governed by an unidentified force.
Dark matter, which constitutes approximately five times the amount of ordinary matter in the universe, remains largely enigmatic. It does not emit or reflect light, making it detectable only through its gravitational effects on visible matter. The UNIGE-led team sought to determine if dark matter falls into gravitational wells created by massive celestial bodies in the same manner as ordinary matter does.
Understanding Dark Matter’s Behavior
According to Camille Bonvin, an associate professor in the Department of Theoretical Physics at UNIGE and co-author of the study, “We compared the velocities of galaxies across the universe with the depth of gravitational wells.” The research posits that if dark matter is not influenced by an additional force, galaxies—primarily composed of dark matter—will behave similarly to ordinary matter, governed exclusively by gravity.
The study evaluated how galaxies, under the influence of gravity, fall into these wells, which are areas of space distorted by massive celestial objects. Ordinary matter, including planets and stars, adheres to established physical laws, such as Einstein’s theory of general relativity and Euler’s equations.
Should a fifth, unidentified force act upon dark matter, it would alter how galaxies move within these gravitational wells. The researchers aimed to identify whether any disparities existed in the motion of galaxies compared to what is predicted by existing gravitational models.
Key Findings and Future Implications
The findings indicate that dark matter follows the same gravitational principles as ordinary matter, adhering to Euler’s equations. Yet, the results do not entirely dismiss the existence of a fifth force. According to Nastassia Grimm, the study’s first author and former postdoctoral researcher at UNIGE, “If such a fifth force exists, it cannot exceed 7% of the strength of gravity; otherwise, it would have already been apparent in our analyses.”
These results are considered a significant advancement in understanding dark matter’s properties. The ongoing challenge will be to ascertain whether any additional forces govern its behavior. Future experiments, including the Large Synoptic Survey Telescope (LSST) and Dark Energy Spectroscopic Instrument (DESI), are expected to probe forces as weak as 2% of gravity, potentially yielding deeper insights into dark matter dynamics.
In conclusion, this research not only enhances our comprehension of dark matter but also sets the stage for future investigations that could reshape current cosmological models. As scientists continue to explore the universe’s hidden components, understanding dark matter remains a critical frontier in physics.
