Scientists have made a significant advancement in understanding dark matter, revealing that it behaves much like ordinary matter under certain cosmic conditions. A study conducted by researchers from the University of Geneva and other collaborating institutions indicated that dark matter follows familiar physical laws as it interacts with gravitational wells across the universe.
The findings, published on November 16, 2025, in the journal Nature Communications, address a long-standing question in cosmology: whether dark matter adheres to the same principles that govern visible matter. Despite being invisible and challenging to study directly, this research suggests that dark matter may not only conform to known physical forces but could also be influenced by a potential hidden fifth force that remains unidentified.
Investigating Gravitational Interactions
To explore the behavior of dark matter, the UNIGE-led research team examined how it moves through gravitational wells—regions where massive celestial bodies distort the fabric of space. These wells shape the motion of ordinary matter, including planets, stars, and galaxies, based on established theories like Einstein’s general relativity and Euler’s equations. The researchers aimed to determine whether dark matter sinks into these wells similarly to ordinary matter.
Camille Bonvin, an associate professor in the Department of Theoretical Physics at UNIGE and co-author of the study, explained the methodology: “We compared the velocities of galaxies across the Universe with the depth of gravitational wells. If dark matter is not subject to a fifth force, galaxies, which consist mostly of dark matter, will fall into these wells like ordinary matter, governed solely by gravity.”
Insights and Future Directions
The team found that dark matter behaves consistently with Euler’s equations, indicating that it moves into gravitational wells akin to ordinary matter. However, Nastassia Grimm, the study’s first author and a former postdoctoral researcher at UNIGE, cautioned that the presence of a fifth force cannot be entirely dismissed. “If such a force exists, it cannot exceed 7% of the strength of gravity; otherwise, it would have been detected in our analyses,” she noted.
These findings mark a pivotal step in refining our comprehension of dark matter’s role in the cosmos. The next phase of research aims to uncover whether a subtle fifth force is indeed influencing dark matter. According to Isaac Tutusaus, a researcher at ICE-CSIC and co-author of the study, upcoming experiments like the Legacy Survey of Space and Time (LSST) and the Distant Exploration Survey Instrument (DESI) are expected to shed further light on this matter. “These experiments will be sensitive to forces as weak as 2% of gravity, allowing us to learn even more about dark matter’s behavior,” Tutusaus stated.
As scientists continue to unravel the mysteries surrounding dark matter, each new discovery brings humanity closer to understanding the fundamental forces that shape our universe.
