Scientists have made significant strides in understanding dark matter, revealing that it behaves similarly to ordinary matter under specific conditions. A team from the University of Geneva (UNIGE) conducted a study published in Nature Communications, demonstrating that dark matter moves through gravitational wells in a manner consistent with established physical laws. This finding suggests that dark matter may follow the same rules that govern the behavior of visible matter, although the possibility of an undiscovered fifth force remains.
The research addresses a fundamental question in cosmology: does dark matter adhere to the same physical principles as the matter we can observe? Dark matter, which is estimated to constitute approximately five times more mass than ordinary matter, does not emit or reflect light, making it particularly challenging to study directly. By analyzing the motion of galaxies within cosmic structures, the researchers aimed to determine whether dark matter’s behavior aligns with known forces.
To investigate, the UNIGE team compared the velocities of galaxies with the depths of gravitational wells they inhabit. These wells are formed by massive objects that distort the fabric of space, causing matter—both ordinary and dark—to fall into them. According to Camille Bonvin, an associate professor in the Department of Theoretical Physics at UNIGE, “If dark matter is not subject to a fifth force, then galaxies—which are mostly made of dark matter—will fall into these wells like ordinary matter, governed solely by gravity.”
The findings indicated that dark matter behaves according to Euler’s equations, which describe how matter interacts with gravity in these environments. The research suggests that dark matter’s movement mirrors that of ordinary matter, which adds a layer of understanding to its role in the universe. Nevertheless, the team did not entirely rule out the existence of an unknown force. Nastassia Grimm, the study’s first author, stated, “If such a fifth force exists, it cannot exceed 7% of the strength of gravity—otherwise it would already have appeared in our analyses.”
As scientists continue to explore the universe’s mysteries, this research marks a crucial step toward refining our understanding of dark matter and its interactions. The next phase of investigation will focus on determining whether an elusive fifth force influences dark matter. Isaac Tutusaus, a researcher involved in the study, emphasized the importance of upcoming experiments, stating that new data from projects like LSST and DESI will help scientists detect forces as subtle as 2% of gravity.
The revelations from this study not only enhance our grasp of dark matter but also open new avenues for research in cosmology. By continuing to probe the nature of this invisible substance, scientists hope to shed light on the fundamental workings of the universe and our place within it.
