Scientists have made significant strides in understanding dark matter, revealing that it behaves much like ordinary matter, according to a recent study from the University of Geneva (UNIGE). Through a detailed analysis of galaxy movements within gravitational wells, researchers discovered that dark matter appears to follow established physical laws, although the possibility of an unknown force influencing its behavior remains.
Dark matter, which constitutes approximately five times more mass in the universe than ordinary matter, is notoriously elusive and does not emit or reflect light. The study, published in Nature Communications, aims to determine if dark matter responds to the same fundamental forces that govern visible matter, such as gravity, electromagnetism, and the strong and weak nuclear forces.
Examining Dark Matter’s Movement
The research team led by UNIGE examined how dark matter interacts with gravitational wells—regions where massive objects warp space-time, pulling in surrounding matter. Traditional matter, including stars and planets, falls into these wells according to well-established physical principles.
Camille Bonvin, an associate professor in the Department of Theoretical Physics at UNIGE and co-author of the study, explained, “To answer this question, 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, then galaxies—mostly composed of dark matter—will fall into these wells like ordinary matter, governed solely by gravity.” This comparison allows researchers to examine whether dark matter behaves in a predictable manner or if it is influenced by additional forces.
The findings indicate that dark matter does indeed sink into gravitational wells similarly to ordinary matter, aligning with Euler’s equations. This suggests that dark matter adheres to the same physical laws that govern visible matter, although the researchers caution that their findings do not entirely rule out the presence of a previously unidentified force.
Implications of the Research
Nastassia Grimm, the study’s first author and former postdoctoral researcher at UNIGE, noted that if a fifth force exists, it must be exceptionally weak, not exceeding 7% of the strength of gravity. “Otherwise, it would already have appeared in our analyses,” she stated.
These early findings mark a crucial advancement in the ongoing quest to understand dark matter. The next objective for researchers is to explore whether a subtle fifth force influences dark matter’s behavior. Upcoming data from experiments like the Large Synoptic Survey Telescope (LSST) and the Dark Energy Spectroscopic Instrument (DESI) are expected to provide further insights into this mystery. These experiments are capable of detecting forces as weak as 2% of gravity, potentially shedding light on the hidden complexities of dark matter.
As research continues to evolve, the scientific community remains hopeful that these insights will clarify the fundamental nature of dark matter and its role in shaping the universe. The implications of such discoveries extend beyond theoretical physics, touching on the very fabric of our understanding of the cosmos.
