Recent research has confirmed that dark matter, a significant yet enigmatic component of the universe, adheres to the laws of gravity on large scales, potentially ruling out the existence of a fifth fundamental force of nature. This breakthrough, reported by a team from the University of Geneva, sheds light on dark matter’s interactions and its role in the cosmos.
Dark matter, which constitutes about 85% of the universe’s total mass, has long puzzled scientists. Unlike ordinary matter, which consists of atoms comprising protons, neutrons, and electrons, dark matter does not interact with electromagnetic radiation, making it nearly invisible. Its presence is inferred primarily through its gravitational effects on visible matter, such as galaxies.
Unveiling the Nature of Dark Matter
Understanding whether dark matter follows the same gravitational principles as ordinary matter is crucial. To investigate this, researchers aimed to determine if dark matter behaves similarly to ordinary matter by falling into cosmic gravity wells—a phenomenon predicted by Albert Einstein‘s theory of general relativity.
“To answer this question, we compared the velocities of galaxies across the universe with the depth of gravitational wells,” said Camille Bonvin, a researcher involved in the study. “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 only by gravity.” This comparison is vital to understanding the potential impact of a fifth force on dark matter’s motion.
Using up-to-date cosmological data, the research team found that dark matter does indeed behave like ordinary matter, slipping into gravity wells created by massive cosmic bodies. While these findings do not definitively rule out the existence of a fifth fundamental force, they suggest that if such a force exists, it cannot exceed 7% of the strength of gravity, otherwise it would have been evident in their analysis.
Implications for Future Research
“At this stage, these conclusions do not yet rule out the presence of an unknown force,” explained Nastassia Grimm, team leader and researcher at the University of Portsmouth. “But the data indicates that if a fifth force does exist, it is weak.” This research provides a framework for understanding dark matter’s characteristics and its interactions in the universe.
Future studies may reveal even more about dark matter’s behavior. Upcoming data from advanced experiments, including the Legacy Survey of Space and Time conducted by the Vera C. Rubin Observatory and the Dark Energy Spectroscopic Instrument (DESI), are expected to be sensitive to forces as weak as 2% of gravity. “These findings should allow us to learn even more about the behavior of dark matter,” noted Isaac Tutusaus, a researcher at the University of Toulouse.
This study was published on November 3, 2023, in the journal Nature Communications, marking a significant step forward in our understanding of dark matter and its potential interactions with fundamental forces in the universe.
