Scientists have established that dark matter, the enigmatic component of the universe, adheres to gravitational laws on a cosmic scale. This discovery could potentially diminish the likelihood of a fifth fundamental force of nature, while also providing insights into the characteristics of dark matter itself. The findings were published on November 3, 2023, in the journal Nature Communications.
Researchers from the University of Geneva (UNIGE) sought to determine whether dark matter behaves under the influence of gravity similarly to ordinary matter. Understanding this relationship is crucial, as dark matter constitutes approximately five times more of the universe’s mass compared to regular matter. The challenge has been that dark matter does not interact with light or electromagnetic radiation in the same way that ordinary matter does, making it largely invisible and detectable only through its gravitational effects.
To test their hypothesis, the researchers compared the velocities of galaxies to the depth of gravitational wells created by massive celestial bodies. According to Camille Bonvin, a member of the research team, “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 only by gravity.”
The study’s methodology involved examining data on how galaxies fall into these gravitational wells. If a fifth force were to influence dark matter, it would alter the motion of galaxies, resulting in different falling patterns compared to ordinary matter.
The results indicated that dark matter does indeed fall into gravity wells in a manner consistent with established gravitational laws. While this finding does not completely eliminate the possibility of a fifth force, it suggests that if such a force exists, it cannot exceed 7% of the strength of gravity. Nastassia Grimm, the team leader from the Institute of Cosmology and Gravitation at the University of Portsmouth, noted, “These conclusions do not yet rule out the presence of an unknown force.”
The implications of this research extend beyond immediate findings. Isaac Tutusaus, a researcher at the University of Toulouse, emphasized that future experiments, including the Legacy Survey of Space and Time conducted by the Vera C. Rubin Observatory and the Dark Energy Spectroscopic Instrument (DESI), will enhance our understanding of dark matter’s behavior. He stated, “They should therefore allow us to learn even more about the behaviour of dark matter.”
These findings offer a clearer framework for understanding the elusive nature of dark matter, setting the stage for ongoing exploration in the field of cosmology. The quest to unlock the mysteries of the universe continues, with researchers poised to investigate the fundamental forces that govern it.
