Gravity Remains the Dominant Force Governing Dark Matter, New Study Confirms – But a fifth Force Isn’t Ruled Out
A recent study has provided a robust confirmation of gravity’s dominance in governing the behavior of dark matter, while concurrently leaving open the possibility of a yet-undetected “fifth force” acting on the enigmatic substance. Researchers compared the movement of galaxies through the universe with the gravitational pull of the massive structures they encounter, finding no evidence of deviations that would suggest an additional force at play.
The universe’s largest structures - galaxies, galaxy clusters, and dark matter halos – create significant “gravitational wells” in the fabric of space-time. Ordinary matter naturally accumulates within thes wells, following the principles of Euler’s equations and general relativity. The research team sought to determine if dark matter, which constitutes a large portion of galaxies, behaves in the same manner.
“If dark matter only obeys gravity, then it will behave exactly like ordinary matter,” explained Camille Bonvin, a researcher involved in the study. The team hypothesized that if another force influenced dark matter, even a weak one, it would alter the way galaxies fall into these gravitational wells.
The study utilized precise velocity measurements of galaxies obtained through observations from the DESI (Dark Energy Spectroscopic Instrument) collaboration.By comparing these velocities to the depth of the gravitational wells, researchers were able to assess whether dark matter’s behavior aligned with expectations based solely on gravity.
The results were clear: dark matter appears to fall into gravitational wells in the same way as visible matter, reinforcing the validity of current gravitational models on a cosmological scale. However, the study doesn’t entirely dismiss the possibility of new physics. The analysis indicates that any fifth force, if it exists, can represent no more than 7% of the intensity of gravity.
“A stronger force would have already left an observable signature in our data,” specified nastassia Grimm, first author of the study and a researcher at the University of Portsmouth.
While this research offers a rare experimental confirmation of the robustness of existing gravitational theory, it also underscores the continuing mystery surrounding dark matter – its effects are observed, but it remains unobserved directly.
Looking ahead, upcoming observational instruments like the LSST (Legacy Survey of Space and Time) and continued data from DESI promise to refine our understanding. ”This future data will be sensitive to forces up to 2% of gravity,” explained Isaac Tutusaus, a co-author of the study and researcher at the University of Toulouse. “This could allow us to detect, or definitively exclude, the existence of a fifth cosmic force.”
The confirmation of a fifth force would represent a revolutionary shift in our understanding of the universe, comparable to Einstein’s theory of relativity in 1915. Even without such a discovery, each new measurement contributes to a more nuanced understanding of dark matter and the fundamental laws governing the cosmos.
