Key points: A Nature paper from research teams in Switzerland and Spain finds that galaxy motions are consistent with dark matter obeying gravity, reducing the likelihood of a distinct "fifth force." The study sets an upper limit on any extra force at about 7% of gravity's strength. The authors stress this is a constraint, not a categorical exclusion, and say upcoming higher-precision data could test down to roughly 2%.
New Nature Study Finds Dark Matter Follows Gravity — Weakens Case for a 'Fifth Force'
Key points: A Nature paper from research teams in Switzerland and Spain finds that galaxy motions are consistent with dark matter obeying gravity, reducing the likelihood of a distinct "fifth force." The study sets an upper limit on any extra force at about 7% of gravity's strength. The authors stress this is a constraint, not a categorical exclusion, and say upcoming higher-precision data could test down to roughly 2%.
03:55, 07.11.2025Science
Dark matter appears to obey gravity, researchers report
A new study published in Nature by teams in Switzerland and Spain examines the large-scale distribution and motion of dark matter to test whether it responds to the same gravitational laws as ordinary matter. The authors find no strong evidence that dark matter is driven by an additional, exotic "fifth force," and place an upper limit on any such force at roughly 7% of gravity's strength.
Physicists typically describe interactions in the universe using four fundamental forces—electromagnetism, the strong and weak nuclear forces, and gravity. For decades, however, some cosmic observations have motivated proposals that certain components of the universe might feel a separate interaction visible only on astronomical scales. Dark matter has often been a candidate for such a nonstandard force.
The research team compared observed galaxy motions with predictions for how visible (baryonic) matter should move if dark matter were subject only to gravity. According to the paper, the visible components of galaxies move in a way consistent with gravitational influence from the surrounding dark matter. If dark matter experienced a distinct fifth force, the authors explain, the motions of visible and dark components would show a detectable mismatch.
Visualizations: Dark matter maps commonly depict a vast, filamentary "cosmic web" connecting galaxies and clusters across the universe.
Nastassia Grimm, the study's lead author, told Space.com: "At this stage... these conclusions do not yet rule out the presence of an unknown force. But if such a fifth force exists, it cannot exceed 7% of the strength of gravity—otherwise it would already have appeared in our analyses."
The researchers emphasize that this result is an upper limit rather than a definitive disproof: smaller non-gravitational effects could still exist below the current sensitivity. They also note that forthcoming, higher-precision surveys and experiments may be able to test for forces as weak as about 2% of gravity, further constraining or potentially revealing subtle deviations.
Takeaway: The study tightens constraints on exotic forces acting on dark matter and strengthens the view that dark matter behaves gravitationally on large scales, while leaving room for very weak additional interactions that future data could probe.