Dark matter’s hidden force weakens gravity, slowing cosmic structure growth

Astronomers have uncovered evidence that dark matter particles may interact through an additional, previously unrecognized force. The new study shows that this hidden attraction can pull the particles together, promoting the formation of dense clumps in the early Universe. However, the same interaction also causes dark matter to behave as if it were lighter over cosmological timescales, reducing its overall gravitational pull.

The weakening of dark matter’s effective mass means that, as the Universe expands, its ability to seed the growth of galaxies and large‑scale structures diminishes. Consequently, the hidden force would slow the rate at which cosmic structures develop, counteracting the usual expectation that extra attraction would accelerate clustering. This finding challenges conventional models of structure formation and suggests that dark matter’s role in shaping the cosmos may be more complex than previously thought.

If confirmed, the results will prompt a re‑evaluation of dark matter’s influence on the evolution of the Universe. Researchers will need to incorporate this hidden force into cosmological simulations to better match observations of galaxy distribution and the cosmic web. The discovery underscores the importance of exploring non‑standard interactions in the dark sector to fully understand the dynamics of the cosmos.