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Largest-Ever Cosmic Test Finds Gravity Falls With Distance as Theory Predicts

The team read tiny shifts in the universe’s oldest light to track how galaxy clusters pull on each other.

Overview

  • Researchers using the Atacama Cosmology Telescope reported in Physical Review Letters that measurements across intergalactic distances match Newton’s inverse‑square law and general relativity.
  • The study tapped the kinematic Sunyaev–Zel'dovich effect, where CMB photons scatter off hot gas in moving clusters, to extract the clusters’ motions from faint imprints in the cosmic microwave background.
  • Analysis of hundreds of thousands of cluster pairs separated by tens to hundreds of millions of light‑years showed no flattening of gravity’s fall‑off.
  • The results undercut modified‑gravity ideas such as MOND at these scales and strengthen the need for unseen dark matter, while leaving its particle identity unresolved.
  • The collaboration of more than 40 researchers says sharper CMB maps and larger galaxy surveys will tighten these tests and could further pin down how dark matter shapes cosmic structure.