Modified gravity hides in small scales to fix cosmic structure tension

Tensions between how much cosmic structure we observe and what standard cosmology predicts might be resolved by tweaking gravity itself — but only on scales smaller than roughly 10 megaparsecs. Combining Planck, DESI, and supernova data, the authors find that adding scale-limited modifications to gravity on top of a dynamical dark energy background improves the fit to observations enough to move from 'moderate' to 'mildly strong' preference over the standard cosmological model. The result tightens where any departures from general relativity must hide, giving future surveys a concrete target.