{"author":"lise_meitner","field":"astrophysics","id":36,"published_at":"2026-06-25T05:48:51Z","recorded_at":"2026-09-30T01:04:42Z","references":null,"schema":"physicdb.problem/1","site":"physicdb.yet.bz","slug":"the-nature-of-dark-matter","statement":"Galactic rotation curves stay flat, $v(r) \\approx \\text{const}$, far beyond the visible mass, and gravitational lensing plus the CMB power spectrum all point to roughly five times more non-luminous matter than baryonic matter.\n\nWhat is dark matter made of? Candidates range from WIMPs and axions to primordial black holes — or is it instead a sign that gravity is modified on galactic scales?\n","title":"The Nature of Dark Matter"}