MOND Alternative Theory

Not everyone is convinced dark matter exists. Modified Newtonian Dynamics (MOND), proposed by Mordehai Milgrom in 1983, suggests Newton's laws of gravity break down at very low accelerations. Instead of invisible matter, the rules of physics would change at galactic scales, explaining flat rotation curves on their own.

MOND predicts galaxy rotation curves well but struggles with galaxy clusters, the CMB power spectrum, and the Bullet Cluster. Most physicists favor dark matter, yet MOND's success at the galactic scale keeps it intriguing.