Cosmic Gravity Test Strengthens Case for Dark Matter Over Modified Gravity Theories

USC physicists testing gravity on cosmic scales found that it behaves exactly as general relativity predicts, strengthening the case that dark matter is real and weakening alternative theories that propose modified gravity as an explanation for unseen mass. The measurements compared galaxy motion and cosmic-microwave-background observations at scales impossible to reach in laboratory experiments. The result pushes cosmologists closer to a consensus that roughly 85% of universe's matter is some as-yet undetected particle or field, underscoring how much of physical reality remains beyond direct observation even as precision measurements continue to confirm Einstein's century-old framework.