Maybe Dark Matter Is All Just a Big Mistake
A unified theory will deepen our understanding of gravity, which is the only fundamental force of nature that theorists have not yet reconciled with quantum mechanics. In so doing, it might conceivably account for the galactic motions that we now ascribe to dark matter and dark energy. The word “quantum” is commonly taken to mean “small,” and indeed conventional wisdom holds that quantum gravity becomes important only over microscopic distances or under extreme conditions, such as in the interiors of black holes. But some physicists suggest that quantum gravity might show up on large scales as well — either because microscopic effects can accumulate over vast distances of billions of light years, or because the theory entails such dramatic changes in how gravity works that it has exotic consequences for galaxies and larger structures.