Gravity is supposed to be the most familiar force in nature, yet at the deepest level it remains the least understood. A bold new line of research now argues that gravity is not fundamental at all, ...

Several physicists have proposed theories that try to unite quantum mechanics with Einstein’s general theory of relativity.

Kyoto, Japan -- Einstein was no stranger to mathematical challenges. He struggled to define energy in a way that acknowledged both the law of energy conservation and covariance, which is general ...