Gravitational waves are disturbances in the space-time metric and are caused by the motion of mass in the universe. They are a consequence of Einstein’s General Relativity, but Einstein himself suggested that they were too small to ever be detected. A number of experiments across the globe are aiming to prove him wrong on that account, while at the same time confirming General Relativity.
Ground-based experiments (operational)
Ground-based experiments (proposed)
Space-based experiments (planned and proposed)
Pulsar Timing Arrays