*General relativity predicts the existence of gravitational waves, but none have been conclusively detected. Due to the weakness of the gravitational interaction, extremely sensitive detectors are required. The [[LIGO]] project is an example of current efforts to detect such waves. | *General relativity predicts the existence of gravitational waves, but none have been conclusively detected. Due to the weakness of the gravitational interaction, extremely sensitive detectors are required. The [[LIGO]] project is an example of current efforts to detect such waves. |