As the world turns, II



As a sequel to the saga “As the World Turns” [Chao, 1985], which strolls through the kinematics of the Earth's rotation, this episode relates a close encounter of the dynamic kind with our turning world. First, this article elucidates the distinction between relative and absolute rotations. Then it argues that the instruments that respond to absolute rotation with sufficient sensitivity can potentially detect the Earth's rotational variations under certain conditions; hence, the instruments are complementary and present interesting alternatives to conventional geodetic techniques that measure relative rotation.