Equations of motion when masses move according to Newton's law of gravity. In general relativity, rotational motion is described by the relativistic angular momentum tensor, including the spin tensor, which enter the equations of motion under covariant derivatives with respect to proper time. The Mathisson–Papapetrou–Dixon equations describe the motion of spinning objects moving in a gravitational field. Unlike the equations of motion for describing particle mechanics, which are systems of coupled ordinary differential equations, the analogous equations governing the dynamics of waves and fields are always partial differential equations, since the waves or fields are functions of space and time. For a particular
Three Laws of Robotics letter and spirit they have some similarities with Asimov's Three Laws. They are: These particular laws allow Robocop to harm a human being in order to protect another human, fulfilling his role as would a human law enforcement officer. The classified fourth directive keeps him from arresting any senior OCP officer, effectively putting OCP management above the law. The plot of the film released in 2004 under the name, "I, Robot" is "suggested by" Asimov's robot fiction stories and advertising for the film included a trailer featuring the Three Laws followed by the aphorism, "Rules were made to be broken".