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 a red indicator light." The red light indicated the wireless uplink to the manufacturer is active, first seen during a software update and later on "Evil" robots taken over by the manufacturer's positronic superbrain. In 2013 Hutan Ashrafian, proposed an additional law that for the first time considered the role of artificial intelligence-on-artificial intelligence or the relationship between robots themselves – the so-called AIonAI law. This sixth law states: In Karl Schroeder's "Lockstep" (2014) a character reflects that robots "probably had multiple layers of programming to keep [them] from harming anybody. Not three laws, but twenty or thirty." In "The