Fermi–Walker transport

Summary

Fermi–Walker transport is a way to carry vectors along a timelike curve in spacetime. It keeps the tangent vector of the curve fixed and rotates other vectors as little as possible. It extends parallel transport from geodesics to accelerated world lines; along a geodesic the two agree. A Fermi–Walker transported orthonormal frame is the natural non-rotating frame of an accelerated observer. It models the axes of gyroscopes on which no torque acts. It is used to build Fermi normal coordinates and to describe Thomas precession.