A reference frame is a set of coordinate axes that help describe the position or movement of an object. There are two basic types of reference frames: inertial and accelerating. Inertial frames are those where the coordinate axes appear to follow Newton's first law in every direction from the point of view of an observer: things at rest tend to remain at rest unless acted upon by an external force. An accelerating frame, on the other hand, is one where the coordinate axis are accelerating from the point of view of an observer, such as a rotating merry go round or an accelerating rocket ship.

Two types of transformation are used when transforming or mapping coordinates from one inertial frame to another. If the constant velocity of the frame is zero or small compared to the speed of light, a Galilean transformation is appropriate. However, if...