Speed of light a laser beam is swept quickly across a distant object, the spot of light can move faster than "c", although the initial movement of the spot is delayed because of the time it takes light to get to the distant object at the speed "c". However, the only physical entities that are moving are the laser and its emitted light, which travels at the speed "c" from the laser to the various positions of the spot. Similarly, a shadow projected onto a distant object can be made to move faster than "c", after a delay in time. In neither case
Speed of light which all massless particles and changes of the associated fields travel in vacuum (including electromagnetic radiation and gravitational waves). Such particles and waves travel at regardless of the motion of the source or the inertial reference frame of the observer. In the special and general theories of relativity, interrelates space and time, and also appears in the famous equation of mass–energy equivalence . The speed at which light propagates through transparent materials, such as glass or air, is less than ; similarly, the speed of electromagnetic waves in wire cables is slower than . The ratio between and the speed