Speed of light zero, "γ" is equal to one, giving rise to the famous formula for mass–energy equivalence. The "γ" factor approaches infinity as "v" approaches "c", and it would take an infinite amount of energy to accelerate an object with mass to the speed of light. The speed of light is the upper limit for the speeds of objects with positive rest mass, and individual photons cannot travel faster than the speed of light. This is experimentally established in many tests of relativistic energy and momentum. More generally, it is normally impossible for information or energy to travel faster than "c". One
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