### Special theory of relativity

The special theory of relativity describes that the maximum speed is the speed of light.

##### Explanation

Time is not a constant factor. As speed increases, time runs slower. The maximum speed is the speed of light, that we can never reach, as time would then stand still.

This theory explains the equivalence of mass and energy with the expression

The special theory of relativity is called "special" because it treats space without matter in inertial frames of reference. The general theory of relativity describes matter and the gravity that arises from it.

##### Additional Information

The German physicist Albert Einstein published the theory in 1905.