The theory of special relativity was proposed in 1905 by Albert Einstein in his article " On the Electrodynamics of Moving Bodies ". The title of the article refers to the fact that special relativity resolves an inconsistency between Maxwell's equations and classical mechanics. The theory is based on two postulates : (1) that the mathematical forms of the laws of physics are invariant in all inertial systems ; and (2) that the speed of light in a vacuum is constant and independent of the source or observer. Reconciling the two postulates requires a unification of space and time into the frame-dependent concept of spacetime.