Formulations of special relativity

The theory of special relativity was initially developed in 1905 by Albert Einstein. Moving beyond the traditional formulation, newer interpretations of special relativity have been developed on the basis of different foundational axioms. While some are mathematically equivalent to Einstein's theory, others aim to revise or extend it.

Einstein's formulation was based on two postulates, as detailed below. Some formulations modify these postulates or attempt to derive the second postulate by deduction. Others differ in their approach to the geometry of spacetime and the linear transformations between frames of reference.