Special relativity (alternative formulations)
Hendrik Lorentz and Henri Poincaré developed their version of special relativity in a series of papers from about 1900 to 1905. They used Maxwell's equations and the principle of relativity to deduce a theory that is mathematically equivalent to the theory later developed by Einstein.
Special relativity
The theory is "special" in that it only applies in the special case where the spacetime is flat, i.e., the curvature of spacetime, described by the energy-momentum tensor and causing gravity, is negligible. In order to include gravity, Einstein formulated general relativity in 1915. Special relativity, contrary to some outdated descriptions, is capable of handling accelerations as well as accelerated frames of reference.