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 (alternative formulations)
Hsu & Hsu then explore other relationships between w and t such as w=bt where b is a function. They show that there are versions of relativity which are consistent with experiment but have a definition of time where the "speed" of light is not constant. They develop one such version called "common relativity" which is more convenient for performing calculations for "relativistic many body problems" than using special relativity.