Nothing but Relativity, Redux

TL;DR

This paper demonstrates that the core principles of relativity can be derived without assuming the constancy of the speed of light or using light-based thought experiments, suggesting a historical possibility of earlier derivation.

Contribution

It shows that spacetime transformations consistent with relativity can be derived without explicit assumptions about light speed or differentiability, challenging traditional derivation methods.

Findings

Relativity transformations can be derived without assuming light speed constancy.

Historical derivations of relativity could have been possible centuries ago.

The derivation does not require differentiability or continuity assumptions.

Abstract

Here we show how spacetime transformations consistent with the principle of relativity can be derived without an explicit assumption of the constancy of the speed of light, without gedanken experiments involving light rays, and without an assumption of differentiability, or even continuity, for the spacetime mapping. Hence, these historic results could have been derived centuries ago, even before the advent of calculus. This raises an interesting question: Could Galileo have derived Einsteinian relativity?