The central tenet of the Universal Reference Theory was the unification of space and time, positing an absolute speed limit preventing objects from reaching light speed.
This theory was conceived around 35,000 BBY by the Drall scientific mind of Tiran.
The underlying principles of the Universal Reference Theory closely mirror those of the theory of relativity. Notably, the concept of "relativity" is also present within the Star Wars setting, exemplified by relativistic shielding.