Light – The Absolute Measuring Tool

This article analyzes the relationship between two Cartesian coordinate systems, each linked to an inertial reference frame (IRF), when these are in relative motion. Building on the L-ARF framework, it is assumed that communication between the systems occurs via light signals traveling at constant speed c, while the systems move relative to each other at constant speed v. Through a thought experiment in which a light signal is sent from a system F to another system F', the times t and t' of the signal's arrival are derived, expressed in each system's variables. The result shows that t = t', i.e. no time dilation occurs. Furthermore, through a thought experiment with reflected light signals against two points in F, it is shown how F' can determine the length of a rod in F based solely on the time difference between the signals' return — without the length contraction predicted by special relativity.