A Brief Note on the Clock-Hypothesis

Abstract

The clock-hypothesis is the fundamental assumption in the theories of relativity that duration, measured by clocks, is proportionate to the length of their respective world lines. Over the years, there have been contributions both, theoretical and experimental in nature, either confirming or questioning this hypothesis. We give an elementary model of two classes of clocks, which turn out to be relativistic clocks, and by doing so also offer a basis to see the limitations of the clock-hypothesis. At the same time, we find support for a hypothesis of L. de Broglie, regarding the existence of an internal clock of electrons. Our aim is to give a precise, yet accessible account of the subject.