It is certainly within the realm of rational scientific inquiry to ask, not simply what a clock measures, but it what manner it measures. These are contextual to an experimental science. 1) In common to all clocks, how do clocks measure time? 2) Are there any clocks (that one actually observes from time to time) that will maintain accuracy without correction from external energy? Certainly not a sundial. Like a quartz watch it needs external energy to maintain its periodicity--just on a much larger time scale. 3) Do all clocks in operation involve periodic repetition? 4) Can a clock be measured without effecting its accuracy? In a sub-forum devoted to relativity it is natural to recognise the unification of space and time, as well as inquire about their differences beyond a negative sign in the metric. 5) A yardstick in operation does not increase the entropy of it's environment (Or does it?). Are there any clocks for which this is true? 6) A yardstick in operation measures the distance between two space-time events where clocks at each end of the stick are synchronized, right? 7) As in 6), but when measuring with a clock, what are the yardsticks doing? After some of the wild speculations within a recently locked thread, it’s probably a good idea not to confuse, without justification, what a clock measures with how it measures.