Which is why I said define arbitrary earlier. I believe it had to do with accuracy of measurement equipment in the 1950’s as well as the ephemeral time scale, which was based on the observed movements of astronomical entities. So you can kinda argue either way. The selection of units can be influenced by an older system like you said, but that still is a system that was based on an observable or measurable phenomenon, which doesn’t fit the definition of arbitrary.

Maybe those planets/stars in the cartoon were aware of their own non-linear travel, as well as red/blue-shift effects, and that we earthlings based our original systems of measurement on them without prior knowledge of those factors, thus making them inconsistent and arguably arbitrary haha

I believe that was because at the time of its discovery, that was the most accurately we could measure it. It’s still based on a stable, constant, absolutely measurable phenomenon though. You can divide it into whatever arbitrary or non-arbitrary units you want, but that system of measurement is still based on an absolute standard.

It’s like saying that we now define one year as 1.234 earth revolutions around the sun. Or 2. Or whatever. Arbitrary units perhaps, but still based on an absolute phenomenon.

If you really want to throw a wrench into this whole concept though, mention that the earth’s rotation is slowing ever so slightly over time… so we have to add time on to the atomic clock to attempt to sync it better with the earth’s non-linear rotational velocity. Who’s arbitrary now?! 😀

If there were reasons that it was divided that way, as you said, then that would make it non-arbitrary, as it was based on a system of logic. Define arbitrary, I guess.

Perhaps it would appear to be arbitrary though to those who aren’t aware of those reasons/logic, like the astronomical objects in the cartoon 🤷‍♂️😀

The measurement of earth orbiting for one revolution around the sun (a unit of time we refer to as a year) isn’t arbitrary. It’s clearly defined. You’ve either made one complete revolution or not. It’s just that the original starting point for the first measurement was arbitrary because you’d have to start somewhere.

Many forms of measurement are based on absolutes, like temperature, measured from absolute zero, or time, measured against the cesium standard (atomic clock). You’d have to break physics in order to be able to define them as arbitrary.

It’s to allow one for each day of the week except for Sunday, as Sunday is The Lord’s Day.