You could call this lots of things, but you shouldn’t call it “metric” because its second is not a metric second. In the SI (metric) system, the second is one of the fundamental units. The world does not need a conflicting definition for the second.
As someone who’s implemented a date and time library, the real pain is in dates, leap seconds and time zone transitions. 86,400 seconds in a day is a relative piece of cake.
The AM/PM thing is a solved problem. Many countries (not the one I live in) already use a 24 hour clock, in which 11pm is 23:00. Because many countries use it, most devices that keep time can be set to 12 or 24 hour clock. That includes almost every clock I own, including the oven in the kitchen, my car, all the HVAC units, and of course phones and computers. An exception is the irrigation system – the old one (designed in the USA) supports 24 hour time, but its replacement (designed in Australia) does not. I don’t think anyone, seeing all my clocks, has ever commented on them being in 24 hour mode. Most people have seen it before.
You are right of course but also keep in mind that, and that is just my thoughts after reading, is that the French tried to implement decimal time along with the rest of what we call the metric system in the 18th century. And it was the only system people rejected. So I think the author named everything metric to make the point that if it would be part of the system a metric second would be … long. But again I could be wrong. In any case the page would also work by naming everything decimal-something. Maybe not as catchy.
I don’t know the exact history, but the rest of the metric system is designed with a base unit and decimal derivatives. Assuming we want to keep the day length consistent (I can’t imagine a system being practically useful otherwise), we’d have decidays, centidays, etc. and not have hours, minutes, and seconds in the system at all. A system with days, decidays (2.4 hours), millidays (1.44 minutes), and microdays (0.0864 seconds) doesn’t seem bad to me at all, I’m sure people would come up with a good name for 10 microdays for daily use (0.864 seconds).
kDay, MDay, etc could work in space but they don't fit well with the length of the year. As long as we live on Earth we cannot escape from our planet taking about 365 days to orbit the Sun. History proved that it's convenient to have the same event (let's say start of spring) falling at the same date every year. Hence all the refactoring of calendars and leap years.
I wonder how we would settle that matter if we'll ever be able to travel fast between planets. Each city had its own time zone before trains required us to sync them because of conflicting railroad timetables. So we ended up with the current timezones. With planets, each one would have its day length and number of days in the year, maybe even inconstant seasons in the case of precession of perihelion or double star systems. I'd say we'd settle on local time and a common space time but who knows.
I never thought about this. And actually never bothered to read up on the proposed terminology. Only thing I always assumed was that the first draft of all terms is not 100% what we use today. Especially because it comes from France. But that’s only assumptions. But yes I think you are right with the naming convention.
Time was the same for the people that were measuring it with the same tools.
Western sundials started with 12 hours as they worked only during the day [1] and people that were not measuring time eventually measured it with a 24 hours system.
I could not find many sources about Chinese sundials but from the pictures at [2] you can see that they had 12 hours in all the day. A hour on the second sundial is divided in 8 parts. The one in the first picture seems to have the same 8 characters as the other one but each hour is divided into 2 parts, each divided in 4 parts.
I'm not surprised that everybody settled around some small and convenient number. 12 has more factors than 10 and dividing by 2 is more convenient than dividing by 3. I would be surprised to find a 9 or a 15.
There is no conflicting definition. Minutes, seconds, thirds, and fourths etc. are sexagesimal subdivisions, as tenths, hundreds, thousandths, ten thiusandths etc. are for decimal.
I know what you mean, and you are correct in that this is why we have minutes and seconds of arc, but the linked page is literally suggesting a different definition.
there is no multiple definitions going on: what happened is an _elision_.
The actual word is "second minute" (as opposed to the "first minute").
Most languages have by now elided "first" from "first minute" resulting in the "minute" as we know it today, and elided "minute" from "second minute" resulting in the "second" as we know it today.
i.e. "second" literally means "the one that comes after the first", but is implied to be about the subdivision of the small unit of time.
Part of the point is the "second" definition based on a subdivision is no longer the SI second. You are right about the elision, but in the context of the time most people are now eliding System International ("SI") from the beginning rather than "minute" at the end.
"Seconds were once derived by dividing astronomical events into smaller parts, with the International System of Units (SI) at one time defining the second as a fraction of the mean solar day and later relating it to the tropical year. This changed in 1967, when the second was redefined as the duration of 9,192,631,770 energy transitions of the cesium atom."
A while "prime minute" generally contains "61" "second minutes" it sometimes can contain 61 "second minutes"; so clearly the "second minute" is the true unit here :-)
As someone who’s implemented a date and time library, the real pain is in dates, leap seconds and time zone transitions. 86,400 seconds in a day is a relative piece of cake.
The AM/PM thing is a solved problem. Many countries (not the one I live in) already use a 24 hour clock, in which 11pm is 23:00. Because many countries use it, most devices that keep time can be set to 12 or 24 hour clock. That includes almost every clock I own, including the oven in the kitchen, my car, all the HVAC units, and of course phones and computers. An exception is the irrigation system – the old one (designed in the USA) supports 24 hour time, but its replacement (designed in Australia) does not. I don’t think anyone, seeing all my clocks, has ever commented on them being in 24 hour mode. Most people have seen it before.