Right. It's like when countries switched to the Euro or decimalized. There's a period when everything feels really janky and everyone complains and then a couple of years later everything is just fine and they forget what the old system was even like.

I know a lot of people who still think in the old currencies. Similar phenomena happen for people in countries that redenominated their currency, like Romania, where people still use the old amounts in spoken language.

Not switching to metric for time is reasonable, because there are already two existing 'natural' units for time (the day and the year), and they don't align on each other in metric (a year of exactly 1000 days would be so much easier, but we'll have to deal with reality as it is... or accelerate the rotation speed of the planet I suppose).

So long as we live on earth, metric time won't make much sense.

A year and a day don't line up at all, so we get weird leap days.

Is there any reason they should? Unless the Earth were tidally locked to the Sun, I'm not aware of any reason a day would have any relationship to a year.

It would be convenient to not having to deal with leap days and other such constructs. Of course, we cannot choose how these things behave, and therefore using a calendar not aligned to the natural cycles of our planet would be even less convenient, and would only start making sense when humanity develops into an interplanetary civilization.

The US isn't on a 365.24-based system, either. Days don't fit neatly into years, anyway.

That would have no impact on decimalizing sub-day units: 10 decidays in a day, 2 millidays to cook an egg... But no country did it, which speaks to the power our time traditions really hold in our psyche.

>That would have no impact on decimalizing sub-day units:

part of it is natural. We roughly divide day and night into 2 parts, so we already need to have considerations for halves.

It seems like base 12 was chosen simply due to religion. the zodiac defined the hours at night for ancient egypt, and the Goddesses of Seasons for Greece later on.

Minutes and seconds came because we let astronomers define them based on hours and movements of the sun along a dial. The time it'd take for a dial to traverse a literal arcminute and arcsecond (which is still a thing today). Though these times are very different from today's minutes and seconds. So we have math to thank for the base 60 measurements.

> part of it is natural. We roughly divide day and night into 2 parts, so we already need to have considerations for halves.

I forget which country did it but their historical time system counts hours as two halves from sunrise and then from sunset... That sounds a lot better than noon and midnight, to me. We could totally do

  sunrise = 0.00
  sunset = 9.99 -> 10.00
  sunrise = 19.99 -> 0.00

(For some standardized values of "sunrise" and "sunset" that don't slide around over the span of a year.)

The French did try to switch time to decimal after the Revolution. It was probably the most hated change they made by the local population, and didn't last long.

The problem was that it messed with the week, having a "day of worship / rest" every 7 days, which was then every 10 days