UTC Is Enough for Everyone, Right?

How does that fail? I have an integer for an appointment. I am at that appointment at that given integer. This applies for all timezones. If the timezone changes, the integer does not. What you are saying is that the timezone changes and the integer changes aswell, but then it's not the same appointment anymore.

From the user's perspective it is the same appointment. They think they have an appointment at 3:00 PM on Thursday. If there's a timezone change, and you just stored an integer, then from the user's perspective the meeting changed from 3:00 PM to 2:00 PM.

Of course, if you have a meeting that spans timezones, this is unavoidable. I think the real solution actually lies in how the meeting time is expressed to the user so they don't have misconceptions about it.

> If you're like me and immediately said ohhhhhhhhhhhh, so THAT'S why there's twelve hours in a day! and immediately followed it up with: wait, why the fuck are they using twelve instead of ten? ...

> It's most likely because you have twelve joints in your hands: three in each of the four fingers, excluding the thumb. I thought that was pretty nifty to discover. Like, I had never looked at my hands before, really. Hands are really wild, when you think about it.

Probably not. This explanation of duodecimal is really farfetched and I’m pretty sure it arose from someone staring at their hands desperately trying to come up with a way to count 12 on their fingers to explain this. (Ten fingers and two feet seems as likely.)

Clocks are (probably) divided into (two sets of) 12 hours for the same reason feet are divided into 12 inches. Because it’s convenient for everyday use. Subdivisions of 1/12th suck for complex math (if your number system is decimal anyway), but are great for lay use. 12 subunits captures halves, thirds, and quarters, all of which are very intuitive and very common in everyday use.

12ths are handy enough that we have a special word for “12 of something” (dozen) even though our numbering system is decimal.

> 12ths are handy enough that we have a special word for “12 of something” (dozen) even though our numbering system is decimal.

My understanding is that the etymology of dozen is originally traced back to duodecim (Latin for twelve) via French dozeine. Which is interesting, but doesn't really explain why it's special beyond your observation that it's a highly composite, but comfortably small, number.

When we were building a golf tee time web site we eventually decided on this as well: always store the date-time as a string in the timezone local to the event. Convert to a date-time object in whatever timezone the user prefers (or golf tee time service APIs prefer :-P) on demand.

There is still a caveat, though. Locations can change timezone. Sometimes they do it fairly often (like every few years). You need access to a good timezone/location database that is updated regularly :-(

When we were doing this project, I was really surprised at how often we got problems. If you sell things all over the world (there are golf courses in ridiculous places), the probability that you will stumble into an anomaly is surprisingly high. Alas, this project was not a commercial success as the margins on tee times are quite small (and the tee time services you have to work with are often quite badly written). But it was quite fun to work on.