[ianburrell]

Everyone would create local time zones and use them. It is convenient to have the clock synchronized to the local day. Using UTC optimizes for long distances when people use local clocks much more often.

How do you handle the date changing in the middle of the day? If I was on UTC, the date would change at 5pm. Is that still Wednesday or would it be Thursday?

Also, it doesn't solve the problem since still need to figure out local time when interacting long distances. If need to keep track of local times, might as well use time zones.

Finally, can solve most of the problems with time zones by including UTC time with anything long distance. Say "meeting is at 4pm, 23:00 UTC", then nobody has to worry about your local time zone.

[skissane]

> How do you handle the date changing in the middle of the day?

In the Jewish and Islamic calendars, the day begins/ends at sunset, and hence the date changes at that point.

Traditionally, (Western) astronomers used the astronomical day, going back to Ptolemy, in which a new day starts at noon. Part of the reason for this was that in pre-modern times it was a lot easier to precisely determine the moment of noon than the moment of midnight. Contemporary astronomy has mostly abandoned that tradition, but it still survives in the definition of Julian dates (but not Modified Julian dates which moved the day boundary to midnight)

[poincaredisk]

>It is convenient to have the clock synchronized to the local day

Is it really, or are we just used to it? This seems to be busy a random reference frame.

I, for example, am an extreme night owl, and often go to sleep at 5am or later. So, to me, 12:00 is very far from the middle of the day (in fact, sometimes I'm still asleep at that time). This desync doesn't cause any problems for me.

[Vampiero]

> This desync doesn't cause any problems for me.

Are you sure you're not chronically depressed? Because our brains and bodies have this thing called a circadian rhythm, which causes all sorts of problems when disrupted. Being a night owl is no excuse, and it's often just a symptom of some underlying issue

[tshaddox]

> How do you handle the date changing in the middle of the day?

It seems like you would have to do absolutely nothing? Just like you do absolutely nothing to "handle" the hour changing throughout the day. People work overnight shifts. People schedule important events close to and on either side of midnight.

[sethammons]

"did it happen wednesday the 23rd or wednesday the 24th?"

[tshaddox]

I wouldn't expect that confusion to be common. It's already common to say things like "I got terrible sleep on Wednesday night" even though some or all of the bad sleep might have happened after midnight and thus technically on Thursday.