[Lance_ET_Compte]

A thousand years ago, every village had their own timekeeping and it worked. Our village is now earth. What if we just abandoned daylight-savings time and timezones and just went with GMT (or anything else) for everywhere on earth?

There would be cultural effects as people in California now start work at 16:00, for example...

[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.

[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.

[bakkoting]

Here's a good essay about that: So You Want To Abolish Time Zones [1]

[1] https://qntm.org/abolish

[Lance_ET_Compte]

That's a really good essay. My mind has been changed! Thank you!

[troad]

'Global time' is a perennial HN comment on articles to do with time handling, and a truly terrible idea.

Try selling East Asia and Australia on the idea that they should wake up at 7pm, go to work on Friday, finish their workday on Saturday, and then go to bed at 11am -- for the benefit of people on the other side of the world who can't be bothered figuring out local time.[0]

Will it fix software issues around time handling? Why not, I'm sure things like having trading days on the Hang Seng stock exchange that run over overlapping two-day periods (the Nov 11-12 trading day, the Nov 12-13 trading day, ...) won't cause any unexpected issues at all. Quick, what's T+2 settlement for a trade on Nov 12?

And how would Europeans react when the global majority vote to move the suddenly-meaningful Prime Meridian to much more populous and economically important regions than London, and it's now Europe that gets to experience that kind of day, for the benefit of Tokyo and Beijing?

[0] Not to mention, 'global time' won't help with scheduling at all, since the question "what time is it there?" just gets replaced with "when do they work and sleep there?". 10am local time gives you actionable information about whether people in a given place will be awake or not, 10am 'global time' does not.

[hakfoo]

A few years ago, I bought a kit for a network-controlled self-synching clock, mostly as an excuse to practice SMD soldering. It came from a Chinese vendor, and China has only the single time zone, so the firmware was not designed with any sort of time-zone adjustment.

So I had an extremely accurate clock on my desk that was locked to Beijing time.

It was still viable, I just needed to note that it was time to get up for work when the clock said 02:00 instead of 07:00.

With regards to scheduling, we still have to negotiate when a meeting takes place-- "I may work nominally 09:00 to 17:00, but I have another appointment at 13:30", but it would eliminate the phase of trying to disambiguate "do you mean 13:30 your local time or mine?"

If you're using a shared calendar platform, specifying active hours is common anyway.

[poincaredisk]

>And how would Europeans react when the global majority vote to move the suddenly-meaningful Prime Meridian to much more populous and economically important regions than London, and it's now Europe that gets to experience that kind of day, for the benefit of Tokyo and Beijing?

I'm honestly fine with it. I already often go to sleep 5am my time and wake up 13:00 (my sleep schedule is not typical), so I'm not that far from your horror scenario. But anyway, what difference does it make it people wake up at 3:00, 14:00 or 22:00? This is just a random reference frame you got used to.

[cle]

The hard part is not doing it, it's getting people to agree. I highly doubt people will agree to do that, because a large portion of people don't agree with "our village is now Earth".

[tshaddox]

In order to do computing involving time zones you also need to get an enormous number of people (particularly vendors of computer operating systems and maintainers of programming languages) to agree. But yes, this does appear to be easier than getting a few hundred political jurisdictions to agree.

[throitallaway]

Our world has gotten smaller. For people that travel often and schedule calls across time zones, time zones are a complete pain in the ass. I've advocated for getting rid of time zones for ~10 years now. It really doesn't matter if people in California start work at 16:00; the people that live in that area will get used to it. Daylight will remain the same.

[maxwell]

UTC is problematic since it splits the day: when it's midnight in Greenwich, it's still yesterday for half the world. The Unix epoch occurred in 1969 in Hawaii.

BIT (UTC-12) is better. Only positive offsets. Everyone on the same day.

[schoen]

Don't you get the "it's already tomorrow for half the world" problem in place of the "it's still yesterday for half the world"?

[autarch]

Time zones _without_ DST would be relatively easy to deal with. The answer is not "abolish time zones", it's just "abolish DST".

[soperj]

I'd adjust to that better than adjusting to Daylight savings time.

[fermuch]

Isn't that how china works? One timezone for everyone

[ianburrell]

That is good example why one timezone doesn't work. The locals in Xinjiang use a local time zone +6, instead of China time +8, because the latter is too far off the daylight hours.

My understanding is that use of Xinjiang time has dropped recently because of the crack down on Uygurs and government forcing China time.

[a57721]

There are various countries that optimize the number of time zones for administrative purposes, but this is much easier and sensical to implement within one country than globally.

UTC is used globally when it makes sense, e.g. for the schedules of international radio broadcasts.

[chanandler_bong]

This. 100%.