Australia/Lord_Howe is the weirdest timezone • Hacker News Board

Re: Australia/Lord_Howe is the weirdest timezone

#391

Post by 1-more » Wed, Oct 30, 2024, 11:12 PM UTC

foobarchu wrote: post #349

apelapan wrote: post #132

Earlier quoted context omitted.

There used to be at least one airport in a tribal area in the US, that had the timezone of the reservation (not same as state) but the DST of the surrounding state (not same as reservation). Can't remember the code for it now, had a lot of interesting timezone issues in a previous job.

My favorite is the hopi reservation, which does not observe DST and exists entirely inside of the Navajo reservation, which does observe it, and which exists entirely within Arizona, which again does not observe DST, and exists entirely within the United States which does observe DST in the general case.

I'm guessing that the airport was this one maybe? ttps://en.wikipedia.org/wiki/Window_Rock_Airport

Also IIRC (cum grano salis) the federal buildings in the Hopi reservation do observe DST and the state buildings in the Navajo reservation don't. But don't quote me on any of those actually existing.

A fun fact circa 2012 was I was writing a PHP server that needed to talk to a Windows server to schedule things. Windows server used Microsoft's own timezone system, not IANA or anything like that. I went looking for an implementation of IANA MS conversion. I ended up finding all these forum posts by Windows Phone (RIP) users in Arizona who had the wrong time on their phones. So it was nice to know that 1) there was no fixing it and 2) they eat their own dogfood.

Re: Australia/Lord_Howe is the weirdest timezone

#392

Post by SllX » Wed, Oct 30, 2024, 11:17 PM UTC

layer8 wrote: post #340

yyyfb wrote: post #333

Earlier quoted context omitted.

If the continental US can do it (and it looks like it might soon, with California voting for it) I'm not sure I buy that argument. Heck if China can survive on one timezone...

They certainly could if they had started that way, but changing it now will disadvantage at least one of the countries (Spain for example), and those countries’ politicians don’t want to risk the ire of their voters for the greater good. And DST is regulated on the EU level, so can’t be changed by individual EU members without breaking EU law, like apparently individual US states can. It’s status quo bias and loss av…

> like apparently individual US states can.

Nah, the States can’t. What we actually voted for, and I voted for this too, was that if Congress passed a law that enabled States to move to permanent DST, then the legislature is authorized to pass a law to move California to permanent DST. Congress hasn’t acted, and the main guy who was pushing for this isn’t in the legislature anymore, but basically the law did nothing except send a message from Californians saying “yeah, this sounds good, do it.” but technically it was never necessary.

Re: Australia/Lord_Howe is the weirdest timezone

#393

Post by derefr » Wed, Oct 30, 2024, 11:18 PM UTC

kccqzy wrote: post #286

The most amusing tidbit about the tz database is that it contains an estimate of Big Bang, and it refuses to calculate timezone transitions occurring before the Big Bang. The commit message at https://github.com/eggert/tz/commit/b22d459a367f4d01b10f6f6b... says: > For example, Glib computes Sao Paulo time stamps as if Brazil's circa-1913 rules were still in effect. (Thanks to Leonardo Chiquitto for reporting the bug.…

Honestly, that seems quite practical — it's a good way to head off "angels dancing on the head of a pin"-style arguments between contributors.

Another way to put the bug outcome is: "Instants before the Big Bang are out of scope of this library, so if an algorithm produces incorrect values, but only before the Big Bang, the algorithm is acceptable and does not need to be improved/replaced."

Re: Australia/Lord_Howe is the weirdest timezone

#394

Post by derefr » Wed, Oct 30, 2024, 11:19 PM UTC

ucarion wrote: post #313

kccqzy wrote: post #286

The most amusing tidbit about the tz database is that it contains an estimate of Big Bang, and it refuses to calculate timezone transitions occurring before the Big Bang. The commit message at https://github.com/eggert/tz/commit/b22d459a367f4d01b10f6f6b... says: > For example, Glib computes Sao Paulo time stamps as if Brazil's circa-1913 rules were still in effect. (Thanks to Leonardo Chiquitto for reporting the bug.…

This is really neat! Separately, I'm a little skeptical of the tzdb's endeavor of even thinking about pre-Unix-epoch stuff. The bug-to-utility ratio of that stuff doesn't seem to be there. `zic` is where most of the ugly gnarliness of tzdb lies, and I sometimes feel that it would have been better if `zic` weren't an artifact others could depend on.

There are plenty of people alive today with negative birth timestamps, with many services wanting to calculate the proper local day and time each year to send them annoying pseudo-personalized birthday messages.

Or, for something a bit more agreeable: genealogy (esp. the bioinformatics queries in genetic genealogy) needs a good, high-resolution timeline to normalize events onto. Actually, the non-genetic kind of geneaology, solves a lot of vagueries in lineage as constraint-based puzzles over (local!) dates, with razor-thin margins that would be messed up without correct timezone-based calendar conversion — constraints like "two people couldn't have been related as mother and child, if the mother died at least two days before the child was born."

Re: Australia/Lord_Howe is the weirdest timezone

#395

Post by krick » Wed, Oct 30, 2024, 11:27 PM UTC

The most interesting (perhaps, the only truly interesting) thing in this writeup is his `tzdump` script. I checked his github, and it seems he didn't share it anywhere, unfortunately.

Re: Australia/Lord_Howe is the weirdest timezone

#396

Post by [deleted] » Thu, Oct 31, 2024, 1:06 AM UTC

apelapan wrote: post #132

hocuspocus wrote: post #91

Earlier quoted context omitted.

> The naive way to do so would be via a static mapping of state to time zone but there are a few edge cases that preclude doing this More than a few, state is really the wrong resolution here, US timezones follow counties and native reservations borders. ZIP codes should probably be good enough but I'd be careful too. If your volume of addresses isn't too crazy, the robust way is to reverse geocode them and use a lib…

There used to be at least one airport in a tribal area in the US, that had the timezone of the reservation (not same as state) but the DST of the surrounding state (not same as reservation). Can't remember the code for it now, had a lot of interesting timezone issues in a previous job.

[deleted]

Re: Australia/Lord_Howe is the weirdest timezone

#397

Post by blahedo » Thu, Oct 31, 2024, 1:54 AM UTC

radekk wrote: post #16

I wonder why the dst transition hours are encoded in local time. Wouldn't it be easier to do it in UTC? There is no need to differentiate between the same hour before and after change then.

I bet it's North America bias—we roll our time changes across the continent one TZ at a time, at 2am local time (which also explains why the default is "/2").

Re: Australia/Lord_Howe is the weirdest timezone

#398

Post by troad » Thu, Oct 31, 2024, 1:55 AM UTC

Lance_ET_Compte wrote: post #273

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...

'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.

Re: Australia/Lord_Howe is the weirdest timezone

#399

Post by nine_k » Thu, Oct 31, 2024, 2:10 AM UTC

nerdponx wrote: post #249

nine_k wrote: post #202

Earlier quoted context omitted.

This is indeed a more logical clock, as it follows the natural cycle of activity. Equally, calendars that put the end of the year at the time after harvest ("autumn"), or at the start of agricultural work ("spring") are also more logical. Positioning the beginning of a new day at noon, and a new year t a solstice, is just a technical convenience, because these are easy to detect with very simple astronomy tools.

What makes it more logical? The wheel turns all the same no matter where you mark the beginning. In the Northern hemisphere, there's actually something nice about starting the year in the dead of winter: it feels like the year is born in the spring and then dies away the following winter, not unlike a lifetime.

The whole lives of the societies which have actually invented these calendars were built around the vegetation cycle, which ruled pastures, fields, and orchards. So the yearly cycles of food availability, work, seasonal migrations, and the correlated weather pattern changes were all reasonably aligned with the start / end of the year.

Peoples as diverse as Celts, Romans, Slavs, Babylonians, Hindus, and various peoples in China all used a variety of a calendar where the yearly changes were aligned around modern October-November and modern March-April.

A calendar with the year starting in January and with astronomically (more) precise years was promulgated by Julius Caesar in -46. (I suspect the introduction of the concepts of Babylonian astrology to Rome a century before may have played a role in the desire to align the calendar to stars and not to earthly affairs.)

Re: Australia/Lord_Howe is the weirdest timezone

#400

Post by jmbwell » Thu, Oct 31, 2024, 2:30 AM UTC

zokier wrote: post #387

jmbwell wrote: post #282

Those interested in this kind of pedantry might also take care to note that it’s called “daylight saving time,” with no “s.” It is a system of time for saving daylight. It is not a sales event promising “savings.” Frustrating to read an otherwise excellent and detailed article that makes this error throughout.

Both forms are widely used and accepted. Wikipedia has whole section about that: https://en.wikipedia.org/wiki/Daylight_saving_time#Terminolo...

Thanks at least for citing a reference and not just saying “language evolves” or something.