BTW. A long, informative post without a single mention of AI. A rare thing these days.
Snake Emoji Kanye vibes are the weirdest timezone.
Then the second half is often to reverse your "I think it will happen X seconds from now" delta-guess into "I'm also guessing that your timezone's clocks will say Y when it happens."
Just don't forget to keep track of which timezones is controlling the event versus which timezones it is being displayed in. ____
[1] Your UTC estimate might occur plus or minus leap seconds. TAI is safer, unless somebody discovers something exciting and new that changes the behavior of cesium atoms.
[0] Such as if the time zone vanishes because the country is gone. Or perhaps the 1:30 to 2:00 thing couldn't exactly happen because the clocks went forward from 1:00 to 2:00 with a missing hour.
It is not because most of the world do summer time and that when they do they have a 1h transitions that we should take it for granted.
This article do not mention the Chatham Standard Time Zone from Chatham Islands archipelago in NZ which is 45 minutes ahead of New Zealand Daylight Time, nor the Central Western Standard Time (Australia/Eucla). Also wikipedia mention there is a "train timezone" for the Indian Pacific train. I wonder if other trains have a dedicated timezone?
They used to, railway time is how our timezone system came to be.
Eh? Most of the world don't do summer time.
> Hmm. 410 timezones just don’t DST at all. 185 have a 3600-second, i.e. 1-hour, difference.
My point stands that there is no normality, just governments taking different decisions and being entitled to it and what the majority does is not relevant.
I think the statement is true by any reasonable metric - population, land area, GDP size.
The only search hits I found for this claim are your comment. I find no such mention at https://en.wikipedia.org/wiki/Indian_Pacific . What are you referring to?
Without any additional update to the tz database, all annual transitions are assumed to continue indefinitely. So TZif version 1 would repeat transitions up to January 2038 (i.e. the end of signed 32-bit time_t), while version 2 or later would keep them for the compatibility (see the section 4 of RFC 8536) but also include the algorithmic description in the footer for later dates.
(Or did you ask something else entirely? It wouldn't be the first time I misunderstood things about time zones.)
Instead the locals offset the time by 6 hours. So the AM cycle starts at dawn (i.e. 6am), and the PM cycle starts at dusk (i.e. 6pm).
I object to the latter since software is not the source of truth, the social practices it aims to encode are. It is perfectly reasonable to say that this particular practice is so rare that it is out of scope, but this makes tzdb a not quite correct approximation of reality, rather than reality an approximation of tzdb.
There are people who want to end any other human to ever live homeless in starvation or any kind of poverty and there are people who want to eliminate anyone they judge as threat or a nuisance while reinforcing there feeling that they dominate everything that will ever matter in the world and the rest.
Software can help all kind of purpose.
Let me define "local snoozing time" (LST): it's set to my local standard timezone as of today, but every time I hit the snooze button on my morning alarm it shifts 9 minutes backwards (the length of the snooze). By definition, I wake up at 8am in LST, regardless of what the world is doing.
If the time shifts by more than one hour compared to the prevailing timezone, LST shifts forwards by a whole number of hours on Saturday morning, 2am LST to minimize that difference.
This timezone is "boring" but uncomputable, since it depends on unpredictable events.
That must have been fun for the Romans here in Scotland - an hour would be roughly two and a half time as long in winter as in summer!
Mechanical clocks in Japan were designed to handle those situations:
> Adapting the European clock designs to the needs of Japanese traditional timekeeping presented a challenge to Japanese clockmakers. Japanese traditional timekeeping practices required the use of unequal time units: six daytime units from local sunrise to local sunset, and six night-time units from sunset to sunrise.
* https://en.wikipedia.org/wiki/Japanese_clock#Temporal_hours
Look where the sun is, remember where it is at sunrise/-set (much easier if you're outside every day) and then mentally divide the sky into segments and just ballpark it.
Well, maybe that was another problem with Scotland... ;-)
No wonder they built a few walls and retreated south....
Ethiopia is one of the ancient Christian countries, the second of officially convert and the Ethiopian Ortodox Church still seems prominent. I assume that's the reason why.
https://en.wikipedia.org/wiki/Ethiopian_calendar
The Ethiopian calendar has twelve months, all thirty days long, and five or six epagomenal days, which form a thirteenth month.
I like that Tolkien’s legendarium got the first mention here though.
Sometimes priests moved these days to suit political shenanigans.
Caesar ended this madness and "rationalised" the system, coincidentally making his year-long consulship last for 446 days.
The west inherits from the Romans, and Julius Caesar standardized away the Roman intercalary month by glomming it into Feburary. Before that a "priest" (the pontifex maximus) (in scare-quotes because it was a political office) would add that month on an ad-hoc basis. Not so different!
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.
Then shouldn't the start of the year be when the year is "born"? Or alternatively, the end of the year when the year "dies"? January 1 is neither.
It slowly grows after that and blooms later.
Which is exactly what we did.
I don't think anyone actually believes Jesus was born on Dec 25.
Now whether you yourself believe he was born then, another time or ever existed at all etc is another story.
I believe for example that everyone can believe whatever they want about those things as long as:
They leave me alone when I tell them I don't believe that and I don't want to be convinced
They don't try to kill me, enslave me, etc for being an infidel (yes that includes the Christian holy wars sort of thing but also current events)Children and people who have only a superficial knowledge of Christianity might very well believe otherwise. But they are poorly-informed.
Arguments against include:
a) Calendar dates are generally fuzzy from that period, particularly for events that are not formally documented. So the likelihood of anyone ever having known the correct date is very low.
b) The mythology around the birth does not match the seasonal expectations for late December (more likely springtime).
c) Dec 25 was chosen in 336 AD, by church decree. Prior to that, there was no holiday nor even a strong claim of any specific date.
d) Dec 25 was already a festival day for pagan celebrations of Saturn (Rome) and Mithra (Persia), which was likely a factor in the choice of date, to coincide with existing customs.
There are no substantial arguments in favor of December 25 being the accurate birth date of Jesus.
I don't think anyone actually believes ...
When this is pointed out, he explains why it can't be Dec 25th and that's all totally fine and correct but doesn't change the fact that yes indeed there are people that believe that, as well as lots of other things that can easily be disproved. It does not matter whether you can disprove it to us and others. These people that do believe it are in fact out there.
25 of December is close to the winter solstice (around 22nd), and I suspect it was ascribed to that day for astrological reasons; there are a few other astrological clues around that episode, most prominently, the Bethlehem Star.
Mar 31 - Aug 31 - Jan 31
Apr 30 - Sep 30 - Feb 28/29
May 31 - Oct 31
Jun 30 - Nov 30
Jul 31 - Dec 31
That highlights a few interesting cycles you can use to calculate dates from a simple count of days from the start of the year:
153 days every 5 months
61 days every 2
31 days per month
An "early reset" occurs every second month, jumping to the next 2-month cycle after the second day 30. Another occurs after every fifth month, jumping into a new 2-month cycle halfway through the last one of the 5-month. And of course, end of the year breaks the third "5-month" cycle WAY early, just before even its first 2-month is finished.
I won't try to detail the process of generating dates from this here, but I'm sure most of us here can work it out with just a little effort. Instead, here's a couple more fun facts to consider:
If you DO start the calendar from March, counting it as month 1, September (7) through December (10) map rather nicely to their own numeric positions. That seems a pretty strong hint, to me.
And I REALLY love this one:
The Gregorian cycle consists of four centuries. The first three are 36,524 days each: 100 years x 365 days + 24 days for the leap years. The hundredth year (ending in 00) is NOT considered a leap year, EXCEPT for every FOURTH hundredth. So that's 4 centuries * 36,524 days = 146,096, plus 1 more for the leap century, for 146,097.
That number is EXACTLY divisible by 7, which means the week cycle repeats WITH the Gregorian one. Good thing! Otherwise, we'd have to wait 2800 years!
- months are counted as 3, 4, 5, ..., 14, with 13 and 14 being January and February of the following year
- the contribution of the month to the day of the week is floor(2.6 * (m+1)) - the 2.6 comes from the 13 "extra" days (over the approximation 1 month = 4 weeks) in every 5 months.
That's why there frequent confusion about George Washington's birthday, along with other historical dates of that era: The New Year started in March when he was born, but changed to January during his lifetime (The British Empire switched in 1752). So being born in February, there's an ambiguity about the year, unless you specify which calendar you mean:
"George Washington was born on February 22, 1732, according to the Gregorian calendar. However, when he was born, the Julian calendar was in use, which would have placed his birth on February 11, 1731."
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.)
And before that they they started years from 1st of March, which is much closer to one of the Equinoxes, which is what all sane people (including french revolutionaries) consider to be the proper start of a year.
I live far from the equator - "Dawn" is sometimes after breakfast, and "Dusk" can happen before I get off work.
Then you get above the Arctic Circle, and there are days with neither. :D
The beauty of the "English clock", which isn't English at all, is that it simply defines a way to refer to the same point in time with a number (never mind that Daylight savings" nonsense) and you can refer to it whether you are a farmer, a software developer, a waiter, you live Africa or the arctic circle all the same.
If you live on the 45th parallel like I do, it isn’t logical at all since the length of a day is constantly shifting.
7 AM is 1 Saac ( Hour 1)
6 PM is 12 Saac ( Hour 12)
7 PM is 1 Saac
6 AM is 12 Saac
> 7 PM is 1 Saac
How do you distinguish AM/PM? How does one say that something will happen 19:00 specifically, and not 07:00?
https://digitalcommons.macalester.edu/cgi/viewcontent.cgi?ar...
In a place with considerable skew in daylight hours between the summer and the winter, this would be quite unintuitive, because daylight hours would become longer (and night hours shorter) during winter and spring, and the opposite for summer and autumn.
Either that, or a fixed conventional notion of "dawn" which only corresponds to the sun rising around the Equinoxes. Either way would be unintuitive.
This would also give a nice 3-part division to the day that matches their use: 1st 8 hours for the morning, next 8 hours for the afternoon, and the next 8 hours for evening/night. Currently, morning alone is 12 hours, and afternoon is like 6 (or less) and the evening takes the rest.
But I guess the current noon time is chosen for when the sun is highest in the sky, so maybe to preserve noon as the transition point, morning should start from 4:00 hrs, then the afternoon starts from 12:00 hours, and evening would start from 20:00 hours.
FWIW, the English-speaking world used to switch years on March 25: https://en.wikipedia.org/wiki/Calendar_(New_Style)_Act_1750#...
Neither of these are technically things that tzdb can even talk about. They're concerned with civil time, not calendars or other "reckoning" problems.
But I do agree with leap seconds: it's absolute trivia, not a useful thing for a programmer to know. Your computer smears them and you don't even know when they happened. You could completely forget them. Except that countries transitioned from ignoring leap seconds to considering them, so the switch in Australia from "GMT+x" to "UTC+x" a couple of decades ago was the transition from ignoring leap seconds to incorporating them. The fact that this is almost universally ignored is probably for the better.
By and large, I agree with this.
But I've always found it a bit funny when a large organisation [1] says "our servers have sub-millisecond timing accuracy, thanks to GPS synchronization and these PCIe rubidium atomic clock cards we've developed" while at the same time saying [2] "we smear leapseconds over the course of a day, in practice it doesn't matter if a server's time is off by ±0.5 seconds"
[1] https://engineering.fb.com/2021/08/11/open-source/time-appli... [2] https://engineering.fb.com/2020/03/18/production-engineering...
The relation between that time and what the rest of the world thinks the time is is actually less relevant.
The date of Ramadan is not well known because it's based on being able to see the moon from the local position on Earth. If the sky is particularly overcast for instance, then you cannot see the moon, regardless of where the moon is.
This presents problems for implementation of the calendar into the workings of a nation state. Many countries that adopt the Islamic calendar officially use an approximation, a pre-calculated date based on the moon's predicted visibility at a particular position.
The Islamic calendar is therefore not really one calendar, but two: the observational Islamic calendar and the predicted calendar, and both have a dependence on a location from which either real observations are made, or predicted observations are made.
I don't know how Morocco or Gaza do it.
Note to self, look up what Islamic scholars think should be done about Ramadan on a moon base.
> the Malaysian government called a gathering of 150 Islamic legal scholars, scientists, and astronauts to create guidelines for Dr. Shukor. The scholars produced a fatwa, or non-binding Islamic legal opinion, intended to help future Muslim astronauts, which they translated into both Arabic and English. They wrote that in order to pray, Muslims in space should face Mecca if possible; but if not, they could face the Earth generally, or just face “wherever.” To decide when to pray and fast during Ramadan, the scholars wrote, Muslims should follow the time zone of the place they left on Earth, which in Dr. Shukor’s case was Kazakhstan. To prostrate during prayer in zero gravity, the scholars stated that the astronaut could make appropriate motions with their head, or simply imagine the common earthly motions.
I’m not an Islamic scholar (or a Muslim at all), so this is just speculation, but my guess is that if it were a permanent settlement, with people being born and living their whole lives on the moon base (so “where they left earth from” is not meaningful), they’d probably just settle on one permanent Earth time zone to follow; presumably either that of Mecca, or that of whatever country on Earth (if any) owns the base.
Maybe, all I know is that it was relevant for me during the first years in industry. If you work with timeseries which comes from source systems you don't 100% controll, like in many industrial settings, its important to know about them, and how they are handled upstream. Do the source do smearing, or does it just sync every X hours? Does it sync with NTP, which will smear (slew) the change, or have they implemented their own thing? Do they just run `ntpd -q` regularly?
But yeah, as I type it out I realize that most programmers probably don't work in that domain:-p
Even in applications where we don't particularly care, there have been a surprisingly large number of leap second-related bugs. CGPM have decided to abolish the leap second for good reason.
https://en.wikipedia.org/wiki/Leap_second#Other_reported_sof...
Especially when, even disregarding the ones with special rules, there's a couple that are 45 minutes off.
Timezones are fun...
Can we go further? You bet! It has a changelog, and that changelog is stored in git, so commits to the tz changelog are diff^4: they are changes to the list of changes to the list of changes to the list of changes to UTC.
Now that I think of it, we could even stretch it one more level. In practice UTC is "realized" as a "best of" diff to atomic clocks in labs around the world, which are themselves diff against a fixed time point, as you pointed out. So that realization technically changes when the official UTC bulletin[1] is published by BIPM. So diff^6!
For anyone who doesn't know: Lord Howe Island is the last true paradise on Earth.
I went there on holidays a few years back based on two travel review recommendations. Both were by professional travellers that had been to pretty much everywhere, and both said it's the best place they've ever been. The reasoning was that every other tropical island has "something" wrong with it. Pushy locals trying to sell you stuff, sharks in the water, malaria, pollution, crime, poverty, or something.
Lord Howe is about as safe as it's possible to get, civilised beyond belief, pristine, unpolluted, etc...
It's one of the last places in the world with undamaged, unbleached coral reefs in protected waters. The diving there is just unbelievable, more beautiful than any Planet Earth documentary you've seen.
Birds nest on the beach, and you have to step over them gently because there's thousands of them and the juveniles can't fly yet.
I met the police officer of the island and pointedly asked him when was the last time he had to deal with crime.
"Crime... crime... let's see." he said, counting on his fingers slowly "Umm... seven years ago there was a domestic violence report because a tourist slapped his wife in an argument."
The hotel doors have no locks. There's $500 in cash in a tin next to a shack full of equipment on the beach with a "honesty system" rental price list sign next to it. The bloke selling you coke cans at the milk bar bought it with the $20 million he made in the stock market. Half the tourists go there by private plane. Ballmer's son took his super yacht there with a harem of models. And on, and on.
If you ever get the opportunity to visit: GO!
Sounds great apart from that bit.
https://www.atlasobscura.com/articles/the-extreme-daylight-s...
Of course offices, factories and even schools still use artificial lighting even during daylight hours. And now the energy use of artificial lighting is much lower than back when everything used filament.
A while ago Turkey switched to a different timezone and stopped doing DST for reasons and now everyone was waking up one hour early in winters. Considering how bad traffic is in larger cities that meant a lot of people will be waking up and going to work or school while it is still dark.
There was a survey in parts of the EU a few years ago about abolishing DST that came out largely in favor of abolishing it. In Germany one major source of debate around the issue was that the survey referred to the timezones as "winter time" and "summer time" and predictably more people said they would prefer permanent "summer time". An equivalent survey referring to the timezones as "standard time" and "daylight savings time" likely would have had the opposite result. I could imagine that Turkey picked EEST instead of EET for similar reasons.
Having had a job for six months over the winter where I spent the majority of the 8 hour work day underground, which at times meant I'd go for days without seeing proper sunlight, I agree that this is just miserable.
The key factor in the war was the blackout - street lighting was turned off for the duration and vehicle headlights were mostly covered over, to avoid providing easy targets for night bombing raids. This obviously hugely increased the hazards posed by the early sunsets under GMT.
https://www.timeanddate.com/astronomy/uk
Historically there was also Dublin mean time (UTC -00:25.21) and Warsaw mean time (UTC+1:24)
Somewhat related: Europe/Dublin has a negative DST offset. Irish DST runs through the European winter (i.e. the opposite of the other European timezones).
(More details here: https://github.com/golang/go/issues/56743#issuecomment-13157... )
Edit: To be clear: the quote is referring to a negative DST start, rather than a negative DST offset.
He has been to Lord Howe. Now I know why. He has a user account on HN. I will ask him if he wants to make an appearance here...
I found this pretty funny, but a spot on solution. The solar/calendar features of Emacs are surprisingly robust and easy to work with.
This one appears to have been published in the summer of 2024.
First off, the author starts off by talking about GMT and goes on to educate the reader how UTC is actually the current standard. Maybe it's just me but I thought this would be common knowledge by now, while the author frames this as some sort of a revelation.
Then there's the jab about The IERS breaking Wikipedia's css which just doesn't seem to happen on the two devices I opened it on, so I assumed that was the case prior to Wikipedia's redesign.
Minor things for sure, and the content itself is pretty timeless (heh).
I'm not sure what you mean, but this sounds wrong. The whole thing about leap second abolishment is to effectively disconnect UTC from UT1, i.e. allow DUT1 to grow unbounded and make UTC a fixed offset of TAI.
"Summer" in certain parts of the world, at least.
Thanks for the fun and informative blog post!
The named timezone is special as it is constant. The UTC offset timezone (e.g. "-05:00") and the shorthand name (e.g. "EST") is NOT constant over time for a given location, because of daylight savings time. "US/Eastern" flips between "-05:00" and "-05:00", as well as between "EDT" and "EST".
If you ask someone what their timezone is and offer them offsets or the short names, it causes confusion for everyone.
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 library that gets you the IANA identifier from timezone shapes.
https://github.com/RomanIakovlev/timeshape is maintained by a former coworker who could open source some of the work we did internally.
Can't remember the code for it now, had a lot of interesting timezone issues in a previous job.
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.
County is the smallest resolution one can reasonably use, but in terms of what timezones themselves follow, that would be metro areas. I.E. the Chicago metro area has its timezone and cities (or counties, if you will) that are part of that metro region, even when belonging to other states that largely follow a different time zone, follow the metropolis’ tz instead.
(Not arguing with you but clarifying the meaning of “follow” here.)
It's worse than that; Malheur County on the eastern border of Oregon is split between Pacific and Mountain time based on whether cities are more economically connected to Idaho or Nevada: https://en.wikipedia.org/wiki/Malheur_County,_Oregon#Time_zo...
The almanac gave nominal rules for the transitions. But there was a footnote explaining that these transitions had and will continue to be adjusted year to year due to Congressional intervention. I showed this to my boss and said, "If I could write an algorithm that predicted future votes of Congress, I would be a billionaire and could quit this engineering job."
I think in the end I coded the algorithm with the recent known transitions, and the nominal rules for future ones. What else could you do (this was before everyone was networked, and the code ran on standalone computers like a VAX).
I also learned that task of merging three sources of tracking data, each with its own validity and measurement degradation status, was an absolute nightmare. But still easier than predicting future actions of Congress.
> POSIX has positive signs west of Greenwich, but many people expect positive signs east of Greenwich. For example, TZ='Etc/GMT+4' uses the abbreviation "-04" and corresponds to 4 hours behind UT (i.e. west of Greenwich) even though many people would expect it to mean 4 hours ahead of UT (i.e. east of Greenwich).
I also did something similar earlier this year, though I used a geolocation service to translate address to lat/long coords, and then used lat/long to translate to timezone. (With shortcuts single-timezone states)
I ended up using this python library for lat/long -> timezone converstion:
https://github.com/jannikmi/timezonefinder
Which sources its data from here, which seems like a pretty high quality source:
https://github.com/evansiroky/timezone-boundary-builder/rele...
https://devblogs.microsoft.com/dotnet/handling-a-new-era-in-...
Honestly, the IT world has a certain amount of influence. There comes a time where we could collectively just say "no". No, you are not that special, use any of the already incredibly flexible options that you have.
Well, C23 mandates a byte is 8 bits, and POSIX 2024 disallows newlines in filename, so we do exercise that right times to times.
This might not 'mean much' to the computer, but it means a lot to the human. The computer uses it to communicate with the human and the humans between each other. When I arrange a meeting across timezones I will say CET 16.00 or ET3.00PM and they will understand it faster than saying how much offset we are from UCT.
I’m not sure that’s right! According to legend among metrologists I’ve talked to, “UTC” was chosen as a compromise candidate: it makes sense as an acronym in neither English nor French.
Which is not an acronym, btw, it's just styled in all caps, and is to be pronounced "iso" rather than "eye-ess-oh".
I convert the target TZ to UTC, using my local utility, then use my local TZ utility to convert from UTC to local.
But I write iOS software, so I have very solid local tools at hand. It might be more problematic, on, say, a webserver.
On a related note, I wrote this utility[0], some time ago. It uses the TZ map from the TZ Boundary Builder project[1].
Or if DST kicks in/out. No need to have the definitions change.
Of course every sane person runs their default system clock on UTC and lets users pick their own local time. That way cron always does the "right thing"(TM).
But what if your cronjob has an effect in the physical world, locally? E.g. open the parking gates every morning.
The world is inherently messy :-)
If you must run it as root, you can specify a CRON_TZ variable on a per-file basis, which will override the default.
Making a backup is usually reserved for the quietest hours of the morning, so that it does not compete as much for resources with the normal operation of the system; in my experience, the quietest hour is usually around 4:00 local time.
[0]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1019716
Seconds minutes and hours can change but the day cannot?
> mental math each time
Usually meetings are setup using an app and shared calendars should actually help here, a person can have meeting slots and out of office time, that should provide the same info. logistically I don't see that much of a difference from the current situation
The calendar day being aligned to the sleep/wake cycle and changing when most of the population is either asleep or at least might not terribly care about the actual date does help quite a bit.
> Usually meetings are setup using an app and shared calendars should actually help here, a person can have meeting slots and out of office time, that should provide the same info. logistically I don't see that much of a difference from the current situation
It'd also wreck any time references in any kinds of stories that aren't consumed locally. So every time I read/watch/listen to a story that isn't set where I live, I'd first have to look up the local time to make sense of any time references.
This led to decades (up to the mid-'00s) where Daylight Savings was the result of annual negotiations between religious and secular parties. It often caused problems when the decision wasn't made until juuuust before the transition date.
There are still exceptions built in to prevent Daylight Savings from ending on Rosh HaShanah, so that's probably the future stuff.
With about 13 hours of sunlight in the summer, split evenly around the mid-day, it comes down to 05h30 to 18h30 under light. There are many more people who would be out there to enjoy the sunlight between 18h30 and 19h30 than there are between 05h30 and 06h30.
Sunlight in the morning is useful. It's better for your sleep rhythms. It's safer for school children, etc.
And to be completely fair, I don't see that many more people "enjoying the sunlight" during the weekend when they have the entire day to do so. Like, what is the sun going down at 6 really preventing you from doing that you couldn't do otherwise?
> I really dislike this argument of "I'd rather enjoy the sun in the evening than in the morning"
> what is the sun going down at 6 really preventing you from doing
And it doesn't even matter what "most people" think. "Most people" in this case, would be wrong. Even if it were "most people" and not "most people whose opinions you've happened to remember on the subject because they happen to align with yours".
And it's going to get darker earlier in winter. That's just what it does. People are really just lamenting the lack of daylight hours in general. Because during the winter, few places have sunlight during 6pm and 7pm even if we kept DST year round. What they say they want is sunlight between 5pm and 6pm. And after the clocks roll back, it'll start getting dark soon after 5.
And once again, I ask, for what? Having the sun rise just after 6am is better for everyone. School kids waiting for the bus are safer, kids walking to school way safer. Better driving when you're waking up. Everything is more in line with your circadian rhythms, etc.
Decisions where the only effect is to align something arbitrary with people's preferences can only be made through appeal to the majority.
> And it doesn't even matter what "most people" think.
Yes. Yes it does.
> And it's going to get darker earlier in winter.
> School kids waiting for the bus are safer, kids walking to school way safer.
For the rest, let me give you an analogy. For several months this coming summer, I am going to give out an hour of free internet[0] each day. This won't interfere with the (paid) one that people are having otherwise. I'm not going to ask the question "would you prefer this hour to be between 05h30 and 06h30, or between 18h30 and 19h30?" but I am going to ask this question instead: What would the majority prefer, in your opinion?
[0] - any useful utility can be substituted: free hour of water, free hour of electricity, etc.
Sunrise will be at 7:12 tomorrow. Sunrise would be around 8am at the latest if we kept DST year-round.
There is less sun during the winter. That is how it works. Just in general.
Also, whenever we try "year-round DST" we go back to "spring-forward"/"fall-back" because it sucks. Everyone says they want it until they get it. Whereas Arizona has gotten rid of DST and we don't hear anything about them. They got rid of it in the 60s.
The nation should follow suit.
And all of this is outside the fact that time zones in general are more political than practical. Which is another reason people think they want year-round DST. It's because they're probably in the wrong time zone.
> DST actually makes most sense in 30-40 degrees of latitude.
Regarding your personal situation, I have no idea where you reside or what "the nation" is -- assuming US, I gather you have a "fall-back" change in three days, for a sunrise at 6:15am and up to 7am at the latest? If so, sounds like you've got it all figured out.
DST exists so that the sun doesn't rise around 5am. And that seems to be what the argument boils down to: "I don't want it bright too early".
The sun is going down around 8pm during DST on the 30th.
If you're arguing to keep doing what we're doing, you've managed to have an even wronger opinion than getting rid of Standard Time.
> DST exists so that the sun doesn't rise around 5am.
> And that seems to be what the argument boils down to: "I don't want it bright too early".
Here is a map of the offset between solar noon and civil noon[0]. The blue places have solar noon (sun in its highest position) before their local clocks show 12h00. The red places have solar noon after their clocks show that. The white places have it about the same time.
Several observations:
1. This is without DST. With DST, blue places turn red, and red places turn even more red.
2. The map is kinda outdated, the bluest most populous country -- Turkey -- moved an hour since, so now it's white at the east and red otherwise.
3. Greenland looks the size of Africa, which is a projection issue, in fact it's much smaller, and that's even before we talk about its minuscule population.
4. There are places like Recife in Brazil, where solar noon varies between 11h03 and 11h33, but they still have more than 12 hours of sunlight most of year, and never less than 11:45, so they hardly care.
5. The vast, vast majority of the world would rather have the solar noon after 12h00 -- meaning, more light in the evening than in the early morning. Santiago de Compostella has solar noon at 13h17 at the earliest and 14h40 at the latest, "relocating" around two hours.
6. The bluest city in the USA is probably Boston, and during standard time their solar noon is 11h30-11h59. During DST, it's 12h40-12h50.
[0] http://blog.poormansmath.net/images/SolarTimeVsStandardTimeV...
It’s status quo bias and loss aversion. Similar to how it would be better for the US to change their voting system, but it will never happen because it would disfavor one of the political parties who’d have to approve the change.
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.
https://www.kgw.com/article/news/nation-world/daylight-savin...
I'd prefer California to stay on standard time instead of staying on DST, so noon will be aligned with solar noon. (It is, right? I never actually checked.)
Take today, Nov 1st 2024, solar noon is at the following times in the State in these locations:
1pm, Crescent City: https://www.timeanddate.com/astronomy/@11788520
12:53pm, San Francisco: https://www.timeanddate.com/astronomy/usa/san-francisco
12:36pm, Los Angeles: https://www.timeanddate.com/astronomy/usa/los-angeles
12:32pm, San Diego: https://www.timeanddate.com/astronomy/usa/san-diego
It’s tempting to want to put stock in solar noon as the the thing the day should be aligned around, but honestly it’s probably overrated. Personally, I much prefer daylight savings time over standard time if I had to pick only one.
On July 8, 2013, the Knesset approved the bill to extend IDT even further. According to the bill, IDT will begin on the Friday before the last Sunday of March, and end on the last Sunday of October.[14]
So they don't want Daylight Savings Time to make it end even later than it already does.
It's also because of the fast day of Yom Kippur - people wanted the faster to end 1 hour earlier.
So they wanted DST to match up to those days - but that made the DST period too short, and led to the negotiations.
https://en.wikipedia.org/wiki/Time_in_the_State_of_Palestine
They have DST, but it's not on fixed dates, the government just announces each year when it's going to start and end. Sometimes with less that a week's notice, which must cause all kinds of interesting problems for people.
In a similar vein different people in Xinjiang in China observe entirely different timezones - Han Chinese observe Beijing time (because China is insane and uses one timezone despite spanning 5), while Uyghurs observe a local time 2 hours behind.
It’s a small show of resistance, which is sometimes all a people have if they have limited control of their own affairs.
In Palestine, this depends on my OS vendor managing to update the tz database in the short window before the official announcement and the decision coming into force. (I believe the tz database makes some assumptions based on past performance, but the government can change their mind any year.) If my OS does not update, I need to change my time zone manually to something that has the right UTC offset, and then I need to manually change back in the autumn, and I can never be 100% sure if any given computer shows the official time.
If your comment was about the 2019 change that almost all computers got wrong, this one was announced with 6 months of antecedence like most others.
Or maybe that 'most' ISO standards that are encountered by engineers are defining file-types.
I'm also a big fan of ISO-3166 though !
> Don’t let people bully you into thinking that just because something is complicated, it’s impossible. > This is because almost every standard (except ISO8601, whatever) is just a file, and you can read it.
In context, (my interpretation is that) "standard" includes things like The Time Zone Information Format [1], the GNU docs about TZ [2], etc. I think the idea is to say "the documents laying out the details of complicated things are still just documents, you can read them if you're interested and don't have to just see them as meant of domain experts. Some of them have barriers to access like the ISO documents, but even excepting those you have direct access to most everything you might want to understand, don't let the idea of standards intimidate you."
[1] https://www.rfc-editor.org/rfc/rfc8536.html [2] https://www.gnu.org/software/libc/manual/html_node/TZ-Variab...
You might find most standards for ~20 USD, but ISO8601 direct from iso.org will set you back 173 CHF (~200 USD) for part 1¹, 194 CHF (~220 USD) for part 2². For $20 you get only the latest amendments from them.
Meanwhile the Estonians will gladly sell you their version of part 1 for just under 30 USD.³
¹: https://www.iso.org/standard/70907.html
Historic data can be recorded. Rules like "last Sunday in October" or "first day of Ramadan" can be implemented and handled automatically (even if the current Unix implementations don’t do non-Gregorian calendars out-of-the-box). But there can be time zones whose DST rules are "if the groundhog sees its shadow, we start DST two weeks later, otherwise, there is no DST this year". Some countries actually implement this, except the groundhog is replaced by your friendly local regime.
Raku supports leap seconds. see https://docs.raku.org/type/Instant
It leads me to wonder. If it's all just an automated and finite offset, there's no reason for daylight savings policies to hew to 60 minutes adjustments.
Couldn't a nation decide to have a continuously changing offset throughout the year? It might make their offset lookup table substantially longer, but this could 'solve' daylight savings time It'd be adjusting all the time and you wouldn't notice, just you don't notice when leap seconds occur.
Those who rely on analog clocks might no longer adjust the same direction each time!
[1] See the map at https://en.wikipedia.org/wiki/Daylight_saving_time_by_countr...
Especially when everyone's half-hour blocks are misaligned with each other's so you can't even stack meetings efficiently.
We already have terms a few terms to tie events to solar time, for example, a park being open from dawn to dusk. And without time zones, we might come up with a few more.
For as long as clock sync for electronic devices has been common, I have suggested to anyone who would listen that we should adjust forward 10 minutes on the first Sunday of each month for six months, and then back 10 minutes on the first Sunday of the other six months. A ten minute change once a month is not only easier to adjust to (almost unoticeable), but if you miss it, it's not as big a deal as being off by an hour would be.
The primary time keeping device in my house is the clock on my stove; I wear old school watches a lot; and most of my cars are old and have old clocks in them. I can't be the only one, so multiply this by at least a few million other people in America alone.
Sure, you can tell everyone they need to ditch dumb clocks and replace them with internet-enabled smart clocks. But I think that's a far more onerous undertaking than just dealing with the fact that solar time and clock time are mismatched.
This ignores the easiest solution to daylight savings time.
Stop doing daylight savings time.
My preferred solution would be permanent standard time rather than permanent DST, but I'll take what I can get as long as we stop changing the clocks twice a year.
Other than considering current legally defined timezones as "legacy" definitions and then removing them for no reason other than to follow European fashion.
So, flexible, but managed by inflexible university types.
The only really important assumption not obviously present in TZif's data format is that when you go from a local time to a UTC time, there can only be up to two possibilities. A lot of software works on that assumption, for instance java.time.LocalDateTime has a withLaterOffsetAtOverlap():
https://docs.oracle.com/javase/8/docs/api/?java/time/LocalDa...
That implicitly assumes that whenever it's ambiguous what 2:30AM means, you can only have two possible solutions (pre- and post-DST). If a timezone were ever to manipulate its offsets so that there were three or more solutions (such as if they did a "fall back" at 2:00AM and then 2:15AM or something), a lot of stuff would be unable to represent that.
It would mean that the repeating meeting time would be at a slightly different local time every week.
It is correct that Greenland is part of Denmark, and Denmark is a member of EU. But Greenland voted several years ago to stay out of the EU.
But I think the analogy may be being stretched
Nothing is safe! Just wait til we get Star-Lord (Guardians of the Galaxy) accidentally facing off against some Jedi just so a writer can make some "Hans shot first" "inside" joke in some "way overshot the time travel to long ago in a galaxy far far away" plot...basically a movie to set up the joke in a trailer.
Sony has to release a Spider-Man movie every N months, or they lose the license, and will probably never get it again, since Marvel started making their own films and now they're part of Disney. This is why Sony keeps making reboot trilogies. Better to shovel something out than to lose the license forever. It does make a nice backstory for the Spider-Verse though.
Greenland is still part of the EU’s overseas countries and territories. It’s not like it’s in a different universe.
Time according to timezones measures the position of the sun. Except when we clearly decide with daylight savings time that we don’t care about the position of the sun, we just want it to be a certain time.
When the sun is directly over NYC it is usually 1pm or 2pm, depending on time of year, but 5pm or 6pm in London. Why? Are these events happening at different times? No, they are happening at the same time. Why do we use a different number for them?
Your “time zone” may decide that generally the workday is from 14:00 to 22:00. Why not? We already have second and third shift workers, so the idea of 9-5 is dead anyways.
When I schedule a meeting with someone in Tokyo and I am in NYC, is the meeting not happening at the same time? Wouldn’t it be easier to say “let’s do it at 13:00”? We still would need to figure out if people are awake and at work but we have to do that now while also figuring out daylight savings, so not only time but day of the year matters.
Heaven forbid you schedule a meeting or an event or a delivery or a stock trade and your time zone gets helpfully updated after you schedule the thing but before it happens. Better hope all the processes and software get that right or else!
And here is my favorite example I recently encountered: what is the speed of federal laws in the US? Say the tax brackets are rewritten for 2025, starting “January 1”. Cool, so if you work the NYE shift from 8pm to 4am in Chicago, is it the DC timezone that matters for your taxes? The local? If cannabis is legalized starting at midnight but you get arrested for possession at 11pm the day before in LA are you wrongfully detained or did you miss it by one hour?
Timezones are 19th century thinking. We can do better.
The solution is to just use UTC. That’s it. That means in NYC you’d get to work at 13:00 and go home at 21:00, which used to be 9am-5pm. That’s it. Your whole transition has been completed. The rest is just what your calendar says. Niece’s recital on Thursday at 19:00, beers with Greg at 23:00 on Friday, etc. It really isn’t hard to imagine.
I also think that your using the example of submarines -- notoriously an onerous lifestyle that very few are capable of living -- pretty much torpedoes your implicit suggestion that this would not be too much of a change.
You did that on porpoise I hope.
And the reason why people don’t just do that is because it is a network effect problem. We all need to buy into it. Like the metric system or driving on the same side of the road.
And people do this. Haven’t you seen people who routinely talk to people outside their timezones sign their email with their location and/or UTC work hours?
Okay. I work in Minneapolis and need to schedule a meeting with someone in London. How do I know what UTC time is during daylight hours for both participants? Well, we can use a formula that will tell us where the sun in the sky for a given longitude. But that's kind of a chore. So let's break ranges of longitude into zones and create a lookup table. Hang on a minute...
I've just traveled to Tokyo from Minneapolis. What time do I need to set my alarm to, to wake up an hour before most businesses open? Well, I can use trigonometry to figure out what UTC time the sun will rise at this location on Earth. But that's kind of a chore, so presumably each city will have an offset from UTC time that they all agree on to begin business hours. Hang on a minute...
And if you plan to meet your colleagues after dinner, would you say "see you tomorrow?".
You have plans to go to the theatre on Tuesday after work.
Is that 0100 on Tuesday (after finishing at 2300 on Monday) or 0100 on Wednesday (after finishing at 2300 on Tuesday)
Fine.. so I'm going to have a teleconference with a company in NYC. Due to what you wrote above I now have an idea of what UTC time window to plan for - after all, I want to be able to reach them during their working hours.
Then on Friday I have to schedule a teleconf with a company in Japan. When do they work, relative to UTC? You forgot to add that, so I have to find it somewhere.
Hm, wouldn't it be nice if my computer could keep track of the working hours everywhere in the world. Let's make a database of that.. There's just one issue: How is this any better than using the timezone system we already have? Using that, I can figure out the local time in those places, and I can safely assume that they'll at least be working from around 09:00 local time. Having to instead keep track of their working hours relative to UTC doesn't seem like much of an improvement to me.
Except for most people it is almost never a problem because most people aren’t scheduling phone calls or meetings with unfamiliar locations.
The benefit is obvious: things that happen at the same time have the same number associated with them. Just like we currently coordinate dates using a shared calendar, we coordinate times. And that has a local benefit as well. Aside from no more daylight savings time which we can achieve using other means, we also know when world events happen as they are being reported, we know when certain things take effect for countries that span multiple timezones now, we know the exact difference between any two given time points without asking “but where are they happening?”
Again, imagine that we had unified time and some country somewhere said “hey we are using the same format but doing our own variable offset from it”. That would be absolutely asinine. We are used to timezones and think they benefit us because of that familiarity. In reality we have had variable time even in the same timezones before and it was universally a bad idea that was shut down soon as people started traveling.
Oh and consider that due to cultural differences your example of scheduling meetings is already flawed: do you know if Tokyo wraps up the workday at 4pm or 6pm? Is there an hour or two hour lunch break in Barcelona? When do people actually come to work in Rome? Are banks open on Saturdays in Baghdad? Timezones do not solve these issues whatsoever so you still need to do the lookup of “when are people actually around” when scheduling a meeting outside of your culture.
2) If you want to let everybody in the world know when something specific happens (e.g. the launch of the first manned Mars mission), then you specify the time in UTC. But.. that's what we do already. Or at least those with some sense. There's still no need to force Joe Nobody to get to work at 14:00 (assuming a single world time zone) when the sun rises.. there's no advantage for people elsewhere in the world. You yourself argued that "most people aren't scheduling phone calls or meetings with unfamiliar locations". So, what's the advantage here?
3) I happen to use a calendar which is coordinated with others - it happens automatically, when they schedule something. And it has zero problem with the time - it's not just date. There's zero to gain by using UTC as localtime everywhere. That does nothing for the calendar.
4) Cultural differences in work hours: They absolutely exist. So what would having everybody use UTC help with? You still have to know those differences. It's even worse then, because if my stepson tells me "I have to work to 10AM" then I know it's late, for him. I know it instantly. If he had said "..have to work to 13 UTC" then I'm lost. I don't immediately see that he's actually working very late. I'll have to think "let's see.. he's in Tokyo, so that would be, hmm, this many hours difference from here.. is there an issue here? Oh wait, "you're working really late, will you be you okay?"
5) And that statement ".. most people aren't scheduling phone calls or meetings with unfamiliar locations". That's false. We're not in the 19th or even the 20th century anymore. The internet is a thing, and tons of people are in daily contact with people from all over the world. Just a moment ago I got a message from an airbnb guest, for example.
Also, and more importantly, "it's 5:00 somewhere!" would cease to be true.
That's why I only use Swatch™ Internet Beats [1] for timekeeping.
Now if you'll excuse me, I have a @583.32 meeting to get to.
If everyone used swatch times meetings would tend to start at intervals of 20, or maybe tens. Your meeting would start at @580 and last until @600 rather than 1300 to 1330 or whatever.
I guess what I mean is, I should write one.
On the other hand the transition from timezones to UTC has some challenges but the idea itself is very worth considering. What does this tell you?
Going back to that would make things more confusing. You take it for granted that we all use the same calendar. Nobody signs your paycheck using the Chinese calendar, right? You likely agree that the US using the imperial system is silly because wouldn’t the world be in a better place if we all used metric. So why the resistance to this?
You would have to give up many concepts that have local relevance, while gaining better understanding with non-local interlocutors. I think the balance depends on how many of your daily interactions happen at local or non-local scope.
Swatch tried it in the 90s and failed. Maybe we are more globalized today...
U.S. income taxes are calculated on an annual basis, not hourly, so that is not an issue. (Wages are taxed according to when they are paid, which is a specific point in time, not according to when they were earned). A better example is trying to figure which calendar (tax) year an item of income or deduction belongs to. On tax professional forums, there are occasional discussions about what happens if I make a business payment online just before New Year's Day begins, but the recipient doesn't "constructively receive" it until after (or similar scenarios involving time zone differences). Do I get a deduction for the old year, but they have income in the new year? (The best answer, of course, is to not wait until a few hours before a deadline to conduct business transactions of this type, but not every type of business has that choice available).
So in UTC-5 the day would end at 19:00 solar time. „Lets meet up for dinner on Thursday“ would become completely ambiguous, depending on the time. If you move dinner on Tuesday at 18:30 (23:30 UTC) to an hour later, it would be on Friday at 0:30 UTC.
Common types calendars would become quite useless, they would need to be different for each timezone. It doesn’t make sense to split the events of one solar day into multiple day-columns in a calendar.
The vast majority of people plan their life around solar days, they usually don’t have appointments planned that span over two calendar days.
Instead, the authors prefer to use their own domain language — source files with a compiler to a binary format with a reference parser implementation. The thrust of this article is that’s mostly good enough but their domain language doesn’t include lunar information.
The downside would be size and runtime efficiency. I’m guessing tzdata is built the way it is so that it can be extremely small and efficient rather than large and, computationally speaking, comprehensive. You can run it on an Arm M0 as well as an Apple M2.
1. Date and Time Programming
2. Debugging
You will encounter every possible issue and common bug when doing #1, leading naturally to #2.
Instead of picking the timezone with the correct offset and no DST, many people would adjust the time itself so the wrong timezone and the wrong unixtime cancel each other out so the clock "looks right". Not fun when you're doing math with timestamps, some of which are local and some come from the server.
>> Oh yeah the OCR on Japanese driving licenses pops out things like “平成 8”, that’s just how they sometimes say 1996 over there. That’s why we have this in the parser: eras = { "大正": 1912, "昭和": 1926, "平成": 1989 }
>> One of these days we’ll need to add "令和": 2019, but it hasn’t come up yet.
Taiwan also uses the ROC calendar[1] which is directly descended from the regnal calendars of imperial china.
But it's quaint that the Japanese name their year after one person, while us enlightened westerners simply use a calendar where it's simply the 2024th year of the, erm, hmmmph...
[1] https://en.wikipedia.org/wiki/Republic_of_China_calendar
https://en.m.wikipedia.org/wiki/Longitude_(book)
It's generally pretty well-regarded and closely related.
Why not switch to a normal 60 minute offset to UTC?
I think I actually heard on a podcast that some Mars rover mission team had to operate in shifts that were synchronized with Mars days.
It's a social problem and it calls for a social solution.
I know, there's a lot of disagreement around where the point in question is, but it would serve us well if more engineers were more assertive about stating their opinion on where it is.
We would need to form some kind of global union and push back together.
NIST does a lot of work behind the scenes in advanced technical fields. I wonder if it would help if there was a NIST publication enumerating common time and date keeping patterns, like we have for cryptography.
Also, are the users where they are because they want to be there, or because long ago some government or religious leader forced something through and they go along with it because of some kind of inertia?
If there was a Hall of Fame of OSS contributors - you would be in it sitting on top of a mountain. The Time Zone problem is a unique problem in that its not just a problem of whats the time in this location - its what was the time in this location 20, 50, 100 years ago. The level of scholarship and historical research you put into this library is really quite unmatched. Amazing folks you two. The whole world quite literally sits on the shoulders of you two giants.
“Daylight Saving Time was first suggested as a joke by Benjamin Franklin in his whimsical essay “An Economical Project for Diminishing the Cost of Light” published in the Journal de Paris (1784-04-26). Not everyone is happy with the results.” - Paul Eggert
There would be cultural effects as people in California now start work at 16:00, for example...
My understanding is that use of Xinjiang time has dropped recently because of the crack down on Uygurs and government forcing China time.
UTC is used globally when it makes sense, e.g. for the schedules of international radio broadcasts.
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.
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.
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)
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.
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
BIT (UTC-12) is better. Only positive offsets. Everyone on the same day.
The BIT anchor would not be changed for political reasons, unless approved by residents of Baker Island.
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.
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.
No-one cares if you set your watch to UTC regardless of your latlng. Meanwhile, the rest of us will just crack on with how we've always done it.
So I don't seriously purpose we do it, but it's fun to speculate how it could be. I think in an alternate reality where the whole world has the same hour, people would shudder at the crazy idea that every country has a different time on their clocks.
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.
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.
https://en.wikipedia.org/wiki/Daylight_saving_time#Terminolo...
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.) Work around the bug by not generating time stamps equal to -2**63. Come to think of it, time stamps before the Big Bang are physically suspect anyway, so don't generate time stamps before the Big Bang.
Soon afterwards, a separate commit disallowed leap seconds before the Big Bang.
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.
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."
Even if you mandate that wallclocks agreed everywhere on Earth, everyone would need a replacement to know when someone is likely to respond: Is it too late to call Grandpa? and: When should I schedule this business meeting?
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."
But i can not find it anymore. Anyone has an idea ? Is it gone completely?
Two different calendar systems are used, Gregorian and Julian.
These are nearly identical systems with Gregorian making a small
adjustment to the frequency of leap years; this facilitates
improved synchronization with solar events like the equinoxes.
The Gregorian calendar reform was introduced in 1582, but its
adoption continued up to 1923. By default cal uses the adoption
date of 3 Sept 1752. From that date forward the Gregorian
calendar is displayed; previous dates use the Julian calendar
system. 11 days were removed at the time of adoption to bring the
calendar in sync with solar events. So Sept 1752 has a mix of
Julian and Gregorian dates by which the 2nd is followed by the
14th (the 3rd through the 13th are absent).
There's UTC+14 in Micronesia: https://en.wikipedia.org/wiki/UTC%2B14:00
Also Antarctica/Troll: A timezone for a norwegian research station. https://en.wikipedia.org/wiki/Time_in_Norway
This is not true. Someone already noted that Raku supports leap seconds. I think this may be partly my fault, because Perl 5's most popular datetime library, `DateTime.pm`, supports leap seconds.
It's my fault because I created `DateTime.pm` and implemented its leap seconds support. In retrospect, this was almost certainly a mistake. Almost no one cares about leap seconds. It just produces all sorts of weird confusion. Like why does adding 60 seconds produce a different result than adding 1 minute, but only rarely?
And it makes the code _way_ more complicated, especially since I wanted to validate whether setting second to 60 was valid.
This seems simple. Why not just look up the leap second table and check? Well, the `DateTime` constructor takes time components (including `second => 60`) and _any_ time zone. So we have to convert the date/time passed to the constructor to UTC in order to do that lookup. But doing that conversion ... ended up involving values that include leap seconds because of historical reasons.
It's a huge mess for very little gain.
As to Raku, I think it's stdlib datetime library borrowed from Perl 5's `DateTime.pm` quite heavily so it inherits some of the same bad design decisions.
What was the thought process originally? Were you just too focused on the problem?
I find that if I'm too close to the problem and too focused for [arbitrary timeframe], this is the type of thing that happens. The joy of fixing something before it's broken takes over.
Of course, the _real_ correct solution is to split up a date/time library into a number of closely related classes/structs, and allow users to pick the one that meets their needs. So most folks would pick the leap second-free class, but a few would use the one with leap seconds baked in.
"An Instant is a particular moment in time measured in atomic seconds, with fractions. It is not tied to or aware of any epoch."
[1] https://tidepool.stoplight.io/docs/tidepool-api/branches/mas...
Something about this doesn't make sense. My understanding is that Ramadan can happen at any season of the year (imagine fasting all day in Greenland during the summer!) because the Islamic calendar doesn't insert intercalary months like many other "lunar" calendars do. Given that, what is the benefit of having a daylight savings time at all if it's tied to the lunar calendar? Isn't the idea of DST tied to day length?
> The tz database predicts future timestamps, and current predictions will be incorrect after future governments change the rules.
(The #10 slot varies according to source, but in general, Houston #4, San Antonio #7, Dallas #9, Austin #10. Fort Worth is nearly tied with Austin. Some sources claim Jacksonville, FL is #10, but they must be wrong...) :-)