21 ms·

UTC Is Enough for Everyone, Right?

• ATsch 8y ago
  The author expected this comment, but i'd still like to note that this website saturates at least one core of my laptop, more depending where I scroll.
  • sp332 8y ago
    There are tons of autoplaying videos, and each one takes a few % of my CPU. The biggest difference for me was the one just after the heading "Who needs December 30, 2011 anyway". Turning off autoplay (e.g. media.autoplay.enabled in Firefox) fixed it. You can still play each video by right-clicking on it.
    • vorg 8y ago
      The autoplaying videos are a pain, I couldn't find "media.autoplay.enabled" in my Preferences menu in Firefox, and this in the article calling me "clueless" doesn't help: > it is predictable that some clueless commenter on Hacker News will complain that this page has autoplaying video on it
      • sp332 8y ago
        Type about:config into the address bar and then search in there.
    • ATsch 8y ago
      yeah, that map zoom animation eats half a core for me
  • MBCook 8y ago
    The colors make it harder to read than necessary, and the text is bigger than I prefer on my phone. Reader mode didn’t work, so I gave up.
    • holman 8y ago
      Sorry about the lack of support for Reader mode; not entirely sure why that's happening (it's a pretty basic markup structure). If anyone's got thoughts on that, let me know and I'm happy to fix it. (Finna hang on to my videos, though! Life doesn't always need to be so one dimensional, particularly for one-offs like this.)
  • 314 8y ago
    But it does look gorgeous and it absolutely screams luxury layout and typesetting... so there’s that.
    • cryptonector 8y ago
      Huh, I guess I need to enable more scripts.
  • kalleboo 8y ago
    What browser is that? In Safari it seems to use negligible CPU when just text is on the screen, which goes up to maybe 20% of one core if one of the big videos is visible. It's also not enough to get the CPU to raise it's frequency/power consumption out of the idle state it is on, say, hacker news.
• setquk 8y ago
  Slightly off topic but I wonder how you handle time where dilation is present. For example if a spacecraft travels to mars and there is mars local time, plus time dilation from the journey, when does a transmission start from a reference frame? Not UTC related for sure! Or is it? And then what happens if someone else goes there in a different orbital pattern and the dilation is different. and then there is the question of how you would represent a recurring calendar entry between both places.
  • deleted 8y ago
    [deleted]
  • Retric 8y ago
    With care you can calculate UTC independent of any time dilation. Local system is mostly irrelevant in terms of UTC and we already deal with systems with different clocks due to leap seconds. Now you might care about communication lag, but nothing makes earth unique so you need to handle lag with arbitrary endpoints anyway.
  • oconnor663 8y ago
    If two spacecraft start going fast enough in different directions, they can disagree about what order two different events happened in. At that point, it's not enough to give an event a single time coordinate in some reference frame; you also need to know its position in space.
    • cryptonector 8y ago
      If you can compute time dilation, then you can map back to Earth time (UTC) or whatever, and use that in your communications. Otherwise you give up and use only local time in your communications. And if ever our interpid travelers meet again they can compare their clocks and determine dilation (which will not change the fact that they'll have observed events in different orders, but they'll understand this, hopefully).
    • dalore 8y ago
      So you would need to know both the position and momentum? Good luck with that.
• anothergoogler 8y ago
  Could people stop appropriating rap culture in their tech blogs (etc.) with patronizing garbage like "While I was initially building this talk, I found myself listening to the words of my absolute favorite modern-day philosopher: Nas"?
  • holman 8y ago
    Sorry you found it patronizing, I guess. Nas does great shit, though.
    • deleted 8y ago
      [deleted]
    • anothergoogler 8y ago
      I did, because you followed with "I’m not really sure what to take from all this, other than if Nas is really concerned about computer science and how it relates to time, then dammit, we should be concerned, too." The theme of the song you're talking about is lukewarm neoludditism. Not vague concern for computer science. And you're still doing it, infantilizing his music. He doesn't do "great shit," you could say he is a great lyricist, that Nastradamus is an underappreciated album (or, according to Nas, that it really is trash -- who's right?). But rap doesn't get a seat at the Adults' Table, it seems.
      • holman 8y ago
        Ah, totally see where you're going with this. Definitely my bad- I really should have ended this time programming post with a long treatise on hip hop styles and lyricism rather than toss in an obvious joke as a small aside to the longer point. (I am being patronizing here, fwiw.)
        • macintux 8y ago
          You think time has some weird edge cases, but then you get into a discussion about cultural appropriation and you realize how lucky you are to only be worrying about calendars.
• netsharc 8y ago
  > This stuff moves a lot, too: the tz database (also known as the Olson database), which is the listing of timezone rules we use as programmers to calm this chaos, gets updated many times a year. Without looking it up, I would say the last change happened when North Korea decided to sync its timezone with South Korea... or have they reverted that since Trump cancelled their summit?
  • holman 8y ago
    I think it's one of the more recent changes. It's actually pretty cool- all of this is discussed on the tz mailing list, so you can see how it all works yourself! https://mm.icann.org/pipermail/tz/ https://mm.icann.org/pipermail/tz/
    • politelemon 8y ago
      Thanks that's a great link. Indeed as you said I'm learning quite a lot about how it works just from this thread which started about the Western Greenland timezone! https://mm.icann.org/pipermail/tz/2017-December/025606.html https://mm.icann.org/pipermail/tz/2017-December/025606.html
  • masklinn 8y ago
    Checking 2018e, that is in fact the last change to the database, though they also updated some past timestamps: > From 1994 through 2017 Namibia observed DST in winter, not summer. > In 1946/7 Czechoslovakia also observed negative DST in winter. 2018d had a change to palestine's DST date (a week earlier than usual), Casey Station moving from +11 to +08 and a few other historical changes/fixes.
    • madcaptenor 8y ago
      To clarify: Namibia had negative DST in (southern hemisphere) winter. They had UTC+1 in the winter (April to September) and UTC+2 in the summer. Now they're UTC+2 year-round, aligned with South Africa. The reason seems to be historical - if you're on year-round UTC+2, and you want to be on UTC+1 in winter/UTC+2 in summer, it's easier to say "we're setting the clocks back an hour in winter" than to say "we're setting the clocks back an hour year-round... and then forward an hour in summer."
• blunte 8y ago
  Sadly I didn't have enough time to read the whole article... But I wish we could all just use one time. For some, midday would be 12, and for others it might be 19, but we already all use the same dates regardless of whether February is winter for one location or summer for another.
  • masklinn 8y ago
    Congratulation you jokester, you're the second paragraph of the "Timezones" section.
  • hinkley 8y ago
    Maybe when we are an interplanetary civilization, but then only if the balance of financial power shifts off of Earth. We are still trying to dig ourselves out of old systems where “today” and “yesterday” are logically different and we hide the problems by assuming most users are asleep at midnight. Most new systems don’t have this problem but older ones equate “tomorrow” with “start of business the day after tomorrow”.
  • snarf21 8y ago
    I completely agree. It isn't like we don't deal with this already planning a flight to/from Vegas or having a call with someone on the other coast. Plus we can also get rid of the abomination that is daylight savings. I think there is a simple plan that isn't disruptive. Simply require that all times be listed in both formats. For example, 9:00 am EDT (13:00 UTC) for all printed times on all signs, etc. moving forward from some day in the future. Eventually, we can drop the first as people adjust. (This is already how we re-number or rename highway exits)
    • blunte 8y ago
      Until we get rid of daylight savings times everywhere, dual representations will still require a lot of effort to provide.
    • henrikschroder 8y ago
      > Eventually, we can drop the first as people adjust. This doesn't help in any way, shape or form. You have pissed off billions of people who have had to re-learn custom times for things, you have caused the weekday to flip in the middle of the day for billions of people, and you STILL haven't solved the problem of "Can I call Uncle Steve in Melbourne, or is he sleeping right now?" https://qntm.org/abolish https://qntm.org/abolish
• masklinn 8y ago
  Having dealt with that crap… that should be an interesting read scroll scroll scroll nod nod nod scroll scroll scroll > Recurring events Whelp, shit just got very very real, and I actually disagree with Zach here: > If someone held a gun to your head and demanded in the next week you either 1) programmed a comprehensive system that included full support for recurring events, or 2) invent full-scale ready-to-go-to-market cold fusion, then you should abolutely start brushing up on atomic physics. You should just beat yourself with the gun (or whatever the nearest heavy implement is) immediately, no cause to prolong the pain, you're not Harold.
  • scruple 8y ago
    Yeah. I've lived through this scenario (implement recurring events based on a calendar system in very little time). And even though I definitely had a longer runway than a week (a whole month! on top of the work that I already had on my plate), I would still agree to take the beating immediately if I was presented with that situation again. Yeah, sure, I "got it done" but it was very challenging to maintain for a while. And, of course, I learned well after the fact that what I had designed and implemented had basically, rather poorly, implemented some existing solution / FOSS library (I had essentially written some pieces of the Ruby gem ice_cube without realizing it) that I hadn't been able to find via Google at the time.
• akkartik 8y ago
  "Did you hear about the clock maker who was the first to add a second hand to a clock? His first prototype was a complete failure, but he got it working the second time." Very funny, but here's the real reason (https://www.etymonline.com/word/second https://www.etymonline.com/word/second): > second (n) from Old French seconde, from Medieval Latin secunda, short for secunda pars minuta, "second diminished part," the result of the second division of the hour by sixty (the first being the "prime minute," now called the minute). Etymonline.com is awesome. I use it several times a day.
  • agumonkey 8y ago
    One of my most visited and favorited website. Donate to the author.
    • aeorgnoieang 8y ago
      The author's bio is great: - [bio](https://www.etymonline.com/columns/post/bio?ref=etymonline_footer https://www.etymonline.com/columns/post/bio?ref=etymonline_f...)
• zeveb 8y ago
  > Base ten is lit and doing everything in twelve feels so uncivilized … It's actually the reverse: base twelve is more elegant than base ten[0]. The only reason we think otherwise is that we're used to using base ten. 0: ½ in base twelve is .6; ⅓ in base twelve is .4, not .333333…; ¼ is .3; 1/6 is .2, not .166667
  • holman 8y ago
    I actually had something similar to this in my notes but didn't get around to adding it. Basically, 60 minutes seems kind of arbitrary for an entire system of time (at least to me!) and then I realized that once you split it down into half, thirds, quarters, etc., it's basically the best numbers to use for informal conversations about time. That was pretty illuminating when I read about that; thanks for pointing it out here!
    • ttsda 8y ago
      They're called Highly Composite Numbers (or anti-primes) [1], meaning they have more divisors than any smaller number. [1] https://en.wikipedia.org/wiki/Highly_composite_number https://en.wikipedia.org/wiki/Highly_composite_number
• pquerna 8y ago
  Love this article, but one thing it skipped on was more in-depth on Leap Seconds. You see, UTC, is kinda like another human-made-up timezone. Humans made up some rules, and UTC is a 37 second offset from TAI / International Atomic Time: https://en.wikipedia.org/wiki/International_Atomic_Time https://en.wikipedia.org/wiki/International_Atomic_Time
  • milesvp 8y ago
    Right? And that that 37 second offset will change from year to year? I was waiting for the bombshell, that some minutes actually have 61 seconds in them, and some have 59 seconds (though it occurs to me that I don't know if astronomers ever add or subtract more than a second for any given clock adjustment).
    • welterde 8y ago
      The goal is to always keep UTC within one second of UT1. Short of very drastic events I don't think it will ever be neccessary to introduce more than one leapseconds in a fairly long time interval. And even if it was, I would think that they would do seperate leapseconds events some time apart.
      • jandrese 8y ago
        There are two official primary times a Leap Second can occur. December 31 and June 30. There are provisions for more slots, but they're not really expected to ever be used. Like most things associated with time Leap Seconds are a huge headache to implement properly on computers. If you want some fun watch what various NTP servers around the world do when Leap Seconds roll around. You will see clocks that start to drift for 15 minutes before jumping to the right time, some that wait until 8AM local time on the following day to correct, and some that just go crazy. And of course you have Google's clock smearing across most of a day. IIRC there was one major earthquake that caused a sooner than expected Leap Second adjustment. Fun fact: GPS, NTP, and many similar timing formats have flags in the signal that warn clients of upcoming leap second events. Few receivers pay attention to them however.
• 0x0 8y ago
  So the article seems to imply you should store all timestamps as UTC (with an additional timezone string ID). But for events in the future that needs to happen on a specific "wall clock point in time", it might be better to actually store the yyyy-mm-dd hh:mm:ss as a string with a timezone next to it, because timezones can and do change often unpredictably. If you pre-calculate what "4.00pm next August 1st" is as a UTC timestamp today, and the timezone rules are updated between now and then, your UTC timestamp may end up being incorrect. I guess you could have an additional "precalculated-utc-timestamp" column but regularly re-calculate this from the "yyyy-mm-dd hh:mm:ss + timezoneID" (especially when you upgrade your Olson tzdata).
  • draw_down 8y ago
    Sure... except, what is "future"? Or rather, how do we know which things are in the future?
  • cryptonector 8y ago
    Yes, you have to periodically recompute times. For example, if you store time in TAI then you'll have to recompute all other future times as leap seconds are announced.
    • hanikesn 8y ago
      I don't think I ever heard of anyone (besides scientists) to store timestamps in TAI. Though Ada supports leap second calculations in the standard library: http://www.adaic.org/resources/add_content/standards/05rat/html/Rat-7-3.html http://www.adaic.org/resources/add_content/standards/05rat/h...
      • cryptonector 8y ago
        Dealing with time well into the future is rough because of the unknown timezone changes and unknown leap seconds. There's not much you can do. Computing future times in TAI from user inputs in wall clock time is fraught, so I guess you can't store TAI in those cases. For a calendar app, since users want to deal in wall clock time, you have to store time with timezone and with leap seconds (so UTC + time zone). And you have to store timezone, not offset to UTC -- timezones can change. At least internally, however, dealing in TAI can be helpful[0]. Also, IIRC there's a proposal to redefine UTC as without leap seconds[1]... That scares me. Users really need wall clock time. The continued existence of TAI was questioned in a 2007 letter from the BIPM to the ITU-R which stated "In the case of a redefinition of UTC without leap seconds, the CCTF would consider discussing the possibility of suppressing TAI, as it would remain parallel to the continuous UTC."[16] [0] ttps://cr.yp.to/time.html [1] https://en.wikipedia.org/wiki/International_Atomic_Time https://en.wikipedia.org/wiki/International_Atomic_Time
• lowq 8y ago
  11/10 - xkcd had alt text
• masklinn 8y ago
  > The Happy Monday System, which honestly I just loved based on the name of it alone. Shows how Japan has moved their holidays schedules around just to make people happier with a longer weekend. In countries with significant amounts of legal leaves (e.g. most of europe), tuesdays and thursdays are also very nice as "burning" a single leave day provides for a 4 days weekend (and 3 days week). French even has an expression for this: "faire le pont" (bridging between holiday and weekend).
  • madcaptenor 8y ago
    Independence Day, in the USA, is always celebrated on July 4. One year in seven this creates some awkwardness: which weekend is "Fourth of July weekend" if the 4th of July is a Wednesday? 2012: https://www.theatlantic.com/national/archive/2012/07/seriously-how-annoying-midweek-fourth-july/326316/ https://www.theatlantic.com/national/archive/2012/07/serious... 2007: https://www.inc.com/news/articles/200706/independence.html https://www.inc.com/news/articles/200706/independence.html 1990: https://www.nytimes.com/1990/07/04/garden/and-thank-god-it-s-wednesday.html https://www.nytimes.com/1990/07/04/garden/and-thank-god-it-s... (NYT)
  • icebraining 8y ago
    In Portugal we have the same expression (probably copied from French). It gives rise to some conversations that sound funny when translated, such as "do you have bridge this Friday?"
• _asummers 8y ago
  Typo note to author: therefor should be therefore.
  • rauhl 8y ago
    I know that ‘therefore’ is the way it’s normally spelled, but I always thought it was goofy: all the other there-compounds (which are cognate to German’s da-compounds) & where-compounds (cognate to German’s wo-compounds) don’t change the spelling of their prepositions: thereafter, thereon, thereat, whereafter, whereon, whereat &c. I also don’t understand why modern English doesn’t take advantage of them like modern German does.
• hinkley 8y ago
  I have been thinking a lot lately that we are trying to solve class of XY Problem. Universal time is in part about trying to order events in a strict order. Probelm is, nobody observed that order. Later we infer things about the system based on this chronology but it’s completely fictitious and we have to stretch our brains to explain the state of the system. The Java Memory Model, and subsequently several other languages, agreed on “happens before” semantics. We don’t care what order certain things occurred in as long as these key events happen in the right order. Because those events cause the other events or are caused by them. Some transactional models have a flavor of this as well. This write happened based on a decision made by observing all of the transactions up to N, which may or may not result in a rollback because N+1 overwrote a read value. I can’t help thinking that our logs should show something like “customer saw their balance was $102.75 and withdrew $100, and on another server a payment for $55 was honored around the same time, which is why they are now overdrawn”. The two events were independent, and maybe we should remember them the way the distributed system experienced them. Or maybe that’s even harder to reason about than the fiction we use now...
  • coldacid 8y ago
    If people could regularly reason like that, asynchronous programming wouldn't be such a pain in the ass.
    • hinkley 8y ago
      My knee jerk response is “Events in a git repository are partially ordered. And we have a visualization for that.” And then I recall how often people misunderstand a git diagram with more than three independent chains of events. Still doesn’t rule out bad tools but it doesn’t paint a good prognosis.
  • TylerE 8y ago
    Every bank I've ever been a sucker-err-customer of seemed to use whichever order results in the most fees. Not the only reason I use a credit union these days.
    • 8y ago
• da_chicken 8y ago
  > Properly storing timezone-aware times I'd just like to point out that a lot of RDBMSs support storing date and time alongside timezone information directly without using two separate fields. SQL Server has datetimeoffset, PostgreSQL has timestamp with time zone, and Oracle has timestamp with time zone. I think MySQL does as well, but I seem to recall something strange about it. Or maybe that's just me expecting MySQL to do something weird. Similarly, most programming languages have support for datetimes with time zones. It's still all a huge pain in the butt, but you don't need to use two fields and ensure that you use both all the time. Also, you can meaningfully compare datetimes within the same database without translating the timezone if its all in one field. Also, of course, remember that a even a time with timezone without a date attached to it is inherently ambiguous.
  • jeremyevans 8y ago
    > I'd just like to point out that a lot of RDBMSs support storing date and time alongside timezone information directly without using two separate fields. SQL Server has datetimeoffset, PostgreSQL has timestamp with time zone, and Oracle has timestamp with time zone. PostgreSQL's "timestamp with time zone" doesn't store timezone, it converts the time to UTC and stores that, and on retrieval converts the value to the connection's time zone.
    • ssijak 8y ago
      That sounds dumb (if column type is called like that text in the quotes)
      • rspeele 8y ago
        It is, and it is.
      • Erwin 8y ago
        SQL data types have some verbose names, like "NATIONAL CHARACTER VARYING (20)". PG adds a "TIMESTAMPTZ" as alias for "TIMESTAMP WITH TIME ZONE" (which I'm not sure whether is a sql ansi standard type or just convention).
• coldacid 8y ago
  I thought the 12-hour thing came from Mesopotamia, not Egypt.
• ssijak 8y ago
  This is tougher to get then time in general relativity...
  • peterwwillis 8y ago
    I always figured if spacetime was relative, why don't we just report the location we are at and that local time? If I know I was in Lower Manhattan at 2:00pm on November 19th, 2007, somebody else can just do a little math to figure out when that actually was compared to their own local time and place. All times are interpretive. UTC just seems like a giant hack to try to avoid the interpretation.
    • quickthrower2 8y ago
      Who's clock is correct though.
      • peterwwillis 8y ago
        Whatever the town clock is set to. I'm surprised the author didn't mention Railway time. The standardization of time did not begin in the USA in 1883, it began in England in 1840. Before then, sundials, and later a local mean time, was used to determine local time. Railroads published almanacs with different local times, and instructions on how to reset a watch along a route to know what time it was. However, the small changes in time, or even differently timed sunsets, created problems and accidents, so to solve this they used the newly invented telegraph service along the railroad's telegraphic lines to synchronize clocks to the official time at Greenwich. This method to synchronize time then spread to India and then the United States. It was in 1880 that a law passed in Great Britain finally made the new time official across the whole country. However, as the attached article shows, neither GMT nor UTC solve everything. When humans are involved there will always be mistakes unless things are simplified for them.
• ris 8y ago
  If you want a technical audience to read your page, get rid of the videos and unnecessary animations.
  • ealhad 8y ago
    Isn't that exactly what reader mode is for?
  • saagarjha 8y ago
    > It’s so predictable that developers will pooh-pooh having to write timezone code, almost as much as it is predictable that some clueless commenter on Hacker News will complain that this page has autoplaying video on it. And then someone will calmly quote this passage in response, quietly pleased with themselves that the initial commenter was rude and certainly didn’t read the post at all. Then a third person will chime in on the thread saying the author was playing you all like a fiddle anyway, and the real problem is that the post was way too long to start with. I guess I get to play the part of the second person…
    • zifnab06 8y ago
      The author played us all like a fiddle.
      • mildweed 8y ago
        It was too long to start with
      • exikyut 8y ago
        He's playing my laptop like a fiddle, too, a really high-pitched one: all the videos are keeping the CPU at 100% CPU so I had to downclock everything to keep the system below 64°C. So: the first time I ever found a paragraph like the one the GP has quoted, happened on the same site I've ever been on where the autoplaying videos are making my whole system (including typing this comment) lag worse than any other site I've been on. At least it gave me one good idea for the Extension I'm Making One Day™: watch the CPU and if the current page is killing it and it has autoplaying videos and/or CSS animations, automatically kill both. In the meantime, I had to close the article as it was unreadable. (Wow, getting my low typing latency back is wonderful!)
• koliber 8y ago
  Four days ago I saw an excellent presentation about the trickeries of time, dates, and timezones at DjangoCon Europe. It was by Russell Keith-Magee and is short, to the point, and super informative: https://www.youtube.com/watch?v=qabriMQ1SYs https://www.youtube.com/watch?v=qabriMQ1SYs I recently ran into a completely novel time bug while working with Excel file for GoodGrids. In Excel files, date and time values are stored as epoch time. But you can not tell what time a particular number represents until you check whether the file was made with Excel on Windows or on the Mac. It turns out, the developers chose a different start of the epoch on these two platforms. A while ago I came to the conclusion that time is simple from any one perspective, but complicated when you try to handle all possible perspective. Try to explain the complexities of time to someone who does not travel, resides in the same timezone all of their life, and does not need to coordinate with anyone outside of their timezone. For them, the rules that govern time are pretty easy.
• sly010 8y ago
  Obviously it all depends on the application: Birthdays (as the article mentioned) are not points in time and mean different things depending on where you are, so best stored as a year-month-day combo without any zone information. Past times are not that big of an issue actually, just use UTC and convert to local time to display, but calendars schedule for the future, and you can't always calculate a future time in UTC. In e.g. distributed system where monotony and ordering is important UT1 would actually be even better than UTC, as UTC has occasional jumps (hence the workarounds, like googles skewed NTP)
• mey 8y ago
  I really think we need a standard way to handle linear time that is not effected by leap seconds but can be mapped between back to calendar time (UTC) The Unix Epoch does not handle leap seconds (time just rewinds). Google's time smearing approach is a great hack, but trades one issue for another. This is a niche case in high resolution time, auditing and security considerations.
• lbj 8y ago
  I was blown away by the design on this blog, super slick!
  • Washuu 8y ago
    Yet over here I am finding the design to be terrible, lacking good user experience, and overall terrible to use.
• yxhuvud 8y ago
  That was an efficient way to heat a battery.
  • lucb1e 8y ago
    Same here. About a quarter way through the article I figured out what the hell my system was running; then, halfway through, I had enough. I disabled Javascript and reloaded the page. No dice. Page renders perfectly including videos. I scrolled a little faster and skipped parts from there on.
• emodendroket 8y ago
  > Probably around this time your first boss's ancestors were also discovering minutes as a good way to make sure your ancestors got to work on time: "You're exactly 56 minutes late today, Holman, what the fuck is wrong with you? Go shave the sheep!" OK, I guess this is a joke, but this actually began to happen during the Industrial Revolution, when factory owners were obliged, as part of worker training, to teach workers how to read a clock.
• nsxwolf 8y ago
  In my 20 years of working with software and distributed architectures, no problems have been harder than working with time zones and calendars. It is truly nightmarish stuff. I am convinced you could run a very profitable consultancy specializing in debugging date and time related problems in people's systems.
  • zrobotics 8y ago
    That would be profitable, but I'm not convinced anyone could stomach that job without going insane. Maybe a year if you were extremely hardy, but I'd be running for the padded cell after 3 months of dealing with nothing else.
  • chopin 8y ago
    Character encoding can be equally scary.
• slater 8y ago
  We could've all switched to Swatch™ Internet .Beat Time™ by now, but nooooo, we wanna stick with all this mess instead! :P
• jheriko 8y ago
  never worked on spacecraft then ... ;) TAI if you can work it out :)
• paulie_a 8y ago
  The one that has been a problem for me is comparing hourly breakdowns for DST. How do you compare last week vs a day with 25 hours in it
  • holman 8y ago
    There's a lot of really weird edge cases like that. A lot of the times you sort of have to make a judgement call. There are cases where you have to make a judgement call, one way or another. Take the case where I invite you to a weekly meeting at 2pm. You live in a place with DST, I don't. DST happens and... is the meeting at 2pm, or 3pm, or what? Google Calendar (and many others) basically say whoever owns the event wins, so our "regular" meeting time would track however you go through life (at least in terms of DST), so times might change for you but not me, and vice versa. Anyway, yeah, there's some really odd interactions once you start digging deeper.
• quickthrower2 8y ago
  Sound track to accompany article: https://www.youtube.com/watch?v=JwYX52BP2Sk https://www.youtube.com/watch?v=JwYX52BP2Sk
• Pyxl101 8y ago
  > Egypt was the first ones to really start doing this: they had a duodecimal system already, so that's why it was split as base twelve, or our two parts of twelve hours in a day. If you're like me and immediately said ohhhhhhhhhhhh, so THAT'S why there's twelve hours in a day! The reason why we use numbers like 12 and 60 and 360 in time and length, from ancient times onwards to today, is because these numbers have many divisors, meaning that they can be divided many different ways without needing decimals. 12 can be divided by 1, 2, 3, 4, 6, 12 (i.e., it can be divided in half, into thirds, fourths, sixths). By comparison, you can't cleanly divide 10 into thirds or fourths without using decimals. 60 can be divided a whole bunch of ways: it can be divided by 1,2,3,4,5,6,10,12,15,20,30,60. The same is true for 360 (e.g. degrees in a circle). Even in the modern era, where we understand decimals and everyone is trained on them, it's convenient to be able to perform common operations on common units without having to involve decimals. It's convenient that an hour can be divided into three 20-minute periods, or two 30-minute periods, or six 10-minute periods, and so on.
• hyeomans 8y ago
  Great description of pains I've been feeling the last 5 years in my daily life. Just one comment on colors, I can read the whole post but when I switch or look somewhere else my eyes have a hard time adjusting to all those crazy colors I just saw. Maybe I'm broken.
  • jobigoud 8y ago
    Cone receptors saturate when you look at the same hue for a period of time and loose sensitivity for a while. It's known as retinal fatigue or cone fatigue and causes after images. It's normal and used in several optical illusions.
• erpellan 8y ago
  Postgres have done a really good job here. It not only understands offsets (which most devs think are timezones) it also understands timezones. What's the difference? GMT-8 is an offset. America/New_York is a timezone. This becomes important when you want to schedule a meeting on the east coast of the USA in April - Europe and the US change DST on different dates. But if you tell postgres you want a time in a particular zone it will do the calculation correctly. If you use an offset you might turn up an hour late.
  • jobigoud 8y ago
    What's the point of unqualified offsets like that anyway? You either use UTC or a local time in the appropriate tz.
    • x1798DE 8y ago
      They are useful for when you want the semantics of UTC but still a human readable time. One example is logs that people will actually read. People have a hard time doing mental math but 14:00-05:00 is just as valid as 19:00+00:00 and easier for people in Eastern Time. It's also useful for disambiguating a local time: 2018-11-04T01:45-05:00 America/New_York 2018-11-04T01:45-04:00 America/New_York That said, I do think they are mostly around for less noble reasons: they are way easier to serialize than actual time zone rules.
    • zaarn 8y ago
      Useful when you need to store the offset of a specific event in the past where the timezone data doesn't matter. Especially logs since you want to know when it occured, so you store unqualified offset so the DoS attack doesn't suddenly happen an hour earlier than it says in the logs if DST happens between attack and the admin reading the log.
  • masklinn 8y ago
    How do you update the tzdb?
    • aeorgnoieang 8y ago
• SaladFork 8y ago
  My favorite date quirk not mentioned in the article or here yet is the month of September 1752. If you're on a *nix/Mac machine, try this command: $ cal 9 1752 What you'll see is: September 1752 Su Mo Tu We Th Fr Sa 1 2 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 No, there's not a bug in `cal`, this is correct ;)
  • rbosinger 8y ago
    That was fun. So what happened in 1752? edit: I should have searched (http://mentalfloss.com/article/51370/why-our-calendars-skipped-11-days-1752 http://mentalfloss.com/article/51370/why-our-calendars-skipp...)
• mjpuser 8y ago
  I would be interested to see a proposal for a standard for establishing planetary time with the feature that you can easily convert from one planet to the other, but I have no idea how you would do that. What happens when we move to Mars with Elon? UTC would not be practical.
• nixpulvis 8y ago
  Elementary my dear Watson. In all seriousness, a great collection of advice on time. Bookmarked.
• bkovacev 8y ago
  > Definitely check it out if you get really excited about reading whitepapers. Also get yourself checked out if that’s actually the case. Highlight of the article! Even though I disagree with certain bits, the article in itself helps explain how to think about programming time in a project.
• deleted 8y ago
  [deleted]
• mark-r 8y ago
  The Olson database is great, but I wish it included more cities. I hate having to know the mapping from city to time zone and time zone to city. Quick, what's the zone to use for Columbus, Ohio?
• marshray 8y ago
  There are only two types of time systems: 1. TAI, and systems that have a fixed 1-to-1 mapping to it (e.g., GPS). 2. Systems that are generally unable to calculate how many seconds will elapse until your next birthday. UTC is in this category. Articles like this spend a lot of time on the varying degrees of insanity in category 2. But I would rather start with category 1 and negotiate any additional complexity from there.
  • TorKlingberg 8y ago
    The exact start of my birthday depends on where will be at the time. It starts and ends at midnight in the current timezone. With some clever time zone jumping my birthday could start twice or more in the same year. Also if I was born on February 29, you need to move it Feb 28 or March 1 on non-leap years.
• kstenerud 8y ago
  Wow... this site completely freezes my mobile browser dead in its tracks.
• john00088876 8y ago
  If you think calendar apps are a pain try television broadcast automation... frame accuracy instead of per second, with fractional frame rates (29.97, 23.98, fps) and a mix of content of different frame rates on the same playlist and conversion to different frame rate on the way out, plus operators in a different timezone than the channel and the need to handle timezone changes without messing things up on air. I have nothing to do with it but this is an open source automation project I have bookmarked with some of those functions: https://github.com/jaskie/PlayoutAutomation/blob/develop/TAS.Common/SMPTETimecodeExtensions.cs https://github.com/jaskie/PlayoutAutomation/blob/develop/TAS... Lots of hassles.
• rbonvall 8y ago
  Ironically, the article is dated "Spring 2018", which for half the planet doesn't happen yet :)
• ninjakeyboard 8y ago
  We have had some issues with timezones and DST... Time is not fun. Funny well written article - thanks!
• dpark 8y ago
  > 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.
  • Jedd 8y ago
    > 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.
    • Iv 8y ago
      > dozeine. French nitpicker here. We now write it "douzaine" but spellings have changed through the ages.
      • Hemospectrum 8y ago
        Yep. Most of the "French" words in English (beef, butcher, danger, very, act...) actually come from dialects brought over by the Normans when they conquered England in 1066. That's closer on the timeline to Latin than modern French.
• foobar1962 8y ago
  > [1883] ... a bunch of rich, white railroad tycoons met at a fancy Chicago hotel to agree on a standard timezone so their trains would work better together... The Brits did this for their railroad in 1847. Time balls were used to synchronise clocks before telegraph and radio. https://en.wikipedia.org/wiki/Time_ball https://en.wikipedia.org/wiki/Time_ball On clock accuracy, I was reading last night about time dilation due to gravity, and the difference in time rates from points less than one meter apart in height on earth have been experimentally verified.
  • cup-of-tea 8y ago
    Indeed, I thought it was well known that Britain was the first to standardise time and that it was done for the railway.
• tlrobinson 8y ago
  > (My all-time fave is RFC 2606, thanks for asking! I’m in awe of that absolute unit. Where would we be without that banger? We’d be in complete fucking chaos, that’s where.) RFC 2606 ("Reserved Top Level DNS Names") not RFC 2616 ("Hypertext Transfer Protocol -- HTTP/1.1")? I would have gone with the latter. Related: I just noticed Cloudflare's DNS service (1.1.1.1) follows the suggestion in RFC 2606 and resolves *.localhost to 127.0.0.1. That can be handy for local web development etc. There are some other wildcard domains that resolve to 127.0.01 but I usually can't remember them.
  • meta_AU 8y ago
    xip.io is one service that will wildcard for any IP address.
  • JdeBP 8y ago
    Enjoy RFC 6761.
• InclinedPlane 8y ago
  Lemme tell you about a fun little bug in the TFS Build system. You can create build definitions, you can set the schedule for those builds. You can, for example, schedule builds that run at a certain time of day every day (or every weekday or every Tuesday, or whatever). That build information is then stored in an internal representation which is actually used for scheduling. And that internal representation, it uses UTC times. Can you see the bug here already? So, your build system will be scheduling daily builds at the same time every day, and then suddenly after a DST change those builds will be an hour off from when you expect them. But here's the even more fun part. If you simply happen to edit and then save one build definition after the DST switch then it'll be saved with a different UTC time (due to the different UTC offset) and it'll run at the correct local time of day.
• dreamcompiler 8y ago
  Obligatory Erik Naggum essay -- possibly his best ever: http://naggum.no/lugm-time.html http://naggum.no/lugm-time.html
• jugg1es 8y ago
  This article is inspirational.
• incompatible 8y ago
  "Physicists are still debating on whether or not time actually exists in the universe." I'm not aware of any physicists debating this. If time didn't exist, there wouldn't be a physical dimension for it, and everything would be at a fixed position in 3-dimensional space.
  • leni536 8y ago
    >If time didn't exist, there wouldn't be a physical dimension for it, and everything would be at a fixed position in 3-dimensional space. It's not necessarily the case. Maybe the universe is just an tangled graph of events. Maybe the dimensionality of spacetime only emerges as an asymptotic behavior of this graph and it breaks down in small scales. In this view time doesn't exist at a microscopic level.
• lopmotr 8y ago
  A tiny bit of good news recently was North Korea getting rid of their fraction-of-an-hour different time zone and harmonizing with South Korea. Sadly, Australia and New Zealand are still some of the few holdouts with stupid pointless not-on-the-hour time zones :(
• blockchain-help 8y ago
  Blockchain has shown its usefulness when recording events like transactions. This usefulness could be extended to medical records, which often suffer from inaccuracy and discrepancies. Healthcare professionals are responsible for ensuring that sensitive medical records are accurate, complete, and only available to authorized individuals. All of this can prove to be difficult when healthcare providers all have different systems for storing information. TO KNOW MORE PLEASE CHECK OUR SITE:- http://www.blockchainhelp.pro http://www.blockchainhelp.pro
• mirimir 8y ago
  > UTC isn’t directly used by people (unless they’re really weird). I find it best to stick with UTC. Otherwise there's too much ambiguity. Especially when we're all pretending to be somewhere that we're really not.
• pleasecalllater 8y ago
  Could you start making websites which are readable? Jumping icons, moving background, flickering colors, gray letters on colorful backgrounds - all that makes me hard to read... so I'm sorry, I'm not going to read that.
  • deleted 8y ago
    [deleted]
• mcauser 8y ago
  We’re going to need a new data type: spacetime
  • koliber 8y ago
    I don't know if you were trying to make a joke or not, but you are absolutely right! With space travel, both are needed to tell time. Things get even more complicated quickly. Albeit, things like 15 minute timezone offsets from UTC will become a terrestrial problem.
• basicplus2 8y ago
  Link all back to sidereal clock time...
• aiCeivi9 8y ago
  Full screen images as a lead are the most annoying thing that can happen, right? Wrong: > zachholman.com/video/utc-title.mp4
• psteinweber 8y ago
  I really enjoyed this. And I think no one mentioned the very related Computerphile video yet: "The Problem with Time & Timezones " https://www.youtube.com/watch?v=-5wpm-gesOY https://www.youtube.com/watch?v=-5wpm-gesOY Same topic, equally entertaining (not AS geeky though).
• chaz6 8y ago
  This article covers a lot of important points, but I must nitpick one in particular. GMT is not a timezone. Europe/London is a timezone. GMT is solar time which is distinct from UTC as a time system. The purpose of leap seconds is to track the difference between TAI and GMT which results in UTC (i.e. UTC = TAI + leap seconds). Since everything is relative, my preference for recording accurate historical time is microseconds since TAI0. Everything else prior and future is an estimate.
• Kognito 8y ago
  Lost me at “rich, white railroad tycoons”. What on earth does skin colour have to do with anything in this article?
• leonroy 8y ago
  One thing I’d love to know is how the heck as software devs will we manage a future moon or Martian colony with its own set of discrete time zones... Admittedly you can’t schedule a phone call or chat since the latency is too great but if you wanted to schedule an event to occur in say a software system on both planetary bodies at the same time your software or time library would need awareness of celestial mechanics...sounds like a fun problem :)
• HankB99 8y ago
  Probably not a good time to propose decitime, I guess. (No pun intended.) Day is the basic measure. Deciday = day/10. (=~ 2.4 hour) Centiday = day/100 Either could be used in place of the old fashioned hour. Milliday = day/1000 (=~ 84 seconds) Milliday seems like a good replacement for the traditional minute. Centimilliday to replace seconds? It's a but unwieldy but could be abbreviated as cmd (similar to the commonly used 'sec.') Years are a little troublesome. However with sufficient energy input a Kiloyear could be made to be 3 years. With sufficient precision (and perhaps occasional correction) it could resolve that leap year and occasional leap second issue. There would be some ramifications. For example the Newton is defined in terms of seconds so there are some units beyond pure time that would also require revision. Let's get rid of this madness of 24 hours, 60 minutes and 60 seconds. And 365.2425 days was just plain wrong from day 1.
  • dev_north_east 8y ago
    I can't tell if you're being serious...
    • HankB99 8y ago
      Only slightly. Changing the orbit of the earth to achieve a 333.333 day year is not feasible b y any foreseeable technology.
• billysielu 8y ago
  I've seen a few systems mixing up their clocks, sometimes using the database server clock, sometimes the web server clock, sometimes the user's local clock. Whatever clock you're using, be consistent about it. Users can and do configure different time zones than where they're actually located, e.g. if someone in India is working with a team in the UK, they'll probably have Indian time on their local clock, but select UK in their user profile. Also, some people travel.
• LinuxBender 8y ago
  My current time is: 1527698540 That seems easy enough for any application to deal with. Perhaps let each app or user convert that back to their ISO 8601 of preference.
• joshstrange 8y ago
  Implementing recurring events is a nightmare. Also working with potentially 4 different timezones in a single situation is terrible. We have instances where we need to display a time in a browser but we have to take into account the browser's timezone (fuck JS Date objects), the call center agent's timezone, the supervisor they are talking to's timezone, and the participant they are talking about's timezone. I hate time. I wish we would just go to a seconds-based time system ("I'll be done with this in about a kilo-second", "I work just under 28 kilo-seconds a day").
• axilmar 8y ago
  Shouldn't past datetimes be stored as nanoseconds offsets from EPOCH and future datetimes be stored as local time? In this way, we can tell the exact time something happened in the past, no matter how timezones/DST changes, but we can also have future events stored according to people's expectations.