7 ms·

I love this kind of stuff. For example the date of October 6th, 1582 doesn't exist. https://blog.yossarian.net/2015/06/09/Dates-That-Dont-Exist https://blog.yo

• lohfu 6y ago
  in most countries the dates 6th - 14th october 1582 existed since far from all countries switched to the Gregorian calendar when the Papal bull to switch was issued. Essentially only Catholic countries followed the bulla. Russia, for example, didnt switch from the Julian calendar until 1917.
  • dahart 6y ago
    That’s pretty interesting. So is Ruby’s behavior - calling the date invalid - is that bad behavior, or a totally reasonable choice to assume the DateTime is Gregorian? It would be neat if the exception said why the date was invalid, but I guess for any dates going back in history globally we should try to use a more sophisticated time lib that takes calendar and locale into account whenever they exist.
    • tangus 6y ago
      It's documented. >A Date object can be created with an optional argument, the day of calendar reform as a Julian day number, which should be 2298874 to 2426355 or negative/positive infinity. The default value is Date::ITALY (2299161=1582-10-15).
    • jcranmer 6y ago
      The Gregorian calendar was adopted in arguably four main spurts. The first spurt changed over in 1582, and was exclusively Catholic countries. Most of Protestant Europe then changed in 1700, in a second spurt. The third spurt was the Anglosphere, switching in 1752, and Sweden, switching for good in 1753. The final spurt was Orthodox countries changing over during and after World War I. There is an additional wrinkle to comment on, which is that not every country started their year on January 1. And when a country changed their year start to January 1 is often not the same as when they changed from Julian to Gregorian. In the absence of more specific information, it is usual to assume that an unlabeled calendar reference is a Julian date reference (starting on January 1) until October 4, 1582 and a Gregorian date reference from October 15, 1582 onwards, with October 5-14, 1582 not existing. It should be noted that this calendar does not correspond to any actual calendar used by any polity in actual history that I am aware of, but it would tend to be less confusing than actual historical calendars.
      • rmah 6y ago
        What about non-european cultures? When was the Gregorian calendar adopted generally in india, central asia, the far east (china, japan, korea), south-east asia, east africa, west africa?
        • jcranmer 6y ago
          East Asia adopted the Gregorian calendar as part of the drives to Westernization: Japan in 1873, Korea in 1895, and China in the early 20th century (post-Qing China wasn't a unified country following the same rules). In the Americas, the Julian or Gregorian calendar would have been adopted at time of European conquest. Similarly, in most of the rest of the world (which was conquered by Europeans at some time or another), civil administration would have switched to Gregorian when Europeans started administration, although this might not imply a change in local usage of calendar. Islamic countries have had the most resistance to the Gregorian calendar, with Saudi Arabia not using it (de jure, although it was used in private industry de facto) until 2016 and Iran and Afghanistan still not using it.
          • mehrzad 6y ago
            Iran uses its own observation-based solar calendar (which means it follows the seasons exactly every year), but it also reports the Gregorian date on the nightly news. People in Iran are generally aware of the Gregorian month and year they are in, if not the exact date.
        • deleted 6y ago
          [deleted]
• esrauch 6y ago
  I would have presumed the perceived gap was "yesterday we were using Julian, today we'll use Gregorian" (or Gregorian v0 to v1). Instead the article suggests it is "before today Julian and Gregorian both existed and were the same, now Gregorian has jumped".
• elliekelly 6y ago
  Time is one of those weird things I didn’t give much thought to until I started programming. And in the beginning it annoyed me that something as “simple” as time could be so complicated for computers. But then I read stories like this and I try to imagine how we’d deal with these complexities if they hadn’t been fixed before things got so complicated. What would happen if we told the world in 2020 that we’re just going to skip ten days ahead on the calendar? How many things would break? I suspect a whole lot.
  • bartvk 6y ago
    Yup, me too. I thought I figured it out, until I started builing apps for an airline. Cabin crew wish to view their schedules in local times when departing and arriving. It took several tries to show their schedule in a calendar-like view that intuitively made sense to them.
    • lisper 6y ago
      It's not just airline crews. I do a lot of traveling, and I want to enter my itinerary in my calendar in terms of the local time where I will be at the time of the event. I use a Mac, and Mac calendar assumes that all times are local to the time zone I'm in when I entered the event. So when I'm on the road, I would like to change the time zone on my laptop to match the local time where I am, but I can't because if I do, Calendar will move every event on my calendar to a new (wrong) time. So I have to keep my Mac's time zone set to my home time zone in order to not have it screw up my calendar. It drive me nuts.
• rkagerer 6y ago
  Samoa is near the international date line and flipped back and forth a couple times to align with whoever it was doing more trading with at the time (Asia or US). In 1892 they celebrated 4th of July (US independence day) twice.