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Ask Slashdot: How Many Time Standards Are There?
jjoelc writes "Being one of those 'suffering' through the time change last night, the optimist in me reminded me that it could be much worse. That's when I started wondering how many different time/date standards there really are. Wikipedia is a good starting point, but is sorely lacking in the various formats used by e.g. Unix, Windows, TRS-80, etc. And that is without even getting into the various calendars that have been in and out of use throughout the ages. So how about it? How many different time/date 'standards' can we come up with? I'm betting there are more than a few horror stories of having to translate between them..."
IMHO, Time Standards would be "standards/standardizations for time keeping", such as say when the railroads crossed the US and decided that local high-noon was not so useful when you translate yourself geographically so swiftly, and thus "time zones" in the US were set up. Some countries (India, and China, maybe others i don't know of...) keep a signle time zone for the entirety of their contiguous expanse for "standardization".
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Time Formats, again IMHO, would be the "standard" (ha, I heard it [that word] both ways!) used for displaying, communicating, or storing "time data values" on paper, verbally, or in a computerized (or book-keeping) record. One example: "yYYYY-MM-DD-HH-mm-ss.{fractional value of second}" [note I added an extra "y" digit to allow for the Y-10K problem!!!). Floppy disks and TRS-DOS and Apple DOS and MS-DOS and CPM and UNIX and so many others use different formats for this. They also use different "loci" for the "origin point" of time (the "epoch", e.g. time elapsed since point $x$ in time. Gregorian year 1904 for old macs, 1970 for the unix epoch, etc.
1. How many different date/time standards has the human race come up with
2. How many different data structures and APIs have tech companies invented in trying to model the present-day Gregorian calendar (with time zones and DST, etc) used by most Western countries?
It's anyone's guess which one would produce a higher number.
It was absolutely awful trying to convert between the game-time and real-time.
I took the easy route and still based everything on seconds, and built it up from there.
The main reason for doing it was because the game was based on real time, so even being away caused events to pass.
And given a typical person, they'd play games more or less at the same time every day for a certain period of time.
This is why I settled on what would effectively be 7 hour days.
Out of sync with a normal day so a typical person would almost certainly come across every time period at some point.
And 7 is short enough to experience in a day, but still long enough to feel "right".
I can't remember how I done minutes or hours again, it was way back in 2005.
That project never got completed due to health reasons.
I might come back to it one day, but it isn't a priority.
At least I never decided to make a language for it as well.
Isn't that somewhat close to ISO 8601? I generally find it good and sensihle, helps with sorting and reading.
Why UNIX?
on a side note, i love this website:
http://www.merlyn.demon.co.uk/critdate.htm
it is a huge list of important dates relevant to computer programs, algorithms, and O/Ses.
https://www.accountkiller.com/removal-requested
There are in total 863 different time standard, including historical ones. That's the good thing about standards, there are so many to choose from.
Now, please someone post a link to that xkcd comic and we can move on to the next question.
My first program:
Hell Segmentation fault
Excel is known for considering year 1900 as a leap year even though it's not, but I don't know if this historical bug (carried over from Lotus 1-2-3 according to wikipedia) is still respected. So consider Excel usable to year 1901 to a date I don't know.
Likewise the Y2K38 problem with Unix is that time, if represented with 32 bits, doesn't go before a certain 20th century date as well as ending abruptingly on a certain date and time in 2038 - causing the end of the world. Both examples mean that you have to pay attention to the usable time range - be it usable length, absolute minimum date, absolute maximum date, with hopefully some time standards offering infinite range (like A.D. / C.E. year numbering?)
Leap seconds is another infuriating problem and relativity in general and I have to wonder if we have to consider Mars's time, Earth's time, Sun's time, Voyager 2's time etc. in any relevant way. Have fun!
Another interesting one is GPS-Time, which is basically UTC without the leap seconds.
https://en.wikipedia.org/wiki/GPS_time#Timekeeping
http://xkcd.com/1179/
This subject has already been discussed.
However this particular topic has me wishing I could moderate the actual news posts themselves.
We get it, Americans don't like DST - good for you, please stop posting hundreds of goddamned articles on it.
Some of us like getting home from work with more free daylight to spend with the kids, excercise, do gardening or whatever. No, we can't change the time we start work, no we're NOT going to see business's move to an 8-4 model.
My only complaint is it's not an all round time thing, if society isn't going to move to the 8-4 model then damnit just change the zones forward.
Furthermore I've been told by several American pals in the last 2 or 3 days, they actually like DST, they dislike when it's not DST infact and it's just common misuse of the term, don't know if this is true or not.
In conclusion, just deal with it and for fucks sake stop posting these articles every year.
You could've saved some time just saying you use ISO 8601...
Worse than suffering through the actual daylight/standard time changeovers, are dealing with timezones themselves in code. Most timezones are full hour offsets from UTC, but there are a few that are N:30 or N:45. There are even offsets which are greater than 12.
Then you have to deal with differing dates of when the changeovers actually happen over the years in a given timezone.
If you ever write an iCal-related application and have to deal with recurring events, you'll soon realize that Outlook's iCal support is comparatively even worse than IE's web standards support.
Also, relevant xkcd.
We have quite a lot of them, but we don't have many systems that are fully RFC2550 Compliant:
https://tools.ietf.org/html/rfc2550
Things you think are in the Constitution, but are not.
This is what happens when you don't.
http://infiniteundo.com/post/25509354022/more-falsehoods-programmers-believe-about-time-wisdom
Wow, sent an e-mail as suggested when clicking on "use classic" banner, and got a fast response that addressed my msg
Swatch Internet Time is truly the savior to all of this trouble. http://en.wikipedia.org/wiki/Swatch_Internet_Time
The whole time zone thing is just ridiculous in this age of information. When I'm too busy cruising the information super highway, I don't want to worry about whether the person I'm on IRC with is in London or Sydney. And for that matter, seconds? minutes? Relics of the past. Just divide the day into 1,000 beats and you're good to go.
So what if no one has any sense of what 10 beats is (14 minutes 4 seconds), and so what if it was created by a watch maker probably to sell more watches. Swatch Internet Time is the wave of the future, man! Throw your grandfather clocks away and dial-up to greatness on your 56k. You don't want to be left behind in the Swatch revolution!
Cute joke, but I recall having a realtime manufacturing BI system that was programmed so all production at two sites would come to a halt if any node computer was more than 30 seconds off-time from the rest.
Took a hell of an NTP architecture, which is what I would answer TFA submitter with: NTP is nearly universal platform/OS-wise, and it saves you from having to worry about whatever standard a given computing device uses.
Even Windows (which has a pretty crap set-up IMHO) can be tweaked to behave time-wise with the right registry settings.
Quo usque tandem abutere, Nimbus, patientia nostra?
Not sure if this is what the OP is looking for, but my favorite is the Ethiopian calendar (no, I'm not Ethiopian). It's about seven years behind us, which meant that they avoided the Y2K catastrophe until 2007.
Oh, there wasn't any catastrophe?
The length of day is not stable
http://www.nasa.gov/topics/earth/features/japanquake/earth20110314.html
Over the long (looooooong) term days are getting longer
http://en.wikipedia.org/wiki/Day_length#Historical_variation_of_day_length_because_of_tidal_acceleration
Dude, how on earth can you get it all so badly wrong? Is this a subtle postmodernist troll or something? Sorry if it isn't, starting a discussion on a scientific subject with "IMHO" sets off my bullshit alarm.
Historically, a day was defined as 1 earth rotation. An hour was 1/24th of a day, a minute as 1/60th of an hour, and a second as 1/60th of a minute. Hardly very arbitrary, is it? Problem is, turns out that there are constant fluctuations and drift on the length of a celestial day (and year). This is very impractical because there are no known clock mechanisms (bar the solar system itself) that can catch these fluctuations, so humanity needed a more solid definition of time for entirely irrelevant tasks such as performing precise scientific measurements and keeping GPS sattellites in sync. Common off-the-shelf clock mechanisms couldn't be used for this purpose because they also fluctuate too much. Instead, we redefined the lenght of a second based on an immutable physical property: the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. Cesium was "arbitrarily" chosen because of atomic clock engineering and accuracy considerations, the hyperfine transition was "arbitrarily" chosen because it is not too easy to skew, directly relates to a physical constant and can be measured in a reasonably convenient way, and the number 9,192,631,770 was "arbitrarily" chosen to make the SI second as close as possible to the then-best estimate of the average duration of the celestial second (1/86400 of a day). Then we redefined the SI minute, hour, day,... based on that physically immutable(*) second. Problem is, that didn't stop the earth rotation and solar system from fluctuating. And that's why we have leap seconds now and then; to keep our non-arbitrary SI-based time in sync with the arbitrary vagaries(+) of the solar system.
(*) Well, pretty immutable for the practical applications you're going to care about. There's always room for improvement.
(+) To be precise, orbital mechanics are well-understood so in that sense they're not random.(#) Problem is, it's a chaotic system, so no matter how precise we measure all the boundary conditions, a simulation of the solar system will over time deviate more and more from reality. That's why leap seconds are based om measurements.
(#) If you look even deeper into the subject, there are solar winds and weather-dependent tidal effects contaminating the whole shebang with fluctuations we can't even predict a few weeks in advance because they're complex. So yeah, arbitrary.
The standardization of the second took place 46 years ago. It is now the basis of SI, the international system of standards. The following is from NIST, the Federal Government agency in charge of standards:
"The unit of time, the second, was defined originally as the fraction 1/86 400 of the mean solar day. The exact definition of "mean solar day" was left to astronomical theories. However, measurement showed that irregularities in the rotation of the Earth could not be taken into account by the theory and have the effect that this definition does not allow the required accuracy to be achieved. ... Experimental work had, however, already shown that an atomic standard of time-interval, based on a transition between two energy levels of an atom or a molecule, could be realized and reproduced much more precisely. Considering that a very precise definition of the unit of time is indispensable for the International System, the 13th CGPM (1967) decided to replace the definition of the second by the following ...:
"The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."
Not only that but, length is now defined in terms of the second:
"In turn, to further reduce the uncertainty, in 1983 the CGPM replaced this latter definition by the following definition:
"The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.
"Note that the effect of this definition is to fix the speed of light in vacuum at exactly 299 792 458 mÂs-1. The original international prototype of the meter, which was sanctioned by the 1st CGPM in 1889, is still kept at the BIPM under the conditions specified in 1889."
In the land of the blind, the one-eyed man is king.
24 and 60 were not arbitrary. They were chosen by ancient Babylonians because they are cleanly divisible by many numbers; 24 by 2, 3, 4, 6, 8, and 12, and 60 by 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30. It was important to be able to divide time cleanly because they didn't have fractions or decimals at the time. Citation needed, of course, but I don't have time to find a source and this is something I remember from when I was a kid.
I sometimes ask revealing, often ignorant-seeming questions. Maybe they're harder to answer than you think.
Isn't that somewhat close to ISO 8601? I generally find it good and sensihle, helps with sorting and reading.
However it is a bit short-termist. I prefer RFC2550 as a long-term solution
what days mark the ends of the week?
The problem with you line of thought is that the weekend is singular, not plural.
Except a week has two ends and they fall at the ends of the week
It's always been "the weekend". Singular, not plural.
Sunday being the first day of the week and Saturday the last according to the Greco-Roman tradition
No. The Romans had the concept of Saturday and Sunday being the weekend. Not Sunday being the start of the week.
The whole concept of a week having an end, rather than it's reality as being a continuous cycle, comes from the bible, where The sabbath was the 7th day. So Saturday being the end of the week is a Jewish tradition, and Sunday being the end of the week is a christian one.
In things that have a natural direction, start comes before end. Sunday is part of the weekend, therefore the week started the previous Monday. So long as "weekend" is singular, the implication is that Monday is the start of the week.
I'm British. We most commonly do dd/mm/yy. with a small minority of people doing dd-mm-yy.
The French also use dd/mm/yy. Not sure about the rest of Europe.
So your proposal won't work.
Much fun can be had by convincing a Solaris machine that the date is in the 1800s since it appears that dynamic libraries don't work then due to a bug in the dynamic linker. I'm guessing that bug will show up sometime in the future too. The interesting part is there doesn't appear to be a way to put the kernel into the 1800s via any standard API. The FORTH boot loader can be told to play games with the hardware clocks on some machines which can then be used to simulate these time travelling machines.
1) so we all know and love the modern US and European way of calendar generation. 24 hours in a day, 365 +1 on leap year this is called the Gregorian Calendar.
Well It took me by shock when I learned of the other different calendars when trying to create an international holiday calendar that correctly identified holidays that closed the trading markets. So here is a short summary.
2) Julian time is the integer assigned to a whole solar day in the Julian day count starting from noon Greenwich Mean Time, with Julian day number 0 assigned to the day starting at noon on January 1, 4713 BC. (copied from wikipedia) this is used by Astronomers ALOT. And serves as a basis for translating between different calendar systems.
3) The Chinese calendar is a lunisolar calendar, incorporating elements of a lunar calendar with those of a solar calendar. ( from wikipedia ) So basically the days are subject to the sun rising and setting just like the Gregorian calendar.. But the months are tied to the winter equinox. So the winter equinox MUST always fall within a certain month and then the rest of the calendar is built backwards, with a set number of days each, and sometimes you need an extra month to accommodate. It works and is very complex. If you own the book Astronomical Algorithms and know programming you will have enough information to create a calendar as accurate as the Chinese produce.
4) The Hebrew or Jewish calendar ( , ha'luach ha'ivri) is a lunisolar calendar used today predominantly for Jewish religious observances.(taken from wikipedia). The current year of the Jewish calendar (16 September 2012 to 4 September 2013) is AM 5773. The Jewish day is of no fixed length. The Jewish day is modeled on the reference to "...there was evening and there was morning..." in the Creation account in the first chapter of Genesis. The really interesting thing I learned is that every hour is divided into 1080 halakim or parts. A part is 3 seconds or 1/18 minute. This makes predicting the moon extremely accurate to estimation. Also a Metonic cycle equates to 235 lunar months in each 19-year cycle. This gives an average of 6939 days, 16 hours, and 595 parts for each cycle. But due to the Rosh Hashanah postponement rules (preceding section) a cycle of 19 Jewish years can be either 6939, 6940, 6941, or 6942 days in duration. But this calendar is extremely easy to program.
5) Arabic calendar. I never could figure out this calendar system. It is similar to the Jewish calendar but where one allows months to move progressively throughout the year the other is fixed so that months happen around the same time every year. I forget which one does which. Sorry, it been a while. This calendar is supposed to be very computer friendly as well, however I could not figure it out within the time frames of the project I was doing.
6) The Hindi calendar is to my knowledge one of the most complex and complex, and complex ... did I mention complex calenders in existence. I never figured it all out. But it has to do with a month starting depending on where the moon is when the sun rises on a given day. It can be figured out, but because it is based on very complex dimensions like sunrise which varies based on location, and perceived placement of the moon, which varies by location, the calender is fractured into different version for different regions. I am sure it is a good calendar, I just don;t understand how it fits in a 21st century setting. Basically if you have to deal with someone using a Hindu calendar or need to write a contract and guarantee payments that you will get, base it on days, not months or years. Trust me you will save you and your organization brutal misunderstandings. Everyone agrees a day consists of nighttime and daytime.
Those are the 6 calendars I dealt with. They represent the calendars in use by the biggest economies in the world. But there are more. What I learned that impressed me the most was that all of them outside of the Gregorian and Julian are anci
The Mayan calendar doesn't end just because one cycle (and not even the longest cycle) in their calendar system ended. Its like saying that Gregorian calendar ended just because we reached the end of a month (say, August), even though the Gregorian calendar has longer cycles than months (e.g., years), and doesn't have any particular end-of-world prophecy associated with the end of the cycle at issue.
The whole "end of the world" thing was a New Age myth inspired in part by Mayan legends about the end of an previous creation and the expiration of a particular cycle, not a Mayan belief.
the real problem with time is that it is a highly subjective measurement.
Lunchtime, doubly so!
"For every expert, there is an equal and opposite expert"
You could fix that though.
http://what-if.xkcd.com/26/
Where "the right registry settings" means turn off Micor$haft's BS "Windows Time" service and install an actual NTPd. (WT will only keep a sane time in a domain.) I've been doing that since Window 95! (anyone remember "Tardis"?)