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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..."
There is no time to worry about time.
Slow news day apparently. Plenty of time to post on /. about the meaningless.
For questions like this, my dad would always say something cheesy, like "Does it matter, son? There's no time like the present, and that's all that matters".
Of course, he didn't think going into the business world as an employee was a good professional choice, either.
- Nec Impar Pluribus, or so I'm told.
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".
.
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?
There's one standard: It's the International Standard ISO 8601
Everything other notation is to time as phrenology is to science.
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!
https://www.xkcd.com/1179/
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.
There is but one time, TAI. Everything else is just a TAI with an asterisk.
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.
I always push for the ISO 8601 time formats. I like seeing YYYY-MM-DD on my time stamps. Wish this was the industry standard for logging, file systems, etc.
What I hate how the US has Saturday/Sunday split on the weekend. Who really thinks, Oh its Sunday start of the week!
Monday is really the start of the week, right after the WEEK END, and that's how I like my calendars displayed. Monday thru Sunday.
http://en.wikipedia.org/wiki/ISO_8601
Time to make the move to fix the 2038 bug
Standards for Date/Time are one thing, I've had a lot of trouble trying to standardize on adding Dates. What's August 31st + 1 Month?
See: http://stackoverflow.com/q/7614361/37462
paul reinheimer
Jesus fucking Christ on a crackery cross, do any of you code monkeys have any idea just how many possible years today is? No, I know you don't. You know how I know this? Because you myopic fucktards have been the reason my phone has been ringing and my mail client actually crashed from overload today. So fuck you, and thank you, because I get to look super-smart and that pays the bills here in the DogPound.
Even in the fucking "Western World" we live with the Mexican stand-off of Gregorian vs. Julian calendar, and that's just the start. Entire chunks of software -- enterprise software, the shit that has to actually pass all sorts of testing -- had to be rewritten because Catholic Spain feels all butthurt if the calendar starts on Sunday. And since you're at it, well, nearly atheist yet officially religious Iceland kinda likes to have the week start on Mondays, too, and the Icelandic name for Tuesday starts with a non-ASCII character.
Today is one of around 100 different, official dates depending where you are and who you're asking.
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.
IMHO, time standards are all relative. Everything is measured relative to some celestial event: e.g., the sun rising and setting, the Earth going around the Sun, the Moon going around the Earth, the position of constellations in the sky, etc. As long as you know the origin point relative to what standard you're using and know the celestial event method used for the standard, the conversions would not be that nightmarish. Now, the degree of precision would be based on the accuracy of the origin information relative to your converted calendar and the precision of the calculation used for tracking the celestial events as originally used in the old calendar (as modern measurements of these events may introduce additional drift). So, the precision of the conversion would also be relative to the application. For accountants it would be REALLY important. For paleontologists, not so much but a little helpful.
My horror story was being handed a file from a phone system, with no documentation whatsoever, and asked to write a program to translate it so that it could be loaded into a database for reporting.
Turns out that time, durations and dates were being persisted in a binary format in the file.
It just so happened that the time tracking system was running on some form of unix running on a Motorola 68K processor. I was working on something else (probably either an HP-PA RISC or x86.
Anyway, I locked myself in a room and puzzled out the problem. I remember doing a lot of bit shifting after reading the data into memory. Once I figured out what to do, it was pretty trivial to spit out an ASCII file with dates decoded into strings.
So it really wasn't the format that was the issue, so much as the transfer of data from one machine architecture to another.
In more recent years, I recall needing to write code to validate dates (leap years, Y2K compliance, etc). I'm fairly confident that most systems have reasonable libraries to have such fun now.
I wasn't saying that I use ISO 8601. I was presenting one common standard as an exempli gratia ("e.g."), for the sake of example. I was being [slightly] pedandtic and picayune in pointing out the difference between a "time standard" vs. a "time format" which is used to encode a time+/-date value.
Jesus christ, what kind of a retard asks a basic question that can be googled?
I googled this question and found the answer in like 30 seconds, it took another 60 seconds to find 3 more sources confirming what the original told me. Thats it. Like less than 2 minutes I had 4 answers to verify eachother by from reputable sources.
Whats next slashdot going to have a headline question from a user asking how many continents are on earth? Or maybe someone will need to post on slashdot asking what 2 + 3 equals.
Google. Use it.
IMHO, time standards are all relative. Everything is measured relative to some celestial event: e.g., the sun rising and setting, the Earth going around the Sun, the Moon going around the Earth, the position of constellations in the sky, etc. As long as you know the origin point relative to what standard you're using and know the celestial event method used for the standard, the conversions would not be that nightmarish. Now, the degree of precision would be based on the accuracy of the origin information relative to your converted calendar and the precision of the calculation used for tracking the celestial events as originally used in the old calendar (as modern measurements of these events may introduce additional drift). So, the precision of the conversion would also be relative to the application. For accountants it would be REALLY important. For paleontologists, not so much but a little helpful.
ADDENDUM: The second is the only time measurement that I think is completely arbitrary. They have been trying for years to standardize it on some element's radio active property (cesium-133, I believe) to give it credibility, but as far as measurements of time go, the second is probably the most ridiculous. I still think it was invented by the Dutch East India Company (or the like), as it was most likely only useful to ship's navigators before anyone needed a time division less than an hour to do anything, or need be reminded by a bell.
I honestly think they are moaners for the sake of moaning, it's sixty minutes and it's for the vast majority of people during a two-day weekend they have off from work and other pressing engagements.
Many of them have no problem going out Friday and Saturday night till the break of dawn but those sixty minutes is going to cause them oh so much grief.
Come on, some nights there's something special on TV and you stay up for two hrs. more, other nights there's nothing happening and you turn in half an hr. early.
Or do they truly want to tell me they set the clock for bedtime just as accurate as they set their alarm in the morning?
Seven times a week at the exact same time?
"The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."
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!
There are quite a number. There are a number of completely different CATEGORIES of time formats.
For time presentation, there are analog and digital formats. Analog presentation format we are familiar with on watches and clocks is one of them. There is also an analog time presentation format where the hour hand turns once a day instead of once per 12 hours, and seemingly endless variations on these. There are time strip recording charts, timeline graphs, etc. Digital time presentation formats include your familiar hours-minutes-seconds digital clock. On scientific timekeeping equipment, we often also display numeric day of year (1 through 366). Other clocks display calendar month and date. Computer systems display it many different ways and it's often configurable.
For transmission of time codes, there are several varieties of IRIG in AM and DCLS. There is NTP and PTP (both of which comprise a transmission standard and method of synchronization), and Windows Time, which is like NTP only not as precise. There's the coding used on GPS. I don't know if GLONASS uses the same as GPS or not, but I expect they did it differently just to be different. There's the method used on LORAN... You get the picture: lots of ways of transmitting the same information -- or almost the same information. There is a variety of more precise systems used for recording and playback of signals.
And then we get to time scales. There's not just one unique answer to what time it is. The US government supports two time scales: NIST (National Institute of Standards and Technology) and USNO (United States Naval Observatory). USNO is the basis of GPS time. There are national time scales in a number of countries, notably France and each is a little different, but the national timescales talk to each other. Some timekeeping systems have leap seconds and some don't.
At a more gross level, there is the Gregorian calendar, which we use for everyday time keeping and Modified Julian Day, which is different and doesn't have any discontinuities across our current epoch. Then there are a host of ethnic and national calendars, liturgical calendars and no-longer-used calendars like the Julian calendar.
In short, too many to count.
Although this doesn't answer the article's question, I think it is relevant to the topic.
One of my peeves (that sometimes has been the cause of actual problems and misunderstandings) is the ambiguous dates that result from the American tradition of using the month,day,year order vs. most of the rest of the world's day,month,year.
Most people here would probably agree that year,month,day is the best standard because it's logical, sorts easily, and virtually no one writes year,day,month. However, the rest of the world is not logical, and people will continue to use their local standards for better or worse, even though "we" know better.
Given that, I've noticed that Americans typically separate the fields with slash "/" and everyone else with either dash "-" or dot ".". But not always. I've seen Americans use dashes (often less-educated ones, not sure why) and I've seen Europeans use slashes (though rarely).
Here is my modest proposal. Always use "/" for the American convention, and always use "-" or "." for the non-American convention. So today is 3/10/2013 or 10-3-2013 or 10.3.2013, completely unambiguously.
About as many ways you can define a string in software...
Why, because that would make sense?
Happy people make bad consumers.
You change time twice a year?
You're kidding, right? That's the funniest idea I've heard today.
You know what's even more annoying than that? People who complain about what other people want to discuss. If you don't want to discuss it, then shut the fuck up and let those who care about it discuss it to their heart's content.
We weren't even discussing DST. Just time formats and timekeeping. Is that not nerd-fodder?
Disagree. Time formats are human readable. The example you give is a time format. UNIX time (seconds since 1970) is not. It is a time representation. Which is possibly what the article is about.
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?
http://www.amazon.com/Calendrical-Calculations-Millennium-Edward-Reingold/dp/0521777526 while it doesn't necessarily answer the question posed, people interested in computing calendars shouldn't miss this book.
I have no vested interest, it's not my name on the cover ;>
Yes, what I gave is a time format. My entire second paragraph is about time formats, and I gave the example in the 2nd paragraph as an e.g. of a "time format". I was pointing out that the poster of the article seems to be confused about the difference between time standards and time formats and the interconversions and possible errors. Unix time is time readable also. it's just not as useful to most people. It's like giving someone the local temperature in "Kelvin" degrees. If it's a format which they're not used to, then they need to do mental contortions and conversions into a format/representation with which they are conversant and familiar and which has applicability and utility.
You change time twice a year?
You're kidding, right? That's the funniest idea I've heard today.
Please tell me you change your time a non-zero, odd number of times per year. Because that would be really cool . . .
I am not a crackpot.
I goofed. My code from the past two years isn't working right because of the M6000 bug -- I assumed there was no point for code to work past December 21 of last year.
I also assumed they wouldn't want their money back.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
I think the arguement in general against DST is not the time, but the change. Most people I hear complain, like myself, would like to see the time go ahead in the Spring, then scrap the whole time change crap permanently. Then call it "standard time" all year long.
My company has a timestamp class that contains 2000 lines of code.
:(
And 150 methods, some of which are duplicates, but just misspelled.
Headed over to The Daily WTF right now.
No, it's not. I'm not an American, and I loathe DST with a fiery passion.
You want to change the hours you get up and go to work? Fine, talk to your employer. Why do you have to drag my clock into it?
Still disagree. Yeah, UNIX time is human readable, but not in any practical sense. There is a real distinction between time formats and representations. Your second paragraph conflates the two.
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.
Sorry, I wrote my own in 1992. It's unintentionally similar to the ISO standard. My only goal was to make timestamps easy to sort using alphanumeric methods available to a BASIC interpreter on a barcode scanner while still being mostly human-readable .
My unintentional and unauthorized contribution to the proliferation. I assume plenty more examples also exist.
Again, sorry. At least I never submitted it to any legitimate standardization body.
I am not a crackpot.
Man with one time format knows how to tell the time. Man with two is never sure.......
And then there are people like me who would prefer the opposite ;)
Thanks, very informative. I'd mod you up if I had points!
If you like sunlight so fucking much, why don't you just move to somewhere near the equator.
Or alternate between the poles. That way you can have sunlight almost all the time.
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.
Bwahahahahaha.
Day starts at sundown.
Months are lunar and vary year to year.
Some years have more than one month with the same name. Sometimes the calendar is adjusted to account for natural events.
Sometimes extra months (leap month) are added.
There are variations on this theme as well,
Tannaitic
Amoraic
Maimonides the Mishneh Torah in the 12th century (starts the AM era)
Oh wait there is more (from Wikipedia)
There are additional rules in the Hebrew calendar to prevent certain holidays from falling on certain days of the week. (See Rosh Hashanah postponement, below.) These rules are implemented by adding an extra day to Marcheshvan (making it 30 days long) or by removing one day from Kislev (making it 29 days long). Accordingly, a common Hebrew calendar year can have a length of 353, 354 or 355 days, while a leap Hebrew calendar year can have a length of 383, 384 or 385 days
The fundamental problem is this: There are 4 naturally occurring measurements of time, all of which are in common use, and none of them are consistently expressible in terms of the other.
The 4 are:
- Years (Based on Earth's revolutions of the sun)
- Lunar months (Based on the moon's revolutions of the Earth)
- Days (Based on Earth's rotation)
- Periods of the radiation of ground state cesium 133 (which form the official SI definition of a second)
And of course you have lots of artificial units of time measurement defined or mangled from those naturally occurring 4, for convenience, with concepts dating back to the Sumerians. These were mostly created because humans have a tough time interpreting large numbers.
That's why you have at least 6 parts of an ISO-8601 date: The problem is inherently complicated, there is no easy way out.
I am officially gone from
that the Mayan calendar has expired.
As much as I like the UNIX time format, it is very limited on 32 bit systems.
I store mine in the YYYYMMDDhhmmss format. I stick to GMT/UTC for the timezone. Stor it as a CHAR(14) and you're set for another 7986 years.
The beauty of this is it fits in fixed character space, entirely numeric, is easily sortable, and easy to select by range. It is still fairly easy to manipulate, just not as easy as UNIX. It is also just as easy to break out and reformat using regex's.
Actually, the arbitrary thing above was the choice of numbers - why 24 or 60? The one earth rotation is fine, and pick the one of the equinoxes to define the day that will be used. Actually, today, given the computer based time standards, why not take it and redefine it a bit? Divvy up the day into 16 hours, divvy up the hours into 64 minutes and divvy up the minutes into 64 seconds. That simplifies the design of digital clocks, which would only need counters & shift registers to calibrate time. Of course, that simplicity ends there, since we can't redefine a year if it's based on the earth's revolution around the sun. While at this, it's a good idea to come up w/ binary based systems of measuring length and mass, as well as replacing the decimal system w/ a hexadecimal system, w/ 6 new notations on a 7-segment display to represent a-f.
Historically, a day was defined as 1 earth rotation.
And that's where you went wrong. Historically, a day was one sunrise to the next. Yeah, a celestial event. So, anything smaller than that when it was first used was arbitrary(*) and we've been trying to make them make sense since.
(*) Read this very carefully as you quoted only part of it. "Between 1000 (when al-Biruni used seconds) and 1960 the second was defined as 1/86,400 of a mean solar day". So, that means before the year 1000 the second did not exist as a defined standard; and may not have existed at all; still fuzzy on that. The minute I have not been able to dig up information on as to when it was first conceived. What you then quoted were modern (Late Common Era) definitions of what a second is, not where it came from and why it first was a "second". Their origins may not truly be that arbitrary as they did emerge from some systematic approach that required their existence, true. But why 60ths? Was a minute always that long? Time is a weird thing that we should always be asking questions about. So is "spooky" action at a distance. Effing Einstein!
I arrived in NZ to live on Oct 1, 2006. That happened to be the first Sunday in October, and according to the rules was the day that Daylight Time started in 2006. During 2007 there was rather intense lobbying to have the start date of Daylight Time be moved earlier so the extra daylight could be enjoyed sooner.
The change happened, and for 2007 the changeover date was set to be the last Sunday in September going forward. My what an outcry there was from many people protesting the awful disruption that change would cause them for days on end. Really, just bitter protests!
It turned out that the last Sunday of September in 2007 was September 30. So, compared to 2006, the change happened all of 1 day earlier. I really had to laugh at all the heat of the protests that had been put forward for really no reason. It was a hoot!
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.
Some of us like getting home from work with more free daylight to spend with the kids, excercise, do gardening or whatever.
You get home from work at the same time whether it's DST or not, so I don't understand. When it's not DST the days are longer anyway and when it is a large amount of the population that observes is in cold months so it's not like you'd get much gardening done anyway. The other examples are not daylight dependent either.
The ides of March is the 15th of March from the old Roman Calendar. The Jewish calendar is older than that, and the old Chinese calendar is older than that. The old Mayan calander told us and not the world was ending. Ancient Egypt had their own calendar, and there are two church calendars: the Julian (Eastern Orthodox) and Gregorian (Western) calendar, which is what we normally think of as the modern calendar. There is the unix standard time which is the central time standard of the internet. Microsoft has their time formats, but they were all an invention in Bill Gates' broom closet. Unix time spans the internet, because all of the networking protocols on the internet are unix protocols. Microsoft only grumpily and reluctantly adopted these formats (stolen quite liberally from bsd), after their winsock gecko proprietary crapfest protocol failed for too too many people. I also remember microsoft screwing up the internet standard NTP (network time protocol) service (everyone else's worked fine, but theirs was borked and their best advice to corporate customers was to go and get some third party software). I don't know about apples time format, but suspect things (like microsoft's) are proprietary.
Latin translation prior to Ptolemy give us the terms minute and second, as in degrees of primary minutia (minute) and secondary minutia (seconds).
Historically, a day was defined as 1 earth rotation.
And that's where you went wrong. Historically, a day was one sunrise to the next.
That doesn't make sense since humanity have been living on parts of the Earth with constant night during winter and constant day during summer since god knows when. "One sunrise to the next" doesn't make sense there. There were probably local units all over the place.
Read this very carefully as you quoted only part of it. "Between 1000 (when al-Biruni used seconds) and 1960 the second was defined as 1/86,400 of a mean solar day". So, that means before the year 1000 the second did not exist as a defined standard; and may not have existed at all; still fuzzy on that.
I have a hard time imagining all people on Earth of the 11th century all agreeing on the definition of time units at all, let alone on the second. It's probably one of those things where the now standardized time units of hours, minute and second was used more and more, and gradually took over any existing local units and standards.
But why 60ths? Was a minute always that long?
I imagine it's because it was convenient to divide the minute in the same way as the hour. There's 60 minutes in an hour thanks to the Babylonians, who used that as their base (just as we use base-10).
The minute I have not been able to dig up information on as to when it was first conceived. What you then quoted were modern (Late Common Era) definitions of what a second is, not where it came from and why it first was a "second". Their origins may not truly be that arbitrary as they did emerge from some systematic approach that required their existence, true. But why 60ths? Was a minute always that long?
IIRC "second" is short for "second minute". The same terms are also used for angular measurement with one degree being 60 minutes or 3,600 seconds. Wonder if the terms were first applied to time or angles.
...as an exempli gratia ("e.g."), id est ("i.e.") for the sake of example.
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
http://www.awaresystems.be/imaging/tiff/tifftags/privateifd/exif/datetimeoriginal.html
"For a digital still camera, this is the date and time the picture was taken or recorded. The format is "YYYY:MM:DD HH:MM:SS" with time shown in 24-hour format, and the date and time separated by one blank character (hex 20)."
Anyone who's travelled much has discovered this one - the timestamps on your camera are stuck in one timezone. No really, the standard *mandates* doing this wrong, resulting in pain and anguish for devs who have to deal with it:
http://search.cpan.org/~porridge/Image-EXIF-DateTime-Parser-1.2/lib/Image/EXIF/DateTime/Parser.pm
This date format was grandfathered into the first version of freedesktop.org's file metadata spec, but after some shouting in the feedback, it changed to using the saner ISO8601 format *with* timezone.
Too late, no one will ever see this comment, but there was a book in the late 90s called "The C Standard Date/Time Library" which talks about computer date systems and world calendar systems. One of the most interesting computer books I've ever read. If this doesn't answer your question, I don't know what would. Look for a used copy. It's long out of print, unfortunately, since it's such a good book. The publisher went kaput.
It seems that a base-10 indeed wouldn't favor so many lower digits for integer divisions. This base-60 distribution seems to have logarithmic properties, interesting..
Completely agree - I like in the summer, it not getting dark until 8 or 9 and your sun isn't coming up at 4AM, and in then in the winter setting the clocks back so that the sun comes up at about 6-7 instead of around 8. Daylight Savings Time does exactly what it says - saves LIGHT for the DAY.
Most of us have computers, phones, and atomic (ahem really radio) clocks that update themselves - all I have to do is update the old alarm clock and the clock in my car.
Most modern calendar systems (such as Exchange) take timezones and Daylight Savings Time into effect, even across areas that observe DST at different times or across areas that don't observe DST.
So seriously, what is the worst that happens? You loose an hour of sleep? Go to bed earleir! You have to set forward or back a couple of older clocks? Boohoo, that takes, how long, under a minute per clock? You are late for work on Monday? Seriously, did you not realize that everything was off an hour on Sunday (argument doesn't hold, though, if you are like me and work on Sundays)?
I think people just like to moan and complain.
As for the original post, I am getting really pissed off at Ask Slashdot topics where the person could google the answer faster than they can type up a question to slashdot.
http://lmgtfy.com/?q=how+many+time+zones+are+there
add that to
http://lmgtfy.com/?q=how+many+different+calendars+are+there
In particular, on the second link, I found this:
http://www.hermetic.ch/cal_stud/lunarcal/types.htm
Which state there are over 40 different calendars in use
So, I got 40 time zones, and 40 different calendars.
Now, if you want to get technical, instead of adding them, you would multiply the two, as each calendar could be used in any of the 40 time zones.
40*40 = 1600 POSSIBLE variations across the planet.
Seriously, people, learn how to use Google!
Why not create a news for nerds website based in your shithovel then?
I am very small, utmostly microscopic.
Ref: Carl Boyer A History of Mathematics - Chapter III. Mesopotamia 26, 2 Positional numeration.
As the Akkadians adopted the Sumerian form of writing, lexicons were
compiled giving equivalents in the two tongues, and forms of words and
numerals became less varied. Thousands of tablets from about the time of
the Hammurabi dynasty (ca. 1800-1600 B.C.) illustrate a number system that
had become well established. The decimal system, common to most civiliza-
tions, both ancient and modern, had been submerged in Mesopotamia
under a notation that made fundamental the base sixty. Much has been
written about the motives behind this change; it has been suggested that
astronomical considerations may have been instrumental or that the
sexagesimal scheme may have been the natural combination of two earlier
schemes, one decimal and the other using the base six. It appears more
likely, however, that the base sixty was consciously adopted and legalized
in the interests of metrology, for a magnitude of sixty units can be subdivided
easily into halves, thirds, fourths, fifths, sixths, tenths, twelfths, fifteenths,
twentieths, and thirtieths, thus affording ten possible subdivisions. Whatever
the origin, the sexagesimal system of numeration has enjoyed a remarkably
long life, for remnants survive, unfortunately for consistency, even to this
day in units of time and angle measure, despite the fundamentally decimal
form of our society.
No, we'll keep yelling about it and bringing it up until it changes. Too bad your job sucks and you can't vary your start time, that is not our problem. Better invest in some good outdoor lighting, DST is getting canceled sooner or later since you're in the minority, chief.
The minute was, of course, the time a chore had been done minus the time the chore was stated as going to be executed 'in a minute'.
For thousands of years then, the minute varied from 30 seconds to 60 days, but as the convention of marriage became written in stone we've seen a stern narrowing of the time window accepted to be within a minute, until the advent of the digital wristwatch which settled the matter once and for all.
Today we don't say 'in a minute' as often, but instead "I'll get right on it", "it's got full priority" and "why don't you send me an email about it?".
Defining Statistics and Social Research
"The standardization of the second took place 46 years ago."
Whoa there! You still haven't explained how we settled on the first!
Defining Statistics and Social Research
They also counted in base 60 using the knuckles of the fingers of one hand (using the thumb as a marker) and the fingers of the other hand for 5x12 counting system. There are some people who stand by this or the duodecimal system.
Google Doodle displayed amazing video to Douglas adams 61th birthday, so i want to which technology they are used to created this video.If any one knows just share it.
pedandtic
It's pedantic, as in:
1: of, relating to, or being a pedant(see pedant)
2: narrowly, stodgily, and often ostentatiously learned
3: unimaginative, pedestrian
Pedant:
2a : one who makes a show of knowledge
b : one who is unimaginative or who unduly emphasizes minutiae in the presentation or use of knowledge
c : a formalist or precisionist in teaching
This post is an example of definition 2a of pedant.
Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
What I don't like is the ridiculous way that the majority of the year is DST. DST used to be approximately half the year (end of April to end of October). It got extended for stupid, venal reasons:
* Politicians wanted to look like they were "doing something" about the energy crisis
* Certain businesses make more money during DST (basically any that sell outdoor activity gear), so they support any extension
DST should be half the year, max.
To a Lisp hacker, XML is S-expressions in drag.
For what time it was, there is really one standard. Many countries have their own time standards (like NIST and the Naval Observatory which are distributed via GPS for the US) for the current time. The have ensembles of Atomic clocks and a computer to pick an average. But these are only an estimate of official 'time'. For the real thing each contry sends their readings and correlations with the other countries to a central authority in France to decide once a month what the world wide average was.
For what time it is, my teenager runs on DST 'Dad Standard TIme'. If he's not home when the watch on my arm says so, there are consequences. The makes the answer to how many standards a few for every person on the planet. Probably more than just the humans. I'm pretty sure the rest of the fauna know's when to get up and eat.
TIme formats are another as mentioned above. There is GPS time, 1588 time, NTP time, UNIX time, Mainframe time, DOS time, etc. The above standards are often distrivuted in one of these formats with a conversion factor to seconds from some epoch.
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
There's a long human history of noon being when the sun is highest. Standard time quantizes that to time zones. I can't see any reasonable justification for trying to change thousands of years of human history, development, and expectation by making 1 PM the time the sun is highest.
"National Security is the chief cause of national insecurity." - Celine's First Law
..but that's why standards aRe so great!: there are sooo maNy of them!!!
"Daylight Savings Time does exactly what it says - saves LIGHT for the DAY."
Since DAY is when the sun is up, how does changing the way you number the hours change the amount of LIGHT in the DAY? (and do you somehow think that shouting your argument makes it true?)
"National Security is the chief cause of national insecurity." - Celine's First Law
...ask The Doctor
Oh, I'm sorry sir, I thought you were referring to me, Mr. Wensleydale.
Don't forget the Time Cube!
/ The Arrow
"How lovely you are. So lovely in my straightjacket..." - Nny
Time is relative to the observational framework. Slashdot is known for providing varying observations. Therefore time has no meaning here.
FTFY. Now back to The Nexus, I have to meet Captains Picard and Kirk for lunch.
Has anyone mentioned the HL7 Date/Time standard used to message between healthcare computing systems?
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.
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".
.
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.
Y-10K - now that's forward looking. but what about Y-100K? Or do you not think we'll be around then....SDPatricia to prove the anonymous coward wrong (but lazy me...)
In the 5th year of Obama of USA ...
You could fix that though.
http://what-if.xkcd.com/26/
360 was also a close approximation of the year (365) and quite easily divisible as well, corresponding as a close approximation for a lunar month by the divisor of 12 (12x30). Additionally, a "season" was 1/4 of the year, meaning approximately 3 months. A week was approximately 1/4 of a month (4 x 7). When you realize that we are going from "close approximation" to "highly precise" you'll realize that these things start to look silly on the micro scale we're measuring now. However, to a nomadic/agrarian society, these measurements sufficed and quite nicely, especially when you consider that these people rarely exceeded 100 travel (radius) from their homes.
I imagine that something like, "I'll meet you at that mountain, three days after the harvest full moon", was the "time keeping" of that day. It was an era of a more simple lifestyle.
Agent K: A *person* is smart. People are dumb, stupid, panicky animals, and you know it.
"Whoa there! You still haven't explained how we settled on the first!"
I don't know! (He's on third!)
Save Maine's economy: write stuff down. All comments are exclusively my own, not my employer.
Base 60 is an "ok" selection because it LCD's are 2 x 2 x 3 x 5. Which is a constuctable division of the circle. Meaning that with the primary tools of a compass and straight edge you can divide the circle into 60 equal segments. This is useful for historically accurate divisions of the sky. But the use of 360 is not. You cannot divide a circle into 360 equal parts with the above tools because it requires angle trisection. This means that our usage of 360 degrees and 360 seconds in an hour is a poor choice for accurate measurements. It is my opinion that the usage of 360 is derived in this manner:
- a circle can easily be divided into 6 parts by using the radius as a chord along the perimeter.
- the 6 segments were then divided into 60 due to the usage of base 60 in the number system.
- also: 360 may have seemed like a good idea since it is approximately equivelent to the number of days in the year. So star locations move aprox 1 degree each night
Anyhow, despite the fact that we continue to use 360 in time and angle division, it is a poor selection because it is generally impossible for any student of geometry to easily construct a 360 degree protractor using basic tools.
For the record. Any protractor that has a value of 60 times some multiple of 2 is a "good" protractor. So 120, 240 and 480 degree protractors would have been far better selections
They also counted in base 60 using the knuckles of the fingers of one hand (using the thumb as a marker) and the fingers of the other hand for 5x12 counting system. There are some people who stand by this or the duodecimal system.
I have heard of this being used to reason why there are 12 hour divisions in the day. But I am skeptical because the counting mechanism has little to do with division of time and angle of the sun.
I have come up with a different theory where the hands are used as a sundial to divide up the day. Open your hands and place them together palm up. Between the hand hold a pencil of straight stick. Position the stick so that it is directly between the creases where the thumbs separate from the palms. Now turn your hands so the shadow of the stick points to the first crease where the thumb seperates from the palm. You will see that as the sun moves through the sky, your hands will work as a sundial where creases of the thumb and fingers make for 12 divisions as the sun moves from horizon to horizon. Basically, anyone can make a sundial with their hands and a stick and it will provide for 12 divisions.
As far as the origin of base 60, I think it came from instead a division of the circle into 6 using the equilateral triangle. One of the simplest divisions of the circle beyond a simpler diameter division into 2. Each of these 6 divisions was subdivided into 60 in order to match the change in the heavens every day. Meaning that the location of a star has an aproximate change of 1 degree every night.
Bring on Star Dates
What I am trying to say is that I do not believe that our body parts were significant in the creation of time division or angle division. Instead nature was observed and used to set the stage for a meaningful counting system. The body parts were later used as a convenience for recording and remebering these values. We have a lot of things on our bodies in different numbers. The hands can be used to mimic just about any numbering system. So suggesting our hands as the reason for numbers does not provide any more reason for the usage of 60 then say using 10 or 8 or 5 or 25 or whatever combination of fingers, knucles or combination of hand signals available. For example, if the number base was 48, you could say the exact same thing and simply leave the thumb out of the equation in your counting system. ie: 12 *4 = 48
Also note. Most people will suggest base 10 comes from humans having 10 finger/digits. But this is short sighted as it has no relation to the division of circle...which is historically where all numbers come from.. ie: division of angle and time. The true origin of decimal counting (base 10) comes from the realization of dividing the circle into 10. Which requires the understanding of Phi. The proportion of Phi is required in order to divide a circle into 10 equal parts because Cos 36 = Phi/2. Which simply says that a right triangle with a height of 2 and an hypoteneus of Phi will make a 1/10th division of a full circle. Since 36 degrees = 360/10. So the logical reasoning is that decimal number systems come from triangles using Phi.
I have a hard time imagining all people on Earth of the 11th century all agreeing on the definition of time units at all, let alone on the second. It's probably one of those things where the now standardized time units of hours, minute and second was used more and more, and gradually took over any existing local units and standards.
Ancient Egypt divided daylight into 10 hours and night into 10 more. A 20 hour day was useful because they also followed a 5 day week. So the hours in a week was 100 hours. Which was useful because their number system was decimal. Long before we used it. And also, the angular divisions of hours was 1/2Phi (sin 18). So a triangle representing the shadow change of the sun in one hour was easily constructed for cultures who knew about phi.
We would probably have some sort of decimal system for both time and angle if we inherited our measurements from ancient egypt rather then babylonians. And we would probably be worshiping a sun god... which makes much more sense.
When the French concieved the metric system, they were trying to reconfigure the all measurements to be based on logic rather then history. In many ways they succeeded, but with time they failed. For a short period, France converted to metric time and the calendar was changed. However, the people did not accept and use the new system and business complained and they made changes to the calendar which made people lose faith in it. Its too bad that it didnt work. From a programming perspective metric time would be a lot easier to work with.
There are no other Slashdotters. It's all me, well, and my army of minions. I have a lot of time on my hands, and happen to be independently wealthy. I have a team of paid writers that I find in homeless shelters, who work under my direction, and we spend pretty much all of our time just filling Slashdot with junk. It's a great Silicon Valley business model if you think about it.
1. Hire homeless people to work for free. Make sure to give them superhero or scripting related pseudonyms, and take their clothing so they can't run away.
2. Fill Slashdot, and occasionally Craigslist with condescending garbage
3. Some as yet undefined step.
Go public!
Right now, we're entering our fourteenth year on the circuit, and the house I use for this has never smelled worse. That just means it's working.
Hoping to spark some VC interest later this year, as I anticipate low overhead business models, and sweatshops in general may come back into vogue.
This signature has Super Cow Powers
+1 Informative?! Congratulations. But RFC2550 is already obsolete - it depends on the Drake Equation which changed recently.
I'm in a country which very much supports it you dumb cunt.
Let's go with two: Light and Dark. The sun rises and sets every day in most places. Some places will be Light for a long time, some will be Dark for a long time, but it's either Light outside or Dark outside wherever you are...
FTFY
There are some geologists around on Slashdot who consider the 400 million year arc over which variations in the day/month and month/year ratios have been demonstrated to be a quite short time. The same effects have doubtless been going for a longer period (since the Moon-forming event), but there's around 50 million years uncertainty in that datation too.
Don't let the astronomers get started. Or the theoretical cosmologists, with their wear on the Turtle's toenails.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
There are 3600 seconds in an hour, not 360.
I sometimes ask revealing, often ignorant-seeming questions. Maybe they're harder to answer than you think.