Slashdot Log In
Vote To Eliminate Leap Seconds
Posted by
kdawson
on Tue Nov 20, 2007 03:11 AM
from the making-y2k-look-like-a-walk-in-the-park dept.
from the making-y2k-look-like-a-walk-in-the-park dept.
Mortimer.CA writes "As discussed on Slashdot previously, there is a proposal to remove leap seconds from UTC (nee 'Greenwich' time). It will be put to a vote to ITU member states during 2008, and if 70% agree, the leap second will be eliminated by 2013. There is some debate as to whether this change is a good or bad idea. The proposal calls for a 'leap-hour' in about 600 years, which nobody seems to believe is a good idea. One philosophical point opponents make is that the 'official' time on Earth should match the time of the sun and heavens."
Related Stories
[+]
The Future of Leap Seconds 429 comments
@10u8 writes "Since 1972 precision clocks around the world have ticked using atomic seconds, but earth rotation is slowing down. Leap seconds have been inserted in order to keep noon happening at noon, but they upset some timekeepers. Recent discussions have considered
discontinuing leap seconds in UTC, and a colloquium in Torino next month will present results. It is a matter of international significance."
[+]
U.S. Moves to Kill Leap Seconds 601 comments
blacklite001 writes "Not content with merely extending Daylight Savings Time, the U.S. government now also proposes to eliminate leap seconds, according to a Wall Street Journal story. Their proposal, 'made secretly to a United Nations body,' includes adding 'a "leap hour" every 500 to 600 years.'
Hey, anyone remember the last bunch of people to mess with the calendar?"
Submission: Vote to Eliminate Leap Seconds by Anonymous Coward
[+]
US DoD Poll On Leap Seconds 314 comments
@10u8 writes "For time scales to leap, or not to leap, has been the question here before. The ITU-R will be considering leap seconds again in a few weeks. This week the USNO posted a survey about leap seconds by the US DoD. The issue has civil implications as well as technical ones, and there is a demonstrated way to respect the history, remove leaps from navigation and POSIX time, yet keep the sun overhead at noon."
This discussion has been archived.
No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Full
Abbreviated
Hidden
Loading... please wait.
Wait (Score:5, Funny)
Re:Wait (Score:4, Funny)
Parent
Re:Wait (Score:4, Funny)
Parent
year 2612 bug anyone? (Score:4, Insightful)
We can ignore the problem then too. Eventually, morning and evening will be on different days. We might just gain or lose a whole day. Heck, we can ignore the problem forever. We'll be off by a year, then a decade...
Re:year 2612 bug anyone? (Score:5, Funny)
Parent
Re:year 2612 bug anyone? (Score:5, Funny)
Parent
Re:year 2612 bug anyone? (Score:5, Funny)
Parent
Re:year 2612 bug anyone? (Score:4, Insightful)
Basically, you compute what time of day it is based on your clock ticks and the orbit and spin of your planet. You don't need to model the entire orbital mechanics of your planet... if you think about it that's what all "time of day" systems do now... highly simplified models of the Earth in space. We know that the earth will be inside the zone of space we call "November" and we know it will be turned to the position we call 6am UTC when the clock ticks out this number or any number in this modulo. As we become more demanding of time and more exacting of the position of the planet in space we need to make more sophisticated orbital models... or allow for heuristic adjustments to existing look up table based models.
Time as in time-space has nothing to do with any of this and it is passage of time in space that a computer should be worried about keeping inside itself... not where the sun is. If you want "where is the sun?" you should be use a conversion or algorithm to calculate "where is the sun?" and the "time" inside the computer should be seen as the number of clock cycles that computer has experienced. Using clock ticks alone, your computer can probably do a fair job at guessing at where the sun is... but that's not what computer time is about.
Of course, these ideas neglect relativity. Eventually we'll have to deal with relativity and clock ticks. I suppose you would have to decide on an a set of arbitrary points in the cosmos and call their inertial frame of references "fixed" which you would use to compute temporal differentials via a kind of relativistic triangulation... say clocks in three star systems that transmit their time beats out to the universe and based on the time you read from each at your point in space you can triangulate your position and time-shift due to relativistic effects. But I think I may be getting a few centuries ahead of myself.
And, it doesn't matter what I think anyway. It's not like anybody in a position to influence these decisions and ideas reads Slashdot. If you started now you could probably get all the digital clocks in the world to work on these principles in about a hundred years.
Parent
Chrono-noobs! (Score:5, Funny)
Why not just make each second a little longer? (Score:5, Interesting)
Re:Why not just make each second a little longer? (Score:5, Informative)
Originally, back in the 1960's, instead of the leap seconds, they (the BIH at the time) adjusted the rate of the UTC seconds with respect to TAI. This was widely viewed as not a good thing once it was tried and was dropped, IIRC in 1972.
Parent
Re:Why not just make each second a little longer? (Score:4, Insightful)
If nothing else, we'd stimulate the living hell out of the world's economy.
This is the broken window fallacy [wikipedia.org], nothing more.
Besides, the value of units of measurement lies in their consistency. Changing the second is worse than leap years or leap seconds or leap hours, because any time someone needs a precise measurement, they turn to the second.
Parent
Re:Don't have to. (Score:5, Informative)
Parent
Other way (Score:5, Interesting)
Re:Other way (Score:5, Interesting)
How about going the other way... leap microseconds. Many times during the day. Then nobody will hardly notice.
Actually it sounds like a good idea. As someone else suggested, the difference due to leap seconds is so small that only atomic clocks are precise enough to need to take them into account. And since we're all synced on atomic clocks anyways we could just make that happen transparently upstream.
Parent
What would be wrong with (Score:5, Interesting)
One event every 10 years does not cause lots of disruption, and being a minute out of sync with solar time is not large enough to be a problem. You'd notice an hour's difference if you're in a northerly latitude and have Daylight Saving Time...
Re:What would be wrong with (Score:5, Informative)
Worse, different systems have different implementations. There's bsd, sysv and vixie's implementations, plus numerous variations, and all seem to do their own stuff.
An example: You have four boxes located in the
Which of the three jobs will run on each box on March 30, 2008?
Which of the three jobs will run on each box on October 26, 2008?
Which of the three jobs will run twice on October 26, 2008?
If anyone (except perhaps Arthur D. Olson) can answer that without investigating, I'd be very surprised.
Sometimes the vendors themselves can't say for sure, due to the time adjustment occurring in a different process, and depending on availability of interrupts and CPU time on the system, the cron interrupt may see either the old time or the new time when it wakes. One of the above vendors thus recommends that jobs scheduled for the start/end of the witching hour are moved one minute outside it.
Anyhow, the parent to your post deserves to have the "+1 Informative" stripped, because it's plain misinformation.
Regards,
--
*Art
Parent
This is why... (Score:5, Funny)
A 'leap-hour' in about 600 years (Score:5, Insightful)
Please take some care with editing... (Score:5, Insightful)
Um... isn't the whole point of this article that some people think it's a good idea? TFS even says there is debate over whether it is a good or bad idea!
600 years? Who will remember? (Score:4, Funny)
What a number of people don't realize... (Score:5, Interesting)
Changing the length of the second simply won't work, in a couple of hundred years we'll be right back to where we started again. See http://en.wikipedia.org/wiki/Leap_second [wikipedia.org] for details.
The leap hour is a daft idea, why change something that isn't broken, if a tad inconvenient.
If it ain't broke... (Score:3, Insightful)
This is a bad idea, and my understanding is that it has not much chance of being adopted.
Leap hour ... WHY? (Score:3, Interesting)
How about DST (Score:5, Insightful)
The only benefits I can see is slightly later barbecues in summer and a six-monthly reminder to check smoke detector batteries about the house.
Re:How about DST (Score:5, Interesting)
BTW: I'm of the opinion that it's not DST that should be abolished, but non-DST. Non-DST time is a good mathematical division of the day, centred equally around 12:00 (+- 30mins). Unfortunately, as a society, we seem to have decided to centre our actual lives around 13:00 instead. Switching permanently to DST would fix this.
Parent
Re:How about DST (Score:4, Interesting)
You might think of the "9-5" workday when saying that the center is 13:00.
But in reality, its more like 15:00 (most people wont be a lot of time awake _before_ going to work, but lots of time after...
Parent
This is a modern problem (Score:3, Interesting)
Steer the Earth (Score:4, Funny)
Re:Steer the Earth (Score:5, Insightful)
We could just fire off some nukes every six months or year to control the orbital speed of the earth around the sun.
Congratulations, you completely failed to understand the fundamental difference between a day and a year! A feat accomplished by few to this day!
What defines the day is the rotation speed of the Earth around itself, not the orbital speed around the Sun. Besides, as some other people pointed out, this whole leap second thing is irregular, or if you prefer, one step forward, one step back, because the speed of rotation of the Earth varies slightly.
Parent
Simple and accurate solution (Score:5, Insightful)
UTC = TAI - leapseconds
Then define all the timezones off of UTC as normal. All this basically does, is make the calculations for the timezones into a few hours plus or minus a few seconds. This makes a lot more sense, because then you actually have a fundamental time (TAI) which doesn't have discontinuities, but if you want to consider your astronomical orientation, you look at UTC or your local time. We don't need to redefine these types of time, because these already exist. We just need to use them more intelligently.
Change time (Score:4, Funny)
Come on it's been nearly 2008 years since we had BC, it's time for a change !
Synchronize your watches? (Score:4, Insightful)
Corollary... (Score:4, Interesting)
Having our clocks NOT agreeing with astronomical time, completely eliminates all the benefits of time zones.
Whether you actively think about it or not, our sense of direction is substantially driven by the combination of our clocks, and the Sun. We use it as a reference all the time (why do you think it's harder to find your way in a new area, when it's dark?). Even if there's no other defining features, there's still the Sun to tell us which way is North (or South), and our clocks give us a reference to relatively where the Sun should be. Subtly change someone's clocks, and you'll see them having a slightly more difficultly with their (otherwise good) sense of direction.
Seems to me, the only argument here is that there are a few groups who _really_ just happen to need TAI time, but they see that it's just much easier to access sources of UTC time, and so want to redefine UTC (eliminating leap seconds) so that it is monotonic, and strictly corresponds with TAI at all times. Did I miss anything?
The problem isn't leap seconds (Score:4, Insightful)
Many electric grids are required to be timed with accuracy of better than 10 milliseconds. Remote Telemetry Units need to record events with a time stamp that might mean something to an operations control center. The problem is what do you do with leap seconds?
The POSIX standard time epoch doesn't include leap seconds. So you're left with a terrible morass of a problem. Do you do what the NTP deamon does, by slewing the clock at some known rate? The problem with that is that while events remain in sequence, the time between events is not accurate. Do you simply include a second 59th second? The problem there is that events will be recorded out of order and they can't be sorted back.
And yet, many also have legal requirements to adhere to a UTC based time standard.
Ladies and Gentlemen, the problem isn't the leap-second concept. The problem is our damnable entrenched software standards. We're trying to fix this problem by creating another.
Seems Easy Enough to Solve (Score:5, Insightful)
For UT1, eliminate the concept of hours, days, etc. Time will be told by the second only. Maybe even call it something else like a "chron". You can talk about hectochrons, millichrons, kilochrons, etc. In fact, start the counting of "chrons" at January 1, 1970.
Now, if you use chrons, there is no more link between days or years, and no more leap seconds. Computer systems like GPS or space travel which get thrown off by leap seconds, but don't really depend upon the concept of "day" or "year", can use chrons. People who depend upon the astronomical time can use seconds and live with leap seconds. To each, their own. And, converting between the two units is quite really simple.
The real silliness of the whole proposal is that these scientists actually think their decision will eliminate the leap second. Astronomers will simply ignore the whole thing and go back to GMT. So will all the governments which means all the atomic clocks will still use leap seconds. UTC will simply disappear, and we're back to square one.
Re:Metric time? (Score:5, Interesting)
Decimal time always reminds me of the scene in Metropolis with two clocks on the office wall [wikipedia.org] -- a 24-hour clock and a 10-hour clock (the length of the workers' shifts).
Parent
Re:Metric time? (Score:4, Insightful)
Chinese didn't "invent" decimal time. Phrases like "in the 1/10000 th part of a chand" and words like paramchand (not accurate transliteration; chand = second) etc., are very common in Sanskrit text. Add the fact that Decimal system itself was invented in India only means that Decimal time was "invented" in India.
Why I am using double-quotes for "invented"? Because no one can invent time. As a human you want to divide time to keep track of it. And you can only do that using the numeral system you know! Indians knew decimal system so they divided it into factors of 10, Sumerians used sexagesimal system, so they divided it into 60.
It is not the division that bears any importance in invention. It is the device which one can use to measure. If you don't have clocks to measure 1/10000 th part of second, it means nothing to write it down. Ancient Chinese are no different.
Parent
Your post - Bollocks (Score:5, Informative)
There were 240 pence to the old (pre-decimalisation) pound, comprised of 20 shillings each worth 12 (old) pence. Do you remember guineas, crowns, half-crowns, shillings, tanners (6-penny piece), threepenny bit, pennies, half-pennies, farthings (a quarter penny)? I do. I suspect that I am quite a bit older than you and I cannot ever remember there being 120 pence to the pound. So either please provide a citation or confess that you are mistaken/talking bollocks. :-)
But the main thrust of your post was correct with regards to dividing sums of money easily. Or at least it was until the education system decided that mathematics and mental arithmetic were not the most important subjects in life. I'm not sure how some of today's young people could cope with such problems.
Parent
Re:Your post - Bollocks (Score:4, Interesting)
From the article..There are two people, Tina Farrel and a sales assistant that need to be darwinised.
Parent
Re:Your post - Bollocks (Score:5, Interesting)
Personally, I think the people who judge other people fit to be "darwinised" - especially based on a page-long Web article - are the ones we could do without, rather than the people who's worst known flaw is that they can't count below zero.
Parent
Some numbers... (Score:5, Funny)
That would be an interesting transition period as people got used to indicating or recognizing the numbers 4 or 128...
Parent
Re:Some numbers... (Score:5, Funny)
Take one hundred
Binary add thirty two
Fingers say fuck you
Parent
Re:Some numbers... (Score:4, Insightful)
Parent
Re:Metric time? (Score:5, Funny)
Parent
Re:Metric time? (Score:5, Funny)
Parent
Re:Yup. (Score:5, Insightful)
What is a year?
Is it the time from perihelion to the next perihelion?
Is it the time from zenith on the shortest day to zenith on the shortest day next year?
Is it the time for when a star within our galaxy is in the same position again?
Is it the time for when a star outside our galaxy is in the same position again?
The earth's orbit rotates, and the solar system rotates, in a galaxy that rotates. And speculation is that the universe rotates too.
Parent
Re:Yup. (Score:5, Funny)
Parent
Re:Metric time? (Score:5, Funny)
The smallest unit is the "Moment", and then the "While" (or, less used, the "Whilst"). A while is about 14.4 moments. Then you have the "long while", which is 13.8 whiles, then the "time", and "long time"...
For example, it took me a while and three moments to write this comment. I'm not a quick typer...
Parent
Re:They have to add a leap something, sometime (Score:5, Informative)
Parent