Vote To Eliminate Leap Seconds 531
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."
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...
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!
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.
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.
Re:Why not just make each second a little longer? (Score:2, Insightful)
I am not an expert, but the "exact second" calculation you want to make, averaged over a long enough period of time, seems to me to depend on the motions of every sizeable object in the Solar System and probably also (or maybe even more strongly) on fluid dynamics within the Earth's core. Both of these systems are almost certainly chaotic ones, and therefore probably not amenable to the solution you suggest (pre-calculation).
Don't have to. (Score:2, Insightful)
One second in 600 years is about 1/18921600000 or roughly 0.000000005%. In a day, the difference between the two ways will produce an offset of 1/220000th of a second, or about 5 nanoseconds. With the possible exception of atomic clocks, no analog or digital device is this precise.
Since any "precise" timekeeping requires periodical synchronization with the world's atomic clocks and astronomical observatories, we'd only need to change them, and the rest will just pick up the new info. Any "standalone" device that does not rely on the above synchronization has a much bigger margin of error than this change would introduce, so they will not be affected.
Yes, you can argue that in 60 years a machine not running the updated time would be 1/10th of a second behind a machine that does and in a deeply hypothetical scenario it could possibly cause some problems, but if the machine is not synchronizing to begin with, its own imperfections will result in a much larger discrepancy than 1/10th of a second in 60 years caused by the time change.
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.
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.
Re:Metric time? (Score:1, Insightful)
Hey, wait - seconds are base 60? What kind of bizarrity is this? I demand the ITU create a new, proper measurement of time, with proper decimalization! 24 hours in a day? Good Lord man, you must be joking. And a calendar system so broken that it has leap years EVERY FOUR YEARS? Sounds like the ITU took the coward's way out, and simply adopted an old imperial system, gave it a coat of paint, and called it "metric". A system that uses base 60, base 24, base 7, and can't even decide between base 30 and 31, not to mention the "month" is based on something so profoundly un-metric as the PHASE OF THE MOON?
While you are at it: "Down with DST!" (Score:3, Insightful)
Synchronize your watches? (Score:4, Insightful)
Re:Why not just make each second a little longer? (Score:3, Insightful)
You would need to make the second variable length since the leap second is inserted at variable intervals to compensate for the non-constant slowing of the Earth's rotation.
Re:A 'leap-hour' in about 600 years (Score:3, Insightful)
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.
Re:Unix epoch and leap seconds (Score:3, Insightful)
Since when has "ample warning" helped? <points at Y2K and the IPv4 address shortage>
No, everyone leaves these problems until the last minute and then runs around trying to prevent the sky from falling in, even if they are known about years in advance.
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.
Re:What a number of people don't realize... (Score:3, Insightful)
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.
And while you're at it... (Score:1, Insightful)
Leap Seconds Ruin My Day (Score:3, Insightful)
Re:How about DST (Score:3, Insightful)
Until our society decided to center our lives around 14:00.
For the past couple summers, I've been protesting DST by simply not changing any of my clocks. It takes a bit to get used to, but once you learn to translate times, it works out. And as someone who doesn't mind getting up earlier in the morning (though I do like to sleep in when possible), it does help you realize how you are making better use of your day.
But the number one thing I realized during my experiment is that DST by itself does nothing. The twice a year change is what makes it work. DST is really a trick (or a conspiracy, for the paranoid) to get people who would just as well sleep in to get up a little earlier. For some reason it was easier to get everyone to change their clocks than to convince everyone to start work an hour earlier. Maybe it's psychological -- getting up at 5 AM seems like a lot earlier than getting up at 6 AM. And going to be between 9 and 10 PM seems like a lot earlier than an adult should be going to bed.
As much as I think DST is an abomination, it probably can't go away. People simply don't know how or won't want to adapt to getting up earlier by themselves.
Who here thinks its a good idea? (Score:2, Insightful)
Legacy systems which need absolute time now and use UTC
Legacy systems which need something resembling mean solar time now
Why change it instead of making a new standard for new systems which need absolute time? It breaks nothing and accomplishes the same goal. I fail to see the logic in the present change, except for the fact that it will make some people a lot of money since huge amounts of systems will have to upgrade from UTC to whatever new standard emerges to take it place for use by most of us.
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.
Re:Some numbers... (Score:4, Insightful)
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.
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.
Wrong question (Score:3, Insightful)
That length was divided into 24 hours, each of which was subdivided into 60 minutes, then 60 seconds, and the exact time represented by a second was fixed. Then we found out that the length of a day is getting just a teeny bit longer, and the accumulated error amounts to a second over the course of a year or more. Or maybe the original measurements were off by that much.
Whenever the astronomers determine that things are far enough out of whack, they declare a Leap Second to try to keep the average time of noon the same. They either add a 23:59:60 right before midnight on the last day of a quarter (so far only Dec 31 or Jun 30 have had this honor), or theoretically could omit 23:59:59 (but this has yet to happen).
Otherwise, 12:00Z will no longer be mean astronomical noon at the Greenwich Observatory, which is pretty much the point of having a Prime Meridian in the first place.
Re:Please take some care with editing... (Score:3, Insightful)
I suspect the people who think dispensing with leap seconds et al are people who don't care about the underlying astronomy that goes into how we calculate time.
If you don't update your time to match how the actual configurations of orbits and the like works, then your equinoxes, solstices and other fun stuff stop lining up.
Carried on long enough, Spring would happen in fall, but it would take while.
People tend to forget there's a real, underlying physical system which we have to make our reckoning of time match up to. It's not quite as arbitrary as people think. Our current mechanism of measuring time is based on centuries (actually, millennium) of measuring time and the orbits and the like that go into it.
Leap seconds are just way of keeping it in sync.
PI can't be made to be 3 either. =)
Cheers