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Announcements Science

Leap Second This Year 107

Posted by timothy from the seconds-all-taste-the-same dept.
ygslash writes "The IERS has announced today that, after seven years, there will once again be a leap second this year. On December 31, 2005, the time 12:59 will last for 61 seconds."
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Leap Second This Year More

Leap Second This Year

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  • Oh the opportunity! (Score:4, Funny)

    by SDMX ( 668380 ) on Monday July 04, 2005 @09:00PM (#12982273)
    What AM I going to do with all that extra time?
  • you really think we'll still be using this system of time when leap seconds add up to a significant amount?

    • Re:Should we really bother? (Score:5, Interesting)

      by B.D.Mills ( 18626 ) on Monday July 04, 2005 @09:31PM (#12982368)
      It depends on your definition of "significant".

      I have calculated[1] that in 1000 years a leap second will be required about every two months. It's likely that at that time we would still be using time standards similar to those in use now.

      On the other hand, in 1 million years, about 15 leap seconds will be required each day. Therefore, at some point timekeeping must necessarily divide the day into units that are not an integral number of seconds. We would have a situation where the record for the 100 metres dash is expressed in seconds, but the length of the second used for dividing up the day is not the same length. Such "stretched time" has already been used for the Spirit and Opportunity rovers on Mars.

      [1] A common formula for approximating the evolution of delta-T over time is 31 * Cy^2, where Cy is expressed in centuries.
      • Not so many centuries ago, the concept of 'hour' was flexible, depending on the season. 12 day hours, 12 night hours, regardless of the ratio between them. Back to the old?
      • I expect that as the concept of the "year" becomes more and more antiquated and less and less meaningful, we will begin to simply count some arbitrary number and due without the likening to arbitrary phenomena.

        You dont think things will change in 1000 years? It's hard to keep things the same for 10.
        And that will just get more tedious once we abandon the "year", of course. ;)
      • I have calculated[1] that in 1000 years a leap second will be required about every two months. It's likely that at that time we would still be using time standards similar to those in use now.

        Simple solution, change the 60 Hz power line frequency to 59.9999885922 Hz, causing power-line synchronous clocks to slow down to match the daily rotation of the Earth (as referenced to the Sun).

        On the other hand, in 1 million years, about 15 leap seconds will be required each day.

        Simple solution, change the 59.9
        • Adjusting the AC Frequency is not a viable option. The Hertz value already fluctuates with load.

          It's very close to the engineered value (50 or 60) but is constantly fluctuating.

          That is why AC powered clocks that use the HZ to drive them tend to need adjustment over time.

      • A common formula for approximating the evolution of delta-T over time is 31 * Cy^2, where Cy is expressed in centuries.

        The formulae are to some extent empirical as well as being approximations. The evolution of delta-t is also extremely 'noisy', and is far from a good fit with any of the formulae [phys.uu.nl].

        For the last few years it's been at around 64 seconds (see data in here [navy.mil]), which comes to about 3 or 4 seconds less for the present time than some recent formulae were predicting even only a few years ago, and l
        • It's a bit optimistic to extrapolate over 1000 years!

          This is why I made sure to state that the formula was an approximation.

          Although it is unlikely that such formulae are going to be accurate 1 million years form now, it does not detract from the point that I raise, namely that our current definition of 86400 seconds to the day and 1 second = 9192631770 cesium transitions cannot both last indefinitely.

          Will there be six leap seconds in 3000? Unlikely. But suppose you owned a very accurate wrist watch and
          • In a million years people might start adjusting the orbital speed of the earth to fix this. Or they might redefine the second to be a few more cesium transitions.

            Personally I think it's a little far off to guess what we are going to be doing.
      • I have calculated[1] that in 1000 years a leap second will be required about every two months. It's likely that at that time we would still be using time standards similar to those in use now.

        You're off by a bit, and are making some invalid assumptions to start with.

        Steve Allen of the Lick Observatory has a great paper explaining the the fundamental clock problem [ucolick.org] and also exploring effects and impacts on society. It's really quite fascinating, and considerably more complex than most people imagine. I'v

    • Yes (Score:1)

      by jpardey ( 569633 )
      You forgot to take into account "Double Leap Seconds"

      I remeber reading about some Unix library or whatnot (ctime or something) that could handle them... musta been a slow news day on /.

  • Star Trek has it figured out. (Score:4, Funny)

    by Goalie_Ca ( 584234 ) on Monday July 04, 2005 @09:11PM (#12982303)
    Stardates [wikipedia.org]
    The only problem is that no one knows how its supposed to work.

    • Re:Star Trek has it figured out. (Score:5, Interesting)

      by toddbu ( 748790 ) on Monday July 04, 2005 @09:46PM (#12982419)
      The only problem is that no one knows how its supposed to work.

      They work much like warp speed - start out low and end high. The higher the epsiode number, the higher the range. I think that it's derived from fishing, where "the big one that got away" gets bigger each time the story is told.

    • The other problem is that if starship travel at warp speeds, you run into problems with relativity, unless everyone uses one central clock. And if warp speed is >= (c) speed of light, then you're completely screwed.
      • Theoretically, warp speeds are always > c; and they are free of relativistic effects.
      • Actually, and it's been a long time for me here, but I think Warp 1 = speed of light and the other warps went up from that exponentially. So warp 9.9 wasn't 9.9 times faster than the speed of light. It was many many many times greater than that...which is how they were able to zip around from one end of the quadrant to the other in a manner of days.

        And of course, they explained away relativity effects because they were in a "warp bubble" when at warp speed...that is if they weren't trapped on the Holodeck

        • From the Star Trek Encyclopedia:

          • Warp Speed Chart for Starship Enterprise, NCC-1701D
          • Warp Factor 1: 1c
          • Warp Factor 2: 10c
          • Warp Factor 3: 39c
          • Warp Factor 4: 102c
          • Warp Factor 5: 214c
            Note: New Cruising Speed
          • Warp Factor 6: 392c
            Note: Old Cruising Speed
          • Warp Factor 7: 656c
          • Warp Factor 8: 1,024c
          • Warp Factor 9: 1,516c
          • Warp Factor 9.2: 1,649c
            Note: Old Normal Maximum Speed
          • Warp Factor 9.6: 1,909c
            Maximum rated Speed, can be maintained for 12 hours
          • Warp Factor 9.9: 3,053c
            Auto-shutdown of engines after 1

          • Note: Under the old system (used in the Original Series,) devised by Zephram Cochrane, the speed at any warp factor was given as: Ship's Velocity diveded by C is equal to the Warp Factor Cubed.

            Therefore, in the Original Series, a Warp Factor of 3 was 27 times the speed of light, while a Warp Factor of 14 ws 2744 times the speed of light, or between Warp 9.6 and 9.9. I do not have the forumala for determining Warp Factors for the system, nor for the new system above 9. (They are the same formula, though

          • I think warp 10 can be reached by Douglas Adams' improbability drive. Or some other device that can be everywhere at the same time... I can't remember exactly, but it seems i can remember reading a story about something like this.

            • Yes, the nice thing about the Improbability Drive is that the ship occupies all points in space at the same time, and then appears in the place you want to be.

              Generally speaking, that is.

  • Shouldn't the time be 12:01? If the first second of 1/1/06 is going to be doubled, like TFA says...

  • Yay! (Score:3, Funny)

    by kyle90 ( 827345 ) <kyle90@gmail.com> on Monday July 04, 2005 @09:30PM (#12982363) Homepage Journal
    I've always wanted a timeslip (i.e. from the Mars Trilogy)
  • I don't care. I have an atomic watch that will automatically adjust. It is solar powered too, so I never have to worry about the bateries running down either. I love my watch.

  • Its always bugged me how... (Score:3, Interesting)

    by IronMagnus ( 777535 ) on Monday July 04, 2005 @09:43PM (#12982405)
    Its always bugged me how in a leap year, we have an extra day... but a leap second is an entire extra second... if the terminology were consistent, that would mean a leap yer would equal one extra year.. or that a leap second was some fraction of a second longer than a normal one.
  • From the IERS website:
    Welcome to the International Earth Rotation and Reference Systems Service

    Will they change my oil and check my brakes, too?

  • I knew it! (Score:3, Funny)

    by purpleplatyduck ( 896319 ) on Monday July 04, 2005 @10:12PM (#12982524)
    "To authorities responsible for the measurement and distribution of time..." How do I make an official complaint with these time-distributing authorities for all the times I've been blamed for being late? Everyone always thought it was my fault for running out of time--but nope, turns out there are "authorities" in charge of all that. Are they any relation to the Tooth Fairy?

  • Two questions (Score:3, Insightful)

    by roystgnr ( 4015 ) <roy&stogners,org> on Monday July 04, 2005 @10:19PM (#12982549) Homepage
    Isn't this sort of thing calculable farther in advance? There shouldn't be a whole lot of angular momentum being added or subtracted from the Earth's rotation.

    Do I need a new glibc? Or any other POSIX library, for that matter? If this is a new announcement then presumably every implementation of mktime(), localtime(), gmtime(), etc. needs to be updated.

    • Re:Two questions (Score:3, Insightful)

      by lachlan76 ( 770870 )
      Actually you'd just set the NTP server you're syncing with one second ahead. I don't think that a once-every-seven-year event is going to be worthy of kernel changes, especially since your time is probably off by more than one second as it is.

      • Actually you'd just set the NTP server you're syncing with one second ahead.

        That simple solution will cause one of two problems: either your time will be off by one second, or the calculation of the number of seconds between two events crossing the leap second will be off by one second.

        I don't think that a once-every-seven-year event is going to be worthy of kernel changes, especially since your time is probably off by more than one second as it is.

        If you're regularly using NTPD your time is probably

        • If you're regularly using NTPD your time is probably not off by more than one second, and if you've got a GPS receiver it almost certainly isn't. But I agree with you that a kernel change isn't necessary, in fact, the kernel shouldn't be involved with terrestial time at all.

          PC hardware sucks, or just mine. I sync ntpd every 4 hours on my workstation which is on all the time, consistantly it needs to adjust it by "0.31xxx" seconds. And that's just for four hours, imagine running it only once per day or on
          • Sounds like a software issue, not a hardware one. If your clock consistently needs to be adjusted by 0.31xxx seconds, then ntpd should be automatically adjusting by 0.31 seconds every 4 hours. ntpd will do this if it is run in daemon mode.

    • Re:Two questions (Score:5, Informative)

      by Mudd Guy ( 716972 ) on Monday July 04, 2005 @11:19PM (#12982769)

      Actually, it's not calculable farther in advance. The Earth's rotation is inconsistent enough that leap seconds are sometimes needed, but the need can't be predicted more than about a year in advance [1]. In other words, there is noise in the Earth's rotation period of about 1 second per year. Atomic clocks are a lot better than this (good to ~50 ns per year [2]!!!), so it's pretty easy to detect the problem.

      Sorry, I can't help with the second question.

      [1] See this Wikipedia article [wikipedia.org].

      [2] See this Wikipedia figure [wikipedia.org].

    • This change totally screws up my New Year's Plans! Blast you, leap second! Blast you!

    • According to a link I just read, POSIX doesn't handle leap seconds [cr.yp.to]. So yes, if you use NTP, like someone else suggested, your time will be correct, but any measurements of time crossing leap seconds won't.

      The correct solution in my opinion would be to store leap seconds along with the timezone information. That's really what they are. Unix time could be stored in TAI instead of UTC, and thus subtracting two times from each other would still give the correct result.

      Whenever a leap second was announced y

    • Well, regarding the second point, think of this as a reminder of why you should NEVER EVER store future time and date values as offsets from an epoch time/date, if being one second off is bad for your application.

  • Off by one error (Score:4, Interesting)

    by Taral ( 16888 ) * on Monday July 04, 2005 @10:19PM (#12982551) Homepage
    Oh, joy. Everyone'll be off a second on the damn New Year's count... again!

  • Ugh! (Score:2, Funny)

    by poena.dare ( 306891 )
    This year's been bad enough for me, now it seems like it's going to drag on forever!

  • 12:59 AM or PM? (Score:3, Informative)

    by nicholaides ( 459516 ) <mike.nicholaidesNO@SPAMgmail.com> on Monday July 04, 2005 @10:55PM (#12982680) Homepage
    Actually, if they RTFA it's 11:59 PM... just wanted to clarify.

  • leapsecond.com (Score:4, Informative)

    by antispam_ben ( 591349 ) on Monday July 04, 2005 @11:24PM (#12982786) Journal
    I just wanted to be the first to mention this site, someone wanted to view the previous leap second, and that became an obsession.

    Okay, here's a clickable link:
    http://leapsecond.com/ [leapsecond.com]

    An obsession in another are of time is this Y10K Compliant clock:

    http://longnow.org/ [longnow.org]
  • IIRC, time is a key element of GPS accuracy.
    Even if updates come from atomic clocks, a human will have to key in a correction to a significant number of servers.
    Maybe Murphy and Chicken Little will show up for our New Years party.
    • GPS uses it's own time scale, which has a fixed offset to TAI (TAI - 19 seconds). There are no leap seconds in the GPS time scale.
      • Interesting.
        So we have "time in a bottle", so to speak.

        Lets look at how time has progressed:

        CT based on UTC by the ICWM at the 10th GCWM
        ES based on NTS ratified at the 11th, GCWM
        SI equals ES from USNO and NPL discovery as ratified at the 13th GCWM
        UT1 monitored by SRSPEOP of the IERS, thus we get LS adjustments according to CCIR.

        Now we get TAI by BIPM expressed as UTC+dAT
        GPS is sychronized to UTC but not adjusted with LSs

        OK, hold onto your pants...
        Until 1960, UT independant of AE.
        UT then replaced by ET.
        E

  • 58 (Score:1, Redundant)

    by eingram ( 633624 )
    Why can't 12:58 be 61 seconds long? Or perhaps shorten :57 by 10 seconds and just make :58 71 seconds long!
  • The last time I listened to WWV [slashdot.org] (the shortwave broadcast of NIST time), the signal said we were -0.6s ahead of time (ahead of the Earth's rotation). My thinking is that if we put in a leapsecond now, then we'd be -1.6s ahead - am I missing the point of the time broadcast code, or is this a hoax?

  • Bad for Microsoft (Score:4, Funny)

    by anthony_dipierro ( 543308 ) on Tuesday July 05, 2005 @09:35AM (#12984660) Journal
    Microsoft has $33.8 billion in short term investments. Since interest payments are calculated by the day, and not the second, at an interest rate of 3% Microsoft will lose $1929 in interest due to this leap second.
  • 12:59 on Dec. 31st is the only time in the whole year that people are paying attention to the seconds. Why not choose some other time when it's not going to screw up my countdown?
  • Shouldn't the summary read 11:59pm aka 23:59?

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