Slashdot Mirror

← Back to Stories (view on slashdot.org)

Leap Second At The End of 2005

Posted by CmdrTaco on from the correct-your-watches-immediately dept.

Ruff_ilb writes "Because of the discrepency between an ephemeris second (the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time) and the second of atomic time (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), we're left with more than leap years. In order to ensure that the the atomic time and civil stay coordinated, "Civil time is occasionally adjusted by one second increments to ensure that the difference between a uniform time scale defined by atomic clocks does not differ from the Earth's rotational time by more than 0.9 seconds."" And Happy New Years everyone ;)

19 of 269 comments (clear)

  1. How did you use yours? by Chemisor · · Score: 4, Funny

    And, of course, I already used it to read Slashdot. Oh, darn...

    1. Re:How did you use yours? by Extrudedaluminiu · · Score: 5, Interesting

      Do any NTP servers keep track of these seconds?

      --
      -vs, me@acm.jhu.edu
    2. Re:How did you use yours? by tonsofpcs · · Score: 4, Informative

      Most NTP servers use UTC time, so yes.

      http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat - leap second bulletin

      --
      Video Production Support
    3. Re:How did you use yours? by lousyd · · Score: 4, Insightful
      Do any NTP servers keep track of these seconds?

      Yes, that's the point of serving the Network Time Protocol...

      --
      If aspiration is a virtue, achievement cannot be a vice.
  2. A cool thing to do by rolypolyman · · Score: 5, Funny

    If you watch carefully for that leap second, you can do a freeze-frame flying kick like in The Matrix.

  3. The hard way by Anonymous Coward · · Score: 5, Funny

    Adjusting the clock is of course the easy way to solve the mismatch between our ideal time and earth's rotation.

    Real engineering solution would involve changing earth's rotation speed to match the clock. Any takers?

    1. Re:The hard way by MyLongNickName · · Score: 5, Funny

      Adjusting the clock is of course the easy way to solve the mismatch between our ideal time and earth's rotation

      Oh yeah? It took me about ten minutes to adjust all the clocks in my house due to the damn leap second. Multiply this by the 100 million households in the nation, and we have a very serious issue here.

      I demand that George Bush pull us out of whatever God forsaken U.N. treaty that got us into this mess.

      --
      See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
  4. Highlights problem with ntp... by Dr.+Zowie · · Score: 4, Informative
    The NTP protocol that all of us cool kids use to synchronize our computers' clocks has a fundamental flaw -- the NTP time is tied to UTC, but contains no leap seconds at all, more like TAI, the atomic time standard. When there's a leap second, the system's solution is to ignore it.

    So, as of today, any time stamp you have made using NTP, ever, has been retroactively displaced by one second. Intervals that included midnight (UTC) last night are all too short by one second.

    This may not be a problem for handling your calendar appointments, but it can muck up all kinds of scientific applications that require high precision.

    1. Re:Highlights problem with ntp... by thehickcoder · · Score: 5, Insightful

      Actually, if you where doing high precision scientific applications, it seems this type of behavior would be preferred. Because of the leap second there was not 2 seconds between 11:59:59 and 12:00:01 last night. So, using the NTP behavior if I want a timestamp that was exactly 10000000 seconds ago, I get one that represents 10000000 actually elapsed seconds.

      Just because everybody agrees to change their clocks doesn't mean time actually slows down or speeds up.

    2. Re:Highlights problem with ntp... by Dr.+Zowie · · Score: 4, Interesting

      Hmmm... Maybe I wasn't clear to start with. If (using my handy atomic clock) I made an NTP timestamp at precisely 11:00 pm UTC yesterday, and another NTP timestamp at precisely 11:00 pm UTC today, those two timestamps would differ by exactly 24 hours, although the two UTC times are 24 hours and one second apart. That is an error. T

      he error is carried by the fact that NTP stays synchronized to UTC in the present, but the past is "free floating". If, today, I convert my previous NTP timestamp back to UTC I will find that it occurred at 11:00:01pm yesterday rather than 11:00:00, the time that I actually made it. That's because NTP counts offsets from the present moment, assuming that UTC behaves like TAI.

  5. Re:happy new year by SpinJaunt · · Score: 4, Funny

    More along the lines of 730 days if you include the dupes..

    --
    /. is good for you.
  6. time.gov by srblackbird · · Score: 5, Informative

    I watched the time at Time.gov: 23:59:56 (UTC) =>23:59:57=>23:59:58=>23:59:59=>23:59:60!=>00:00:0 0
    It was Amazing! This was the first time for me... *remebers where I was at that moment

    --
    "The test of the morality of a society is what it does for it's children." -Dietrich Bonhoeffer
    1. Re:time.gov by Rytsarsky · · Score: 4, Informative

      Screenshot: http://flickr.com/photos/jk3us/79978824/

      --
      God became man to enable men to become sons of God. -C.S. Lewis
  7. old news by Viriatus · · Score: 5, Funny

    Old news, from last year.

  8. It's not the 'ephemeris second' that's the problem by Jonathan+McDowell · · Score: 5, Informative

    Original poster is slightly wrong - it's not the length of the 1900 ephemeris second,
    it's the fact that the Earth, like all of us, is getting older and slowing down, so that
    the 2005 "Earth rotation" second (i.e. 1/86400 of one spin of the Earth) is longer than
    the 1900 equivalent and longer than the atomic time (SI) second. Instead of changing
    the length of the second, it is currently deemed less painful to keep using the old
    length and stick in an extra second every now and again.

    Since this depends on the slop of the Earth's interior, it's not a fully regular and predictable thing - we might even have to remove a second one year.

  9. Great by the+eric+conspiracy · · Score: 4, Funny

    Gotta love those long weekends!

  10. Leap Second Lovers Are Traitors Says Bill O'Reilly by Fishstick · · Score: 4, Funny

    "This year's leap second is an assault on the American public," says commentator Bill O'Reilly. "The reason the leap second is even being proposed is because of America Haters, because of Iraqi hate mongers, and let's be honest, Shiites. Why would you add a second to the year unless you're an anti-American hate monger?
    I remember liberals at a party saying, 'let's add a second to the year' and I was the only one who spoke up against it. Why would they want to add a second to the year? Because it gives them a second longer to hate Bush.

    "Look, look, look, look. A leap second is a denial of everything American, of everything good, of everything moral. They're saying we need this second because the earth rotates on its axis and revolves around the earth, well this is the no spin zone. So we don't need a leap second. Though I would rather have a leap second than some of these hate-mongers who go around hating even their own ideas! They need to hate their own ideas so much that you have many liberals proposing the leap second, which is an idea that they hate, yet, they propose.

    "I am so so so so upset with these people, who actually believe their ideas, yet, I have no hate in my heart. I am a simple guy, who only has my own true beliefs and a few products that are my cornerstone to fight against the leap second poobah. Let me say it aloud: Leap Second, leap second, leap second. Doesn't it sound ugly?

    "Please, don't let these Darwinian leap-seconders, who believe that the planets revolve around the sun, who believe that rocks are sedimentary, igneous and stalactites, who are innocent dim-wit believers in a faith bordering on hating everything religious like trees and fruitcake, yet, who don't believe in John 7:12:45:67:89, have their say.

    "But you know what I love? Dialogue. Rational dialogue which allows me to say that aliens from a Iraqi loving planet want to abolish Christmas by adding a leap second to the Darwinian anti-God year. Dialogue is what keeps the American system God-loving and anti non-God. It also keeps the anti-God loving non-Iraqi loving insurgent deniers able to voice their hideous so-called opinions over the American loving tolerant airways. And now let's take some calls."

    Steve Martin

    --

    There is much cruelty in the universe, John.
    Yeah, we seem to have the tour map.

  11. Log of Atomic GPS Clock adjustment by BiggRanger · · Score: 5, Interesting

    I did up a project on sourceforge.net a few years back to sync my computers with a GPS http://atomicgpsclock.sourceforge.net/. Below is a log of the activity, normally there is a +/- 0.016 or so second instability, but 18:59:59 EST (or 23:59:59 UTC) the Navy made a 1 second adjustment to the GPS system, and it's vibible in the log at the next scheduled sync (in bold)

    2005.12.31 18:33:49 00032 GPS Status - Tracking: 3D
    2005.12.31 18:43:27 00020 Offset: 000.016 Buffer: 13
    2005.12.31 18:43:27 00032 GPS Status - Tracking: 3D
    2005.12.31 18:43:49 00020 Offset: -000.031 Buffer: 13
    2005.12.31 18:43:49 00032 GPS Status - Tracking: 3D
    2005.12.31 18:45:15 00033 GPS Status - Tracking: No
    2005.12.31 18:45:34 00032 GPS Status - Tracking: 1D
    2005.12.31 18:46:48 00033 GPS Status - Tracking: No
    2005.12.31 18:46:52 00032 GPS Status - Tracking: 3D
    2005.12.31 19:01:43 00033 GPS Status - Tracking: No
    2005.12.31 19:01:55 00032 GPS Status - Tracking: 1D
    2005.12.31 19:03:45 00020 Offset: 001.016 Buffer: 13
    2005.12.31 19:03:45 00032 GPS Status - Tracking: 2D
    2005.12.31 19:13:45 00020 Offset: -000.016 Buffer: 13
    2005.12.31 19:13:45 00032 GPS Status - Tracking: 3D
    2005.12.31 19:23:43 00020 Offset: 000.000 Buffer: 13
    2005.12.31 19:23:43 00032 GPS Status - Tracking: 3D
    2005.12.31 19:33:43 00020 Offset: 000.000 Buffer: 13
    2005.12.31 19:33:43 00032 GPS Status - Tracking: 3D
    2005.12.31 19:43:30 00033 GPS Status - Tracking: No
    2005.12.31 19:43:40 00032 GPS Status - Tracking: 1D
    2005.12.31 19:53:41 00020 Offset: -000.031 Buffer: 13
    2005.12.31 19:53:41 00032 GPS Status - Tracking: 3D
    2005.12.31 20:03:39 00020 Offset: 000.000 Buffer: 13
    2005.12.31 20:03:39 00032 GPS Status - Tracking: 3D

  12. Re:Typo by eobanb · · Score: 4, Funny

    Double "the" in article:

    In order to ensure that the the atomic time ...

    No, that's a leap the.

    --

    Take off every sig. For great justice.