discontinuity of civil time

Posted in: Tech

A discontinuity of civil time occurred this morning at midnight on New Year's Eve... But that's not the reason for the number of police out in London last night. As the clocks struck 12 (or 00) there was a leap second inserted to correct for the time getting fractionally out of step with the Earth's rotation, thus causing a momentary discontinuity. The last time this happened was seven years ago.

How this happens: the same second happens twice, represented differently,

  2005-12-31 23.59.60 <-- leap second
  2006-01-01 00.00.00

Those are both the same times (00.60 is 01.00 so 59+01 = 00.00 and so on). More technical background on the Network Time Protocol leap second page.

Unfortunately for some computers that implement the time shift by going back in time by a second (as opposed to say holding the time for that second or "slewing" [sliding]) this can cause problems. Whose idea was it to risk computer bugs on the most hungover day of the year?

PS Have a great 2006!

Posted by Paul Makepeace at January 1, 2006 14:39 | TrackBack