[LEAPSECS] ISO Influence

Rob Seaman seaman at noao.edu
Sun Dec 19 12:47:50 EST 2010

On Dec 19, 2010, at 10:16 AM, Joe Gwinn wrote:

> There is a deep difference here:


> In Y2K, there was going to be a discontinuity, the first occurrence of a "20xx" date in a computer world that had only known "19xx" dates.


> By contrast, in the proposal to drop leap seconds, the periodic discontinuities would cease.

There is another deep difference. Y2K remediation involved no re-imagining of our underlying concepts of calendar dates and clock times. The ITU, on the other hand, is attempting to legislate reality. Civil timekeeping is (and will remain) time-of-day. The ITU just wants UTC to lie about it. The question is whether the tolerances underlying that lie rise to an actionable level.

...in addition leap seconds don't just cease - rather, DUT1-style corrections will assume a growing importance. Currently DUT1 is negligible for many purposes - this won't remain the case.

Leap seconds exist in service of mean solar time (sidereal time adjusted to lap the Sun once annually). Omit leap seconds and the clock rate diverges from the natural rate.

Discontinuities do not just cease - rather, contingent issues will pop up elsewhere. Any proposal to redefine UTC should address those issues.


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