[LEAPSECS] Consensus building?

Clive D.W. Feather clive at davros.org
Thu Feb 3 09:00:24 EST 2011

Warner Losh said:

>> SI

>> - the SI-second is a standardised unit of measurement

>> - the SI-second is currently defined as a fixed number of transitions

>> of a caesium atom

>> - the current definition of the SI-second was ratified in 1967


> Agreed. I'd also add

> - the SI-second forms the basis for many other fundamental units of measure.


>> - an SI-based-minute is formed from exactly 60 SI-seconds

>> - an SI-based-hour is formed from exactly 60 SI-based-minutes and thus

>> exactly 3600 SI-seconds

>> - an SI-based-day is formed from exactly 24 SI-based-hours and thus

>> exactly 86400 SI-seconds


> These are true only most of the time. On leap second day, they are all

> false and off by 1, typically one low. It all depends on the timescale

> that you use, and thus there can't be a universal definition here.

Actually, Stephen is right and you're wrong. The BIPM defines an SI minute,
hour, and day in exactly this form. See table 6, page 32, of:

This, of course, implies that "SI-based-" is the same as "TAI-".

Clive D.W. Feather | If you lie to the compiler,
Email: clive at davros.org | it will get its revenge.
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