[LEAPSECS] The definition of a day

Steve Allen sla at ucolick.org
Thu Jan 29 10:03:27 EST 2015

On Thu 2015-01-29T13:25:02 +0000, Peter Vince hath writ:
>      There have been some strong views expressed that a "day" has to mean a
> solar day, i.e. midnight-to-midnight (or midday-to-midday).

A basic component of the dispute is "The time that people have agreed
upon."  Leap seconds persist now because they are written into the
document which is recognized as the standing agreement, and that
agreement incorporated the then existing agreement about a day while
changing the agreement about a second.  It's really weird for UTC
to be the only time scale where the duration of one day is unrelated
to the duration of one second, but that is the agreement.

Many who dislike the implications are already ignoring strict
conformance with the agreement, namely IEEE 1588, ITU-T Recommendation
G.8265.1, GPS, Advanced Television Standards Committee, Galileo, the
system clock inside Android devices with GPS, BeiDou, IRNSS.
Their systems work without leaps yet the sky has not fallen because of
their failure to conform.

> What HAS affected me is the
> disruption caused by, and please forgive the loose phraseology, the adding
> of an extra second every now and then.

The documents presented to the assembly of the ITU-R have not
contained detailed descriptions of the success of systems that have
avoided being affected by leap seconds.  They have also not contained
detailed descriptions of the failures of sytems that have been
affected by leap seconds and an explanation for why those failed
systems were unable to adopt the strategies of the successful systems.

Many of the delegates to the ITU-R represent nations where the civil
calendar is strictly determined by the observation of the moon.  The
documents presented to the assembly of the ITU-R have also not
mentioned how the option of abandoning leap seconds affects the
definition of the day.

I haven't seen how the delegates can make an informed decision to
forge a new agreement when they have inputs that do not contain
analysis of of important technical, legal, and cultural aspects.

Steve Allen                 <sla at ucolick.org>                WGS-84 (GPS)
UCO/Lick Observatory--ISB   Natural Sciences II, Room 165    Lat  +36.99855
1156 High Street            Voice: +1 831 459 3046           Lng -122.06015
Santa Cruz, CA 95064        http://www.ucolick.org/~sla/     Hgt +250 m

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