[LEAPSECS] WP7A status and Re: clinical evidence about time and sun

Rob Seaman seaman at noao.edu
Thu Dec 18 16:23:57 EST 2008

On Dec 18, 2008, at 9:15 AM, John Cowan wrote:

> The median number of changes over the century-give-or-take of standard

> time (exactly when standard time begins depends on the jurisdiction)

> is 3, minimum 1, maximum 17 (!), mean 3.94, standard deviation 2.88.

> Even if we ignore all changes before the Unix epoch, we still have 545

> changes in 231 jurisdictions.

And how precisely is this making your point? In the absence of a
coherent zoneinfo scheme like Steve Allen's, you are asserting that
the (literally) rock solid basis of mean solar time anchored deep in
the Earth, be replaced with a completely unreliable mapping that
varies under diverse authority both in geographic location and by
decade and century. Historians and scientists interested not only in
marking time - but in doing something useful with it - will mock this

Again - civil time is clearly a flavor of mean solar time, whether or
not we decide to cheat by embargoing leap seconds or by sloshing the
timezones around. For example, we have sent missions to Mars, and the
obvious and immediate response of the projects operating equipment on
the surface was to establish a mission clock synchronized to Martian
mean solar time.

There are two types of time - interval and Earth orientation. Civil
time clearly has more to do with the latter than the former.
Technological systems often (but not always) rely more on the former
than the latter. Get over it. That's just the way it is. Design
systems that recognize such requirements.

The ITU report recently circulated infers from the (non-unanimous)
support within WP7A for emasculating UTC that some consensus has been
reached. Rather, the disagreements that continue year after year on
this mailing list are closer to expressing the true fact that no such
consensus exists. In the absence of consensus, no decision should be
taken. Conferences and other opportunities for face-to-face debate
and wrangling, research publications detailing the logistical,
technical, historical, sociological, political, scientific and other
aspects of civil timekeeping should be produced. Grants should be
pursued to carry out this research. Proper system engineering best
practices should be followed to conduct trade-off studies and risk
analyses, and so forth and so on.

Why is this controversial?

At the very least, someone promoting this proposal should show the
rest of the world and themselves the respect of creating some sort of
actual plan for what options might exist when the embargoed leap
seconds turn into minutes and hours. The proposal is intellectually
embarrassing as it stands.


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