Re: [LEAPSECS] building consensus

From: Rob Seaman <seaman_at_noao.edu>
Date: Mon, 5 Jun 2006 11:07:00 -0700

On Jun 5, 2006, at 8:45 AM, Warner Losh wrote:

> Leap days have an iron-clad rule that generates the schedule on which
> they happen. Leap seconds have a committee that generates the
> schedule on which they happen.

Further discussion in this thread calls into question the
characterization of "iron-clad rule" :-)

One might ponder what standards body is responsible for the
international calendar specification. Is it the Roman Catholic
church? Or has the specification passed into the public domain? Are
individual nations each responsible for their own calendars? If so,
mustn't they then be responsible for trade and scientific purposes
for providing tables of conversions between their national calendar
and the international standard? Which then returns us to the
question of who is responsible for that international standard...

> We have discussed having some kind of rule for when leap seconds
> are inserted.

Yes, but note that the IERS could institute a wide variety of
scheduling algorithms *on top of* the current monthly (or twice
yearly) leap second constraint. If the state of the art allowed
predicting UT1 for a decade in advance, a table of leap seconds could
be provided a decade in advance. This option requires even less of a
change than the Absurd Leap Hour Proposal (ALHP).

On Jun 5, 2006, at 8:57 AM, John Cowan wrote:

>> On the other hand, I am sure we haven't exhaustively discussed
>> possible refinements to the leap second "scheduling algorithm". (And
>> ain't that a rule?)
>
> I thought the whole point was that while we had a rather good
> prediction
> of changes in the tropical year (viz. none), and therefore only
> have to
> dink with the calendar when the current error of about 8.46 seconds/
> year
> accumulates to an uncomfortably large value, there is simply no
> knowing,
> in the current state of our geophysical knowledge, how the wobbly old
> boulder in the sky is going to wobble next.
>
>> The biggest difference between leap days and leap seconds is that
>> days are quantized.
>
> Can you expound on this remark?

A calendar counts days. A day - whether from noon to noon, midnight
to midnight, sunrise to sunrise, or sunset to sunset - is an atomic
"quanta" of time on earth. It also happens to be growing relative to
the year. Ultimately calendrical and clock issues are the same.
(The historical time horizons over which various effects matter for
various purposes may be very different, of course.)

The ALHP is an attempt to redefine the day.

On Jun 5, 2006, at 9:27 AM, Zefram wrote:

> In the realm of calendars the terminology is "arithmetic" versus
> "observational". That's one of the things I included at the start of
> this thread. I'd also like to throw in the word "deterministic".

> The Gregorian calendar itself is strictly arithmetic and thus
> immutable.
>
> There is the alternate point of view that the calendar in actual
> civil use
> in a particular locality, changing between different arithmetic
> calendars
> at different times, constitutes an unpredictable observational
> calendar.
> Perhaps we need a concept of "calendar zone" analogous to time zone,
> with a calendar zone database to match.

So the calendar is either immutable - or it isn't :-)

I have a hard time reconciling the notion of a "calendar zone" with
the definition of "deterministic" as:

        "an inevitable consequence of antecedent sufficient causes"

For the sake of argument, however, assume that the Gregorian calendar
is immutable - leap day every four years, except for even centuries
not divisible by 400. What will then happen when the Gregorian
calendar is inevitably deemed to fail to serve? Well, we already
have historical precedent. The Gregorian calendar succeeded the
Julian, just as the Julian succeeded what came before. That Caesar
was more successful than Pope Gregory at convincing the world to
rapidly adopt the new standard is a result of some pretty interesting
historical differences between the two eras. The fundamental fact,
however, is that a new calendar was completely substituted for the
old. One might also note that the staged and delayed politically
sensitive adoption of the Gregorian calendar was possible precisely
because the Julian calendar continued in force. In fact, it
continues as a standard to the present day. The Julian calendar was
deprecated, but not redefined.

Compare this with the ALHP. I might disagree quite strongly with the
idea of a leap hour - but I wouldn't have quite the visceral hate and
utter contempt for the idea if the proposal were to also substitute a
new name. Instead of eviscerating UTC (a coherently defined entity
that the ITU simply inherited), call it "McCarthy Time", for
instance. One would think that just as the Julian and Gregorian
calendars pay homage to Julius Caesar and Pope Gregory, that the
eponymous "MT" would be taken as homage to its creator...

...and if not, ask yourself, why not?

In what ways is the ALHP unworthy of its authors?

Rob
NOAO
Received on Mon Jun 05 2006 - 11:07:35 PDT