Re: [LEAPSECS] the legacy of ephemeris time

From: Steve Allen <>
Date: Mon, 22 Dec 2003 13:11:11 -0800

On Mon 2003-12-22T20:19:14 +0100, Poul-Henning Kamp hath writ:

> Time and effort, such as the above, spent on pondering the inconvenience
> potentially caused to civilizations a millenia, or even just a
> century in the future, is at best wasted, at worst in the way of
> our progress and the beneficial scratching of the current itch.

Then the Gregorian calendar reform was pointless, as the goal for
which it aimed will continue to be met for several more millennia.
Obviously we should have just stayed with the Julian calendar.
Curse that Pope, and those English MPs who voted for the change
two centuries later. They were all thinking way too far ahead.

> If we look back in history, there are a number of lessons to be
> learned about timescales:

> The lesson learned from leap-seconds is that infrequent, ad-hoc,
> minor adjustments are a bad thing. Mostly they are bad because
> they are not significant enough to be implemented in more than the
> most demanding applications, and in these applications we curse the
> fact that they cannot be predicted more than 6 months down the road.

This argument is simply not true for civil purposes.

Nobody can notice millisecond variations in LOD. The only trick is
managing to communicate them.

    Uncertainties in the time required for the workaday commute in
    most cities are many minutes.

    US viewers of Thursday night TV know that CBS always terminates
    CSI one minute after 10 PM, and NBC always starts ER one minute
    before 10 PM -- a true annoyance to VCR owners timeshifting
    programs. Transition variations between "live" programs on a
    24-hour news network are even larger.

These are variations in the daily routine a million times greater than
the non-uniformity of earth rotation. The first is unintentional, the
second is completely intentional. Nevertheless, civilization still

I assert that there is no need to disengage civil time from the sun
just to satisfy the users of precision time. Is there any argument
which can justify why civil time needs to be precise and uniform to a

If we go through the pain and split the current confusion of UTC into
a form of mean solar time and a form of atomic time interval have we
not satisfied all needs for time-like quantities, past, present,
and future?

Eventually (and this might mean 40000 years in the future) the
difference between earth rotation and SI seconds does become too
large. The future is hard to predict, but the people involved in
the ITU SRG will proably be judged harshly on their answer to this:

Will it really be cheaper to disengage in the far future after even
more systems depend on SI seconds, or should we start the process now?

Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064      Voice: +1 831 459 3046
PGP: 1024/E46978C5   F6 78 D1 10 62 94 8F 2E    49 89 0E FE 26 B4 14 93
Received on Mon Dec 22 2003 - 13:11:25 PST

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