Re: [LEAPSECS] Monsters from the id

From: Rob Seaman <seaman_at_noao.edu>
Date: Sat, 14 Jan 2006 02:09:20 -0700

On Jan 13, 2006, at 12:46 AM, John Cowan wrote:

> In the end, it will be impossible to maintain the notion that a solar
> day is 24h of 60m of 60s each: we wind up, IIRC, with the solar day
> and lunar month both at about 47 current solar days.

There's a lot of difference between what happens over a billion years
and a million years. Length of day increases only about 20s per million
years. Should we be here to care in a million years, only a 1/4 of
1/10 of
one percent tweak to the length of the "civil second" would suffice
to allow
our Babylonian clock paradigm to continue in use. Alternately, we might
decide to add one second to just one minute out of each hour.

I won't claim one of these would be the choice. There are manifold
options for representing time. But I do assert that our descendants
- for
as long as they may be regarded as human - will desire to have some
common way to represent fractions of a day. And no matter what
representation they choose, they will still face the quadratic
accumulation of leap seconds or their equivalent.

Far from being a motivating factor for deprecating leap seconds, the
quadratic clock lag resulting from the roughly linear tidal slowing of
the Earth is precisely the strongest argument for preserving mean
solar time as our common basis for timekeeping now and forever.

Besides, it is simply a charming fact of life in the solar system that
our Moon is receding while the Earth spins down. Apollo era laser
retro-reflectors show that for each second our day lengthens, the
Moon's orbital radius grows by a mile or so.

Time is a fundamental element of all that we do. Surely public
policy should not be governed by a drab and dystopian vision of
a fragmented planet scrabbling randomly to keep our disjoint
clocks aligned.

The simplest - nay, the only - way to keep our clocks synchronized
one to the other is to keep them all tied to Mother Earth.

        "You think the Earth people think we're strange you think."

Rob Seaman
NOAO
Received on Sat Jan 14 2006 - 01:09:46 PST