Re: [LEAPSECS] Precise time over time

From: Rob Seaman <>
Date: Fri, 5 Aug 2005 16:28:26 -0700

The metaphor between time and Moore's Law should be used with care.
In astronomy we've recently been subjected to overheated rhetoric
comparing such things as telescope aperture and CCD real estate to
poor Mr. Moore. On the other hand, comparisons to Moore's Law are
themselves a question of the precise shape of some curve. Is growth
linear or exponential? This changes not only the magnitude of an
effect, but its nature.

Tom Van Baak says:

> Things are more precise now; trains in Japan or Europe,
> synchronized traffic lights, TV show times, TiVo, 911 calls, ATM
> withdrawls, top of the hour radio broadcasts, stock and currency
> transactions, and such. My favorite example is eBay. It seems we
> are now in a world pushing an accuracy level of 1 second. (though,
> there are plenty of farmers who just need to know what day Spring
> begins)

We need to use the concepts of "precision" and "accuracy" with care.
Too often over the past half dozen years Solar Time has been equated
to neolithic hunter-gatherers and Atomic Time to the space age. The
reality is that both are third millennium concepts and deserve third
millennium solutions. I also question whether systems requiring
highly synchronized worldwide frequency standards are a very robust
solution. When I call 911 somewhere off the grid in the western
U.S., I hope the response doesn't depend on the sheriff's atomic
pocket watch remaining slaved to Paris.

The April Fritillary is an English butterfly that emerges from its
chrysalis in March. The discrepancy is due to the two century lag in
the English adoption of the Gregorian calendar. (I'm sure someone
will correct my recollection from two semesters of the history of
astronomy a quarter century ago.) My point is that we have already
seen a large historical upheaval directly connected to the date that
Spring begins. One might also point out that a 21st century farmer
is likely as wired as any other profession - more so than most.

Any size upheaval related to UTC is unnecessary and unacceptable. A
consensus should be built in advance of any change to civil time.
Considering options other than the complete destruction of UTC would
be a good place to start. I believe you will find that:

     A) Astronomers are willing to entertain quite creative solutions.
     B) Different astronomers (and astronomical programmers) have
different ideas.

Rob Seaman
National Optical Astronomy Observatory
Received on Fri Aug 05 2005 - 16:28:46 PDT

This archive was generated by hypermail 2.3.0 : Sat Sep 04 2010 - 09:44:55 PDT