----- Original Message -----
From: "Daniel R. Tobias" <dan_at_TOBIAS.NAME>
To: <LEAPSECS_at_ROM.USNO.NAVY.MIL>
Sent: Thursday, December 14, 2006 5:45 AM
Subject: Re: [LEAPSECS] what time is it, legally?
> On 13 Dec 2006 at 21:43, Steve Allen wrote:
>
> > http://gauss.gge.unb.ca/papers.pdf/gpsworld.january01.pdf
>
> One quibble with that article is that it gives the Global Positioning
> System as an example of how humanity has been obsessed with knowing
> what time it is. Actually, GPS arises from our obsession with
> knowing what *place* we're at; its need for precise time is a mere
> technical detail of its implementation. (Some of the earlier
> historical needs for precise time also arose out of navigation, where
> knowing one's position in space necessitated also knowing something
> about time.)
>
All through this debate I've been struck by the parallels to the story of
John Harrison as described in Dava Sobel's _Longitude_. Like Harrison's
clocks, GPS provides both time and longitude for those with the means to
process the needed information out of the raw data. And, like the
18th-century debate between astronomers and "mechanics" (clockmakers), over
observational vs. synthetic means of determining position in space and time,
we now have a debate between those who believe our notions of time MUST
remain astronomically based and those who see more precise (and more easily
managable) oscillators--cesium atoms--as being the wisest choice for current
and future scientific purposes.
What the outcome of this will be, and who will be interested in any of this
discussion 250 years from now, remains to be seen, but the effects on future
timekeeping and related endeavors will most likely be just as significant.
The upshot: be careful what you say, gentlemen; someday, a descendent of
Sobel's may write a book about _you_! :)
Brian Garrett
Received on Thu Dec 14 2006 - 14:13:03 PST