On Jul 16, 2005, at 12:07 AM, Poul-Henning Kamp wrote:
No, you can not tell me today how many seconds between now and 2010-01-01 00:00:00 UTC and that is the whole problem.
That is *part* of the problem - a part that is intrinsic to living within a non-inertial reference frame. Folks who need interval time such as you describe should use TAI.
The entire point here is to make UTC be a usable timescale without having to put all military personal, all civil servants, all school teachers, all emergency response personel and all programmers through a reeducation.
UTC is a usable timescale - in fact, it conveys two usable timescales: TAI for interval time and an approximation of UTn for time-of-day. In point of fact it conveys TAI with at least two orders of magnitude higher precision than UTn - it is already more of a TAI standard than a UTn standard. All of the people you describe expect civil time to be responsive to the rotation of the Earth, few care about leap seconds one way or another. Most clocks are, and will continue to be, unaffected by leap seconds since they are embedded in systems that require resetting more frequently than the secular drift can build up. Most clocks and users of clocks are deeply affected, however, by the underlying nature of the civil timescale. Try to "reeducate" the public to understand that each day will no longer begin and end at midnight - that the prime meridian is drifting out to sea - that "atomic" clocks (with all the 20th century baggage of that word) are more important than mother Earth. The "leap second deauthorization proposal" is not only a naive technical "solution", it is astoundingly bad public relations for the precision timing community. Having castrated the world's clocks, should the PTC expect new funding to be forthcoming to clean up the mess they've created?
Those clocks and systems and projects and people that *are* affected by leap seconds should have implemented the civil time standard that was in effect when the clocks were designed and built. A professional builds to spec even if he has a philosophical disagreement with it. The real issue here is that the "medium- precision" timing community built lots of clocks and clock-like systems without ever bothering to investigate the underlying issues of timekeeping. The clocks aren't built to spec, because nobody read the specification. It was the ITU's responsibility to promulgate the UTC specification. Are we now to trust them when they want to abandon it?
There will be no need to reeducate anybody if the civil time standard is left unchanged. Part of what is going on, however, is the simple and inevitable *education* of technical personnel whose projects have run afoul of previously unexamined real-world constraints.
Rob Seaman National Optical Astronomy Observatory _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
