On Tue 2010-11-02T13:30:42 -0400, Finkleman, Dave hath writ: > We must correlate time as perceived in our analyses > with the temporal relationships among objects in the universe.
For the sake of operational systems I would phrase this as the requirement that all precision intercomparisons of time, i.e, the difference between any two measures of time, need a lookup table in order to communicate the information. Thus in POSIX systems we have the zoneinfo file and the leap seconds file. For the most precise of all systems we have the NIST publications of the differences between UTC(NIST) and GPS time, the publications of the same by USNO and every other national metrology agency, and the BIPM publication Circular T. For historical purposes this requires archival publications by BIH of the predecessor of Circular T, the various papers by Stephenson and Morrison, and the observing logs of various meridian circle instruments. For civil purposes this includes the records of local and national legislation and decrees by various authorities. By which I say that nobody can tell me what time it is, and neither can I say it. All I can do is to say what my clock reads, to keep records of how that agrees with other clocks, and to design systems that tolerate and/or recognize the differences. Unfortunately many systems have been designed with the presumption that there is a simple, unique answer to the question "What time is it?" -- Steve Allen <s...@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855 University of California Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
