A long flight was time to really read Ken Seidelmann's book and part of Woolard and Clemence, Spherical Astronomy. Subsequent exchanges with Ken give me a new understanding. (Probably an old understanding for the rest of you.)
When we solve equations approximating physical processes, we are really defining our own dynamical time scale. Even with well characterized initial conditions or observations and a well founded system of units, the clock in our analysis does not tick at the same rate as those based on real phenomena. We must correlate time as perceived in our analyses with the temporal relationships among objects in the universe. For Earth rotation, time zones are the most coarse correlation. For time measured in SI seconds, not related to external phenomena, leap seconds are the next most precise. Finally, DUT, is precise enough for most astronomical and astrodynamic applications. It is a hierarchy each level of which is sufficient for a range of applications. Every time we solve dynamical equations, we are defining a unique time scale and time interval based on things such as analytical discretization and computational architecture. Comments? Dave Finkleman Senior Scientist Center for Space Standards and Innovation Analytical Graphics, Inc. 7150 Campus Drive Colorado Springs, CO 80920 Phone: 719-510-8282 or 719-321-4780 Fax: 719-573-9079 Discover CSSI data downloads, technical webinars, publications, and outreach events at www.CenterForSpace.com. ************** _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
