On Mon 2007-01-01T21:19:04 +0000, Ed Davies hath writ: > Why does the "One sec at predicted intervals" line suddenly > diverge in the early 2500's when the other lines seem to just > be expanding in a sensible way?
Upon looking closer I see a 200 year periodicity in the plot. I begin to suspect that rather than run a pseudorandom sequence of LOD based on the power spectrum he instead took the past 2 centuries of LOD variation around the linear trend and just kept repeating those variations added to an ongoing linear trend. I suspect that the divergence of the one line indicates that the LOD has become long enough that 1 s can no longer keep up with the divergence using whatever predicted interval he chose. I suspect that the chosen interval was every three months, for it is in about the year 2500 that the LOD will require 4 leap seconds per year. As for the other questions, McCarthy had been producing versions of this plot since around 1999, but the published record of them is largely in PowerPoint. Dr. Tufte has provided postmortems of both Challenger and Columbia as testaments to how little that medium conveys. -- Steve Allen <[EMAIL PROTECTED]> WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99858 University of California Voice: +1 831 459 3046 Lng -122.06014 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m