[LEAPSECS] A new use for Pre-1972 UTC

Steve Allen sla at ucolick.org
Tue Feb 17 16:17:20 EST 2009

On Tue 2009-02-17T20:53:43 +0000, Poul-Henning Kamp hath writ:

> This is a variant of the UUID madness that somebody came up with

> because they didn't want to run a registry or use the existing

> well-structured process (ISO OID's) and though that the eventual

> collisions "probably doesn't matter much".

And the upshot is software that believes that the system clock is
always right. Or, more weakly, saying the system clock must be
monotonic -- but that is basically saying that if the clock ever gets
fast then it must stay fast. So if the clock gets wrong it must stay
wrong, or else at least it must get right in a fashion that is
consistent with that software's notion -- despite any side effects
that might have on the requirements of other systems that depend on

The fallacy that "my sense of time is always right" is what led to a
different kind of collision, the grounding of ships off Scilly in
1707, and the development of marine chronometers. The navigators who
used marine chonometers knew perfectly well that those chronometers
did not keep the "right" time as measured by clocks on land being
reset by telescopes. Instead they knew that if their chronmeters were
treated well they kept uniform time, and those navigators knew that
getting the "right" time meant keeping a log of the difference between
the "right" time of the clocks on land and their chronometer.

Steve Allen <sla at 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

More information about the LEAPSECS mailing list