Hi David:
My concern is that if the time between leaps gets to be long then there
will be another Y2K type problem. I.e. programmers will ignore the Leap
Hour, figuring that they will be dead when it occurs, and when it does
there will be many broken programs.
The GPS time scale does not have leap seconds. Would it be suitable for
those applications where leap seconds are a problem?
Have Fun,
Brooke Clarke, N6GCE
--
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
David Forbes wrote:
At 11:13 PM -0700 7/13/05, Rob Seaman wrote:
Howdy,
This is a little missive from an astronomer on the delicate subject
of the divergence of UTC from UTx. It seems that those bastards in
the precision timing community want to abandon UTC's leap seconds
entirely because they are too much trouble, and he's hopping mad.
Note that my message was composed for astronomers, not you guys.
Several of us in the astronomical software community have been
following this issue since before Y2K:
http://www.ucolick.org/~sla/leapsecs
We are as "hopping mad" about the sneaky process as about the
proposal. Note our two tiered objection: they not only propose to
cease issuing leap seconds, they propose to continue calling the
resulting time scale "Coordinated Universal Time". There are many
flavors of UT - UTC should not be divorced from the others. Call a
leap second-less civil time anything you want - simply don't call it
"UTC".
I agree that important processes should not be sneaky, but they often
are. Manhattan Project, anyone?
[His most amusing argument against modifying UTC is that astronomy
software tends to use UTC not UT1 etc.]
Amusing how?
It's amusing in that UTC is civil time, not astronomical time, which one
would expect astronomers to use. I didn't say it's bad or wrong, just
that it's amusing. Jokes are amusing. I have a sense of humor, which
many people seem to lose when their favorite ideas are attacked.
Also note that UT1 is only available after the fact. UTC is a
deterministic (if segmented) timescale which provides not only an
approximation (and prediction) of UT1, but also provides access to TAI
two or three orders of magnitude more precisely yet. It may not be
perfect, but then - this proposal isn't designed to provide something
better. Imagine what might have been achieved if the precision timing
community had spent the seven year leap second hiatus working to
improve UTC rather than to sabotage it.
UTC is NOT deterministic. It has leap seconds inserted randomly with
only 6 months advance notice. You can't plan a mission to Saturn based
on UTC.
There was a big discussion about this subject on the time-nuts list a
couple weeks ago precisely *because* UTC is not deterministic. Computer
programmers have to stand on their heads to design systems to calculate
future time using UTC.
I find it surreal that it is the precision timing community who are
arguing that the public have no need for access to precision time.
The time the public uses doesn't need to be locked to the Earth's
rotation to within a second over the short term. The thing to solve is
the long-term drift, which can be predicted far in advance, but not to
within a second a year.
I propose a better solution that will keep the civil timescale locked to
the Earth's rotation to within a minute and be deterministic for
hundreds of years in advance: Create leap minutes and *define them in
advance* for the next 500 years (or however far in advance is practical)
based on the second-order curve of the known characteristics of the
Earth's rotation. Then the programmers will have an algorithm to
guarantee that their clock code will work until long after they're dead.
Rob Seaman
NOAO
_______________________________________________
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
_______________________________________________
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
