[LEAPSECS] UTC Redefinition Advanced

Jonathan E. Hardis jhardis at tcs.wap.org
Tue Nov 2 19:28:53 EDT 2010

On Nov 2, 2010, at 11:05 AM, Rob Seaman wrote:

> On Nov 2, 2010, at 7:06 AM, Clive D.W. Feather wrote:


>> The reason I haven't been involved in this thread up to now is that

>> I spent the last week in a place where apparent solar time and

>> official clock time were about 7800 seconds apart. It was quite

>> curious being near the tropics and yet at 08:30 the sky was still

>> dark.


> ...


> Eliminating leap seconds would introduce a permanent secular trend

> (no matter how small).

So the 30 messages in my in-box this evening arose from a belated
reply to I message I posted a week ago. Oh, well.

Rob ... you're absolutely right. Eliminating leap seconds WOULD
introduce a secular trend ... IF (and here's the part I haven't
convinced you about yet) no other means for compensating for it is
implemented, FOREVER AND EVER.

This is not what the ITU is discussing. They are not making policy
FOREVER AND EVER. They are dealing with a much more limited
question: are occasional, sporadic, and unpredictable leap seconds,
that much of our infrastructure has difficulty dealing with, an
appropriate means of dealing with the secular trend TODAY?

Society -- and computers -- don't seem to have much problem with leap
years, which occur on a preset schedule every 97 years out of 400.
Why shouldn't leap seconds be constructed the same way? If the ITU
makes the decision to allow DUT1 to exceed 0.9 second, then some
decades from now the ITU could reintroduce leap seconds -- with years
of advance notice -- on a regular once- or twice-a-year schedule. In
the meantime, as long as DUT1 remains under a couple of hundred (which
would take centuries to happen), the public is apt to be less
inconvenienced than they are with the present system.

- Jonathan

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