[LEAPSECS] Schedule for success

Rob Seaman seaman at noao.edu
Mon Dec 22 19:37:39 EST 2008

M. Warner Losh wrote:

> We should really consider if it still matters to have things based

> on mean solar time at an arbitrary meridian, or if such a coupling

> really matters at all. This is the crux of the debate: I think it

> is silly, you think it is so obviously critical that we can't find

> common ground on this point.

Actually, if this mailing list had any influence on policy-making, I
suspect we could easily find common ground. These discussions are
nothing compared to some other working groups I've seen :-)

I have failed to make my argument clear that civil timekeeping is
equivalent (in the sense of a mathematical identity) to some stable
approximation to mean solar time. I don't really need to make this
argument, because the solar system will make it for me in the fullness
of time :-)

Which is to say - you appear to believe that I am insisting on some
sort of whimsical policy choice. Rather, it is a trite truism. The
coupling you mention matters because it actually exists. The issues
are how much the coupling matters, and what level of approximation is
sufficient, and how shall it be implemented. There is room for all
the different notional positions that have ever been mentioned on the
list. However, how well those positions are evaluated depends on
appropriateness of the mental model used.

Over and over again - certainly within the ITU proposal - arguments
are made based on the assumption that the underlying timescale is a
free parameter. This is simply untrue. Solid arguments can't be
built on faulty premises. A day cannot be redefined to have 100,000
SI seconds. It likely cannot be redefined to have 86401 SI seconds.

From the top: Since the SI second was defined to be close to the
mean solar second, it is possible for the ITU to cheat for a while.
Eventually this will no longer be acceptable. It doesn't seem too
much to ask, for instance, that their proposal actually include a
sunset provision. (Pun noted.)


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