[LEAPSECS] Reliability

Rob Seaman seaman at noao.edu
Sat Jan 3 10:09:28 EST 2009


Tony Finch wrote:


> (Um, do we actually know the earth's angular momentum and moment of

> inertia to any useful accuracy? I would have thought models would be

> based directly on angular velocity since that can be measured more

> precisely.)

>

> I think it's wrong to say that a directly measurable value (such as

> apparent solar time) is less real when measured than when derived

> from a model!

>

> Perhaps the word you are looking for is "fundamental".


And in several recent messages I've used the term angular velocity.

I'm happy with the term fundamental.

The point is that the Princes of the ITU, to borrow Steve Allen's
metaphor, sit in a hushed chamber (which might extend to Polycom
participants) and solemnly debate the future of time on Earth.

While they are debating this, it is a mental model they have about
timekeeping that guides the discussions. Their mental model clearly
must include the notion that mean solar time is dispensable - else
they wouldn't be trying to dispense with it.

The mental model of mean solar time is, however, indispensable. What
we are really debating is not how to change from one standard to
another, but rather how to enable two very different conceptions of
time to better coexist.

Nobody here has indicated an unwillingness to haggle. It seems like
we would all be delighted to see the leap second schedule extended in
some fashion. It appears a two or three year lead time is possible
even from a cursory look at the data. Even an extension from six
months to a year would be appreciated. Other possibilities exist.

Only the ITU has a completely immovable position - a position that
appears to be built on a faulty mental model.

Rob



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