[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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