[LEAPSECS] it's WP7A week in Geneva

[Rob Seaman]

M. Warner Losh wrote:


> Actually, that solution does keep UTC coupled to the sun.  I tend to  

> agree that large adjustments like that would never happen.


Timezones are an hour wide.  Any such adjustment would only occur  
after the entire error budget propagated all the way across.  This is  
equivalent to no solution at all.  I wasn't addressing the issue of  
"coupling", but rather the more basic issue of "solving the problem".


> The idea there would be to publish the UT1 and not worry that it  

> grows without bound.  Then you don't have to coordinate the  

> insertion of leap seconds, just publish a measurement that says what  

> the delta is.


I won't critique this notion now, but if this is part of the solution  
shouldn't it be addressed in the proposal?


> What isn't addressed is keeping them in sync.  They are two  

> different things, and we shouldn't lose sight of that fact.


Ok - that's two rather obvious things that are missing from the  
proposal.


> And embargo on leap seconds forever is exactly the same thing as  

> saying UTC is no longer tied to the sun.  That's a change that  

> should be considered, even if it ultimately proves to be not a  

> viable change.


And the status quo should also be considered in any trade-off study.   
As well as entertaining the Torino consensus of leaving UTC alone by  
defining a new timescale unencumbered by annoying astronomers. And the  
numerous interesting variations of the zoneinfo concept.  Or simply  
distributing GPS time instead of UTC.


> This is a proposed solution, and one that may have merit.  However,  

> only if the users of time for which it actually matters that DUT1 is  

> < 1s can get the larger corrections from somewhere else, retool,  

> etc.  These costs may be smaller than continued insertions of leap  

> seconds (they could very well be larger too: nobody has done a  

> public, comprehensive study here).


I'm all for coherently studying the issues.

The heart of my argument, however, is distinct from the need to  
constrain DUT1.  Rather, civil time is obviously a flavor of mean  
solar time (sidereal time plus the offset for lapping the Sun every  
year) - see list archive for discussion(s).  In fact, the small  
cadence of leap seconds at the current epoch is the only reason an  
embargo can even be entertained as an option.

We can productively debate non-UTC options or different scheduling  
strategies or different transport infrastructure or different  
tolerances, but night divides the day and the leap-second is  
ultimately a mechanism to keep the definition of the day stationary.   
Embargoing leap seconds is an unworkable strategy because the rate  
also matters, not just local offsets.

Rob