[time-nuts] Re: UTC - A Cautionary Tale

Rob Seaman seaman at noao.edu
Sat Jul 16 12:32:41 EDT 2005

> Hopefully not too many people will be hurt trying to convince you.

Amen.  And hopefully any resulting lawsuits will assign blame and  
damages where they belong - with the financial backers and managers  
and designers of systems that failed to implement the appropriate  
international standard.  If a house burns down because a 110v  
appliance is plugged into a 220v line, whose fault is it?

Why are you so convinced that there couldn't possibly be negative  
ramifications associated with the unexamined assumptions underlying  
the distinction between time-of-day and interval time?  Or simply  
with the unwarranted assumption that one single timescale applies in  
all cases?  Claiming that "leap seconds are bad, we'll be safer  
without them" doesn't make it so.  Some systems will fail when DUT1 >  
1s.  Others will fail when their conceptual model of a timescale  
based on time-of-day collapses.  Still others will come in conflict  
with systems that they must interoperate with that make the opposite  
naive assumption, whatever it is.  Planes navigating via TAI versus  
planes navigating via UTn, for instance.  Control software for  
nuclear reactors whose build conditions are violated because some of  
the modules were timestamped before the great clock change of 2007  
and others afterwards.  Who knows what unchallenged assumptions will  
fail when they are later challenged by the real world facts of a  
secularly diverging DUT1?  I certainly don't - but neither do  
supporters of this dangerous proposal.  This is why a standards  
process should be open and inclusive.  This is why decisions  
shouldn't be left to narrow special interests.

The issue isn't with picking TAI on the one hand or UTn on the other  
- or even with continuing to support the rather elegant compromise of  
UTC that neatly conveys *both* interval time and time-of-day.  The  
issue is really that there are also many other timescales that are  
appropriate for various purposes - see http://tycho.usno.navy.mil/ 
systime.html.  Why are we not building systems that accurately convey  
the full richness of time?  Why are we not even discussing that  
possibility, but rather simply seeking to pretend that one single  
timescale fits all purposes?

>> "Mandrake, do you recall what Clemenceau once said about war?"
>> "No, I don't think I do, sir, no."
>> "He said war was too important to be left to the generals. When he  
>> said that, 50 years ago, he might have been right. But today, war  
>> is too important to be left to politicians. They have neither the  
>> time, the training, nor the inclination for strategic thought. I  
>> can no longer sit back and allow Communist infiltration, Communist  
>> indoctrination, Communist subversion and the international  
>> Communist conspiracy to sap and impurify all of our precious  
>> bodily fluids."

Time is too important to be left to the Time Lords.

Rob Seaman
National Optical Astronomy Observatory

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