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

Mike S mikes at flatsurface.com
Fri Jul 15 23:05:02 EDT 2005

At 07:07 PM 7/15/2005, M. Warner Losh wrote...
>In message: <8366C59E-C587-4DF6-ABB0-9A9D92008DDC at noao.edu>
>            Rob Seaman <seaman at noao.edu> writes:
>: Historians may care deeply about whether some event  
>: occurred on one day (as defined by the Earth) as opposed to another  
>: day (as defined by mid-level international bureaucrats).  Religious  
>: issues anybody?
>We already have ambiguity in when something occurs, as defined by
>Earth.  Each timezone is 15 degrees wide, and thus something may
>happen at 11:59:59pm local standard time, but really happen at
>12:01:01am the next day 'solar' time.  We lost earth local time when
>we went to a standard time years ago.

Nothing is lost, mathematics and geographic position take care of that. You miss the point - UTC provides a geo-referenced timescale with atomic accuracy and linearity. From that, local mean solar time can be calculated unambiguously and contemporaneously. No other existing time scale provides that. TAI (or TT) already exists and provides deterministic future times, exactly what the proponents of a radically changed UTC claim to want. 

Furthermore, changing UTC does not eliminate the need to deal with leap seconds. There are already 30 years worth which will always have to be accommodated in time calculations spanning the period during which they are used. Eliminating future ones simply creates a timescale which is the worst of both worlds, it is neither earth locked (like UTC), nor does it eliminate having to handle leap seconds (like TAI).

Fact is, what proponents of a UTC lacking future leap seconds really want is to rewrite laws and regulations outside of the legal and regulatory systems, which were predominantly written with respect to mean solar time (aka GMT/UTC). It is not a technical or scientific matter, or they would simply use TAI, which already exists and provides what they claim to want. It's political. They've had 33 years to learn to deal with leap seconds, and having failed miserably in that very simple task, instead of having time revolve around the earth, now want it to revolve around _them_. 

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