[LEAPSECS] Straw men

[Rob Seaman]

Ian Batten wrote:


> Clearly a day which consists of 86400 SI seconds isn't a mean solar day over any extended period of time.


Indeed.


> One of "86400" or "SI" or "a day runs from mean noon to mean noon" has to go at some point many thousands of years out.


A good place to start, although there is also a family of solutions that handle the daily epsilon corrections explicitly.  Sort of like compounding interest.  These include, from Mark Calabretta:

	http://www.ucolick.org/~sla/navyls/0459.html

(Who was also quite eloquent that a leap second is purely a representational overlay of TAI.)  And Steve Allen's TZ database concept:

	http://www.cacr.caltech.edu/futureofutc/preprints/45_AAS_11-681_Allen.pdf

Several of us find the notion of attempting to redefine the word "day" singularly unconvincing:

	http://arxiv.org/abs/1106.3141

There has been widespread agreement that lengthening the scheduling horizon for leapseconds would help, e.g., see the final slide of:

	http://phk.freebsd.dk/pubs/usno_slides.pdf

Or the "Extended Prediction" paragraph on p.9 of:

	http://www.cacr.caltech.edu/futureofutc/preprints/01_AAS_11-660.pdf

As well as various messages here.


> Does my watch, set to widely available timescales, allow me to catch trains on time?  That's pretty much the beginning and end of civil time.  Literally, as that's pretty much how civil time arose in the first place.


And yet many arguments here have proceeded from the observation that civilians rely on complex modern infrastructure.  For instance, a lot of telecommunications depends on satellite technology, hence the sponsorship of the Future of UTC meeting by the American Astronautical Society and the American Institute of Aeronautics and Astronautics.  Modern technology depends on both kinds of timekeeping.  A conceptual model recognizing the distinction is necessary.

Rob