Adi Stav wrote:
We know that human tolerance to DUT is higher than 20 minutes
because we
don't usually bother to compensate for apparent solar time. We know
that
it is probably not much higher than one or two hours because time
zones
generally have about that resolution. We guess that it is might be
about
one hour because many areas in the world choose time zones that are
about
one-hour offsets from their local mean time.
These justifications are not necessarily valid, or maybe there are
other
or better justifications for smaller DUT maxima. I am just trying to
find out (for myself) what these are. This is why I asked.
Ok (to the second paragraph :-)
Lower limits are hard to pin down. Human tolerance on a particular
day is not the same thing as the tolerance over a year or a lifetime.
Straining a tolerance for one human is not the same as straining it
for 6 billion. Human tolerances in general need to be interpreted in
terms of our infrastructure, not just personal perception as we walk
from parking lot to office.
The upper limit has been specified as a "statement against penal
interest" by the ITU. Public enemy number one of leap seconds says
an hour is the upper limit :-)
Embargoing leap seconds (or their equivalent) for periods of
decades or
centuries is the same as not making intercalary adjustments at all.
Why is that? Even the Gregorian reform does not come into effect
except
every one or two centuries. Yet it is followed exactly.
Gregory revised the Julian calendar. The fundamental standard remains
rooted in what the ancients discovered. The proper comparison is to
the every four year scheduling of leap day opportunities - sometimes
those opportunities remain nulled out, but they still exist.
The seasonal or diurnal trends in the calendar or clock need to be
sampled frequently enough to avoid significant quantization errors.
Leap seconds are productive from this point of view precisely because
civilians can ignore them.
By the way, it can be argued that the smoothness property is not
strictly
necessary for calendars. Consider popular and long-used artihmetic
lunisolar calendars, such as the Hebrew, Hindu, and Chinese calendars,
that intercalate their years to a resolution of a month.
A very interesting observation. What calendars does the world really
depend on for various purposes? That is, what is the market
penetration of the Gregorian/Julian calendar? I would guess nearly
100% in Europe and North America. What about the rest of the world?
Rob
_______________________________________________
LEAPSECS mailing list
LEAPSECS@leapsecond.com
http://six.pairlist.net/mailman/listinfo/leapsecs
