Poul-Henning Kamp wrote:
In message <[EMAIL PROTECTED]>, Rob Seaman writes:
Pop quiz! What is the length of the day? No tricks - no gimmicks.
Launch a tee-shirt to that guy in the last row. Right you are! A day on Earth
is 23h 56m 4s.
Now, for two t-shirts:
Which fraction of the earths population would disagree with the answer that
astronomer gave ?
Right there in front: 99.999% sounds about right.
Now, for 3 t-shirts Poul, reread Rob's last paragraph, but this time with your
blinders removed.
[-----Rob Seaman's last paragraph-----]
It is very telling that arguments such as PHK's always seem to be based on
solar time. After all, the spinning Earth
forms a steady clock relative to the fixed stars, not the Sun. The length of the day
"really, truly" is 23h 56m 4s.
Why is this never pointed out? Because it simply isn't so for most purposes.
A day in the life is a solar day. It
is the solar day our clocks should characterize. That the Earth's orbit is
elliptical, its axis tipped, and that it is
circled by the Moon simply underscore the need for civil time to follow mean
solar time and thus bring clarity to our
timekeeping. It is precisely the overwhelming dominance of the Sun in our
everyday lives that illuminates the clear
choice of basing civil time on solar time. It is just as wrong for the
precision timing community to embrace the
split second (but growing) errors of raw TAI as it would be to permit the
nearly four minute daily error that sidereal
clocks would impose on our lives.
[-----Rob Seaman's last paragraph-----]
You can agree to disagree, but Rob was using the 23h 56m 4s sidereal day as a
parable, not as an actual
suggestion that we all abandon solar/seasonal time.
Neither of you is as dumb as you think the other to be.
-Chuck
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