[LEAPSECS] Degrees of Accommodating Time Based on Earth Rotation

[Poul-Henning Kamp]

In message <3B33E89C51D2DE44BE2F0C757C656C88099AAC8C at mail02.stk.com>, "Finklema
n, Dave" writes:


>It is a hierarchy each level of which is sufficient for a range of

>applications.  Every time we solve dynamical equations, we are defining

>a unique time scale and time interval based on things such as analytical

>discretization and computational architecture.  


That is a good summation and an interesting way to look at it.

I would put leap days on top of the heap of approximations, even
though that is a different physical rotation, simply so they appear
on the list and people don't ask stupid questions.

So here is an instructive little table:

Finagle					Subject to
Factor		Unit/Resolution		politics since
------------------------------------------------------------
Leap days	86400 sec.		2000 bc.
Timezones	3600 sec.		1884
Leap seconds	1 sec.			1958/1972
DUT1 (Bul. A)	1 microsec.		Not yet
------------------------------------------------------------

Politization of these finagle factors have always been
motions toward higher predictability:

We went from priests announcing Easter based on astronomical
observations, to putting them on a mathematical formula that could
predict the dates for future, as far as we can see it.

We went from random local timescales to UT[C] with 24 standardized
timezones.

We went from rubber seconds to identical seconds.

In that light, it seems awfully logical that we would want to
nail the length of the days down also...

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