Re: [LEAPSECS] Comments on Civil Time decision tree

From: Poul-Henning Kamp <>
Date: Mon, 26 Sep 2005 16:09:21 +0200

In message <>, Rob Seaman writes:

>I've appended what I call the Civil Time Decision Tree v0.5.

>I) Existence [Adopt an international (or intergalactic) civil time

Now, what we you mean by "civil time standard" ?

Most countries reserve the definition of "civil time" for their
national parliaments (or other some other tacitly assumed legitimate
political power).

They generally take UTC, apply a timezone and very often a DST

Other more laid back parliaments like the Danish have not been able
to find time to revisit the issue since 18xx and still use solar
time at some more or less random coordinate.

It would probably be wiser to recast this question in terms that do
not even hint at usurping sovereignty.

>II) Multiplicity [How many standards?]
> A) one
> B) many

Before we can answer this, don't we need to know the parameters of
the proposed standard ?

Ie: If UTC gets a one hour tolerance to UT1 then the answer will
obviously be "many" because the astronomers and geophysiscists will
need their own timescale (likely UT1).

On the other hand, even if we agree on one standard, or even just
leave UTC as it is, are the astronomers and geophysiscists going
to abandon UT1 ?

If so, then this is the first I've heard about it.

So as long as you include "scientific use" with "civil use", then
the answer to this question is "many" no matter which way you go.

Only if we agree that scientific use is specifically not included,
something which is strongly hinted in the use of the word "civil"
in the first place, does this question have any meaning.

>For each civil time standard:
>III) Locale
> A) restricted to Earth [projects or users, not necessarily
> B) other than Earth [e.g., Martian rovers]
> B) Solar system scope
> C) truly Universal

This question is also in trouble.

The crucial question here is not so much where you use it, that is
mostly just relativistic corrections to your clock model.

The relevant question is if you need to be able to hear from the
high priests of timekeeping in Paris on a regular basis or not.

Imagine for instance that we send a probe out of the solar system
at seriously high speeds and it manages to get as far as 6 light
months away: Under the current UTC rules we would be unable to
upload a leap-second warning and get it there before it is too late.


Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk_at_FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Received on Mon Sep 26 2005 - 07:20:44 PDT

This archive was generated by hypermail 2.3.0 : Sat Sep 04 2010 - 09:44:54 PDT