Re: [LEAPSECS] Comments on Civil Time decision tree

From: Rob Seaman <seaman_at_NOAO.EDU>
Date: Mon, 26 Sep 2005 09:02:06 -0700

On Sep 26, 2005, at 7:09 AM, Poul-Henning Kamp wrote:

> 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
> ruleset.

Point taken that the language still needs to be defined. Of course,
some might find that additional support for the position that we are
in no way ready to decide on changes to civil time standards if we
can't even agree what civil time is.

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

Funny - my wife always says the same thing...

Whether it is called UTC, GMT or solar time, there is some coherent
international time scale concept underlying the individual choices
made by individual countries. That is what we are trying to define
(some of us, anyway). Isn't a suggestion that we ignore "natural
time" (based on whatever natural clock) in favor of "technology
time" (based on whatever ensemble of physical clocks we have built or
might build in the future) more likely to be viewed as an attack on
national sovereignty? After all, the current pastiche of legal time
systems successfully interoperate precisely because they are all
based on the concept of mean solar time no matter how obscure the
intervening standards process. It is the proposal to abandon leap
seconds from only SOME of the sovereign national clocks that
threatens interoperability.

I suspect that interoperability would be one issue we can all agree on.

> 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.

We already have many examples of the distinction between scientific
and civil uses of time. This discussion has never really been about
the former. If it was, then the folks pushing the ITU proposal would
have simply renamed their new timescale something other than UTC -
say, TI, as was decided in Torino. That would allow the astronomers
to continue to maintain UTC internal to their community which
undoubtedly would be a much less expensive proposition.

It is the folks who want to abandon leap seconds who are making an
unwarranted and unwise connection between civil time and science time.

> And that was exactly my point: "civil" and "scientific" timekeeping
> was
> two different issues and they have different semantics and needs.

Well, other than the fact that you are committing the same error in
assuming that there is one single scientific time scale, I agree with

> Most of this argument is still centered around the unarticulated
> question: "who owns UTC".
> Wouldn't it be fair if the non-scientific (ie: civil) world told
> the astronomers (and any other scientists) to bugger off and not
> impose scientific requirements on civil time ?

The flaw here is that you are excluding the scientific users -
precisely the folks who know how to address the issues - from helping
craft a solution. Scientists live in the civil world, too. Under
what circumstances are a few dozen committee members a world unto

It seems rather naive (the word "daft" also comes to mind) to suggest
that common sense "scientific" issues such as that civil time
obviously mimics solar time - to some level of precision we certainly
could discuss - have no place in making decisions about civil time.
Is the fact that the Earth rotates purely a scientific question? Or
is this something a typical Earthling might be expected to know?

> After all, scientists have several timescales of their own already,
> and plenty of means to implement them, whereas UTC is the only
> agreed upon and widely available civil timescale.

I agree - although there certainly is nothing to stop us from laying
international civil time upon some other underlying timescale like
"TI". The fact, that you appear to now be agreeing with, is that
there is one civil time standard. That being the case, we really
ought to labor to get it right, not to cut some inane deal with naive
corporate entities. I suspect plenty of the more cogent corporate
entities would reject the current proposal if anybody had thought to
ask them about it.

Rob Seaman
National Optical Astronomy Observatory
Received on Mon Sep 26 2005 - 09:03:00 PDT

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