Re: [LEAPSECS] "names for points in time"
On Fri, Jan 31, 2003 at 12:28:28AM +0000, ut1-mail_at_ASTHE.COM wrote:
> > I think
> > the historical fact that people used to treat the earth's rotation
> > as the ultimate reference for the passage of time is not the most
> > relevant factor in the determination of how we should measure time
> > going forward, though history and tradition do need to be honored
> > and not gratuitously thrown away.
>
> Here we may have to agree to disagree a bit here.
Perhaps, but I am still not sure that we really disagree... my main
goal in statements like the above is to pick at the question of
"why is spatial orientation important"; sometimes the only way I
know of to pry at latent assumptions, trying to shed light on them,
is to belligerently question some closely related irregularity.
I'm not trying to say that tying time to earth orientation is
fundamentally wrong; I am trying to ask that the reasons that people
feel that the relationship should exist should be made explicit.
_Maybe_ with the reasons made explicit, they will be seen to be
spurious, or maybe they will be seen to be important, whether for
technical or political/cultural reasons. But I can't guess which
without prying the assumptions out into the light of day.
> Much of the driving force behind calendar/time reform has been driven
> by increased understanding of the spatial orientation of the Earth.
Right, that is the history of how we got where we are. It is a
description of the tradition. It does not illuminate any technical
merits or demerits of the situation.
> This increased tie between "names for points in time" and "spatial
> orientation of Earth" has been one of the fundamental factors behind
> calendar/time reform for a very good reason: it mattered to key people.
And the key people called upon their experts to solve specific
identified problems. My beef with this is that I know how easy it
is to answer the question asked without questioning what the real
motive behind the question is. I have several times experienced a
situation where I would answer a question as-asked, and later find out
that the querent could have both saved a lot of effort and obtained
a better result if only they had asked me "the question before".
What I mean by that is: they had hit a problem and figured out how
they could solve the problem if they could solve some subproblem;
I was asked a question about the subproblem rather than about the
first-experienced problem. Sometimes I'm paying attention and notice
a strange "why would you want to do that?" aspect to such second-order
questions and seek out what it is that they're _really_ trying to do;
this leads to much happier outcomes, and is very similar to what I
am attempting to do here on LEAPSECS --- understand what the basic
problems that need solving are, rather than trying to just come up
with a fix for the challenge du jour.
> And the vast majority of the rest put up with years not having
> 360 days, or lunar months nor staying in sync with the solar year,
> mean solar vs local solar time, time zones, or leap days ... some
> objected when these reforms were introduced (a few still object)
> but most people have come around to the same idea.
There are some assumptions built in to our calendar system and
it leap year rules also (such as: the vernal equinox should fall
within two days of March 21st). There are tradeoffs involved in
any attempt to make any pair of incommensurate methods of counting
(such as SI seconds and days, or days and years) peacefully co-exist.
The keeping of tradition is a valid consideration, I just want the
requirements of a system, and the reasons for why the requirements
are deemed to be important, to be clearly laid out.
> Now we have some people who seem to dislike uncertainly, wanting to
> reduce the relationship between names for points in time" and "spatial
> orientation of Earth". I think it would be a unfortunate step backward
> if our calendar/time became less tied to the "spatial orientation of
> Earth", IMHO.
Okay. I disagree with the "step backward" part of that statement
(even though it *is* a statement of opinion), but I can accept that
you would find it unfortunate to break the connection between the two.
So if I can hazard a restatement of your opinion into a form suitable
to what I'm after:
A time standard should maintain a meaningful relationship between its
measure of a day and the orientation of earth with respect to the sun
because: on a technical level the choice of maintaining or breaking
this coupling is a purely arbitrary one, and the choice of keeping
the two coupled gives continuity with long standing tradition.
Is that accurate? Did I miss something? I find it a pretty good
argument myself, unless someone can show that the claim about the
choice being arbitrary from a technical point of view is wrong.
And while I don't personally see any reason why that claim should
be wrong, at least now the issue is out on the table to be clearly
examined.
> For those who feel that "names for points in time" should be less
> tied to the "spatial orientation of Earth", use something TAI-like.
> For those who have problems with the chaotic / complex motions of
> things such as the Earth, use something TAI-like. For those who worry
> about the unpredictable nature of leap seconds (or even anti-leap
> seconds), use something TAI-like.
Right. The question as I see is: should a TAI-like time be the
central standard, or a technical side-line? The "kill UTC" (to
overstate it) crowd would prefer TAI to be central, and let those who
care about UT1 obtain that in some secondary way. The status-quo
is that UTC (and DUT1 estimates) are fairly readily available, but
those who want TAI-like time need to obtain and maintain a list of
UTC-TAI differences. Who is right? Both; neither; the question is
meaningless without a definition of what "right" means.
> For me personally: my computers, and my precision clocks deal with
> leap seconds rather well. And I have no problem with accepting that
> future "names for points in time" are uncertain. I think that is a
> fair cost for using a time scale that is tied into the "spatial
> orientation of Earth".
It may well be. Personally, I'm not yet convinced that the tradeoffs
involved in either approach have been enumerated thoroughly enough
to be able to give an accurate weighing of the relative costs.
> All the above is just my humble opinion ... you opinion may vary.
> I accept and respect that.
Likewise, I can accept and respect your opinion. My opinion *does*
vary (sometimes as often as four times a day), and I am still seeking
enlightenment as to why those who have a fixed opinion are holding theirs,
in order to make up my mind.
--Ken Pizzini
Received on Thu Jan 30 2003 - 18:47:27 PST
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