Rob Seaman said:
> The question of delivering wall
> clock time is a trivial elaboration on first delivering common
> international business time. (I'm trying on different terminology
> than "civil time" until I hit one that sticks.)
I don't accept that the concept exists. The international business
community still works - as far as I can tell - on the equivalent of "Hello
Fred, what time is it there?".
> The event of migrating a time
> zone is a discontinuity just as with a leap second or leap hour.
So what? We go through such discontinuities twice a year in most years.
Some places more often. Read the TZ list archives.
> What matters is not when sunrise occurs, but rather that every day
> has one (and only one).
Something which isn't and hasn't been true in many places.
What time is sunrise in Tromso today?
What time was sunrise on 1994-12-31 in eastern Kiribati?
>> If Denmark or Elbonia decides to use a timezone which is offset
>> from stage one by 1h3m21s, then it still works,
> Again, what is "it", precisely?
Life.
>> (but people travelling abroad will probably vote differently in the
>> next election)
> Exactly. The pressures to maintain a common international vision of
> time will trump local variations.
That's not pressure to maintain a common international vision, but people
not wanting to fiddle with the minutes and seconds on their digital
watches.
>> In a couple of hundred years, the Danish Parliament (or its
>> successor in interest) will simply decide "from YYYY-MM-DD HH:00,
>> the Danish Civil time will use offsets -3h and -2h (instead of
>> presently -1h/-2h) and the transition will happen on the switch
>> from summertime to wintertime by _not_ adjusting the clock".
> The only way this differs from the leap hour proposal is that you are
> assuming that different localities can (or would) carry these
> adjustments out separately.
>
> Let's see - how does this work?
Just the way that it does right now.
> Under the current standard, 3600 small steps
> would have bled away the pressure. Under the ITU notion, a leap hour
> would be needed. A leap hour means moving UTC backward one hour (to
> let TAI pull ahead). As I've said before, under the daylight saving
> analogy this is only naively a "fall back" event, it would be better
> to explicitly add a 25th hour. But let's continue through to the
> logical conclusion of implementing this via "fall back" events (or
> the equivalent time zone shifting).
Except that time zone shifting means you don't affect the UTC sequence.
> A fall back event means that the clock (local, standard,
> international, whatever clock you want) first traverses an hour - and
> then traverses it again.
Right.
At present, there's a meridian corresponding to UTC that starts at
Greenwich, drifts back and forth with secular changes in the earth's
rotation and, when it approaches Cutty Sark or the Dome suddenly jumps. The
proposal is simply to have this jump abolished, so that the UTC meridian
starts drifting around the earth.
> Um. How does one redefine the length of the day without changing the
> length of the second? Answer: by changing the number of seconds in
> the day. I won't belabor the difficulty of selling the idea of
> having different hours of different lengths.
You mean just like now?
--
Clive D.W. Feather | Work: <clive_at_demon.net> | Tel: +44 20 8495 6138
Internet Expert | Home: <clive_at_davros.org> | Fax: +44 870 051 9937
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Thus plc | |
Received on Mon Jan 09 2006 - 00:01:37 PST