Re: Introduction of long term scheduling

[John Cowan]

M. Warner Losh scripsit:

> Since the interface to the kernel is time_t, there's really no chance
> for the kernel to do anything smarter with leapseconds.  gettimeofday,
> time and clock_gettime all return a time_t in different flavors.

It could be done in the C library, since the interface between the
kernel and libc is not defined, only the interface between libc and
userland programs proper.

> Kernels aren't written in these languages.

They don't have to be: the strong typing can be imposed by
convention.  ISO C got this right: a time_t can be any numeric
type, and difftime is used to find the seconds between two time_t's.
POSIX decided to stick with the old count-of-seconds rules for
arithmetic purposes, while making time_t no longer an actual count
of seconds, as V7 Unix defined it to be.

--
John Cowanhttp://ccil.org/~cowan[EMAIL PROTECTED]
Mr. Henry James writes fiction as if it were a painful duty.  --Oscar Wilde

Re: how to reset a clock

[John Cowan]

Rob Seaman scripsit:

> And, of course, a ship would not carry a single clock, but two or
> more.  Friendly ships meeting at sea would also exchange clock
> readings - creating the first ensemble time scale.  (Some things
> never change.)

English passenger at Irish railway station, pointing to the two clocks
at either end:  "Why don't those clocks tell the same time?"

Irish stationmaster:  "Ahhh, what would we be wanting with *two* clocks
if they told the same time?"

Eoghan Mac Eoghain

--
It was dreary and wearisome.  Cold clammy winter still held way in this
forsaken country.  The only green was the scum of livid weed on the dark
greasy surfaces of the sullen waters.  Dead grasses and rotting reeds loomed
up in the mists like ragged shadows of long-forgotten summers.
--"The Passage of the Marshes"  http://www.ccil.org/~cowan

Re: Introduction of long term scheduling

[John Cowan]

Warner Losh scripsit:

> There's no provision for emergency leapseconds.  They just have to be
> at the end of the month, and annoucned 8 weeks in advance.  IERS has
> actually exceeded this mandate by announcing them ~24 weeks in advance
> in recent history.

So much the worse.  That means that if the Earth hiccups on March 7, the
value of |DUT1| will not return to normal until May 31.

--
John Cowan[EMAIL PROTECTED]http://ccil.org/~cowan
The whole of Gaul is quartered into three halves.
-- Julius Caesar

Re: Introduction of long term scheduling

[John Cowan]

Warner Losh scripsit:

> There's an exception for IERS to
> step in two weeks in advance if the earth's rotation rate hickups.

So if I understand this correctly, there could be as many as 14
consecutive days during which |DUT1| > 0.9s before the emergency leap
second can be implemented; consequently, the current guarantee is only
statistical, not absolute.

--
John Cowan  http://www.ccil.org/~cowan  [EMAIL PROTECTED]
"After all, would you consider a man without honor wealthy, even if his
Dinar laid end to end would reach from here to the Temple of Toplat?"
"No, I wouldn't", the beggar replied.  "Why is that?" the Master asked.
"A Dinar doesn't go very far these days, Master.--Kehlog Albran
Besides, the Temple of Toplat is across the street."  The Profit

Re: A lurker surfaces

[John Cowan]

Zefram scripsit:

> Projecting into the future, one can foresee the eventual abandonment of
> timezones in favour of the universal use of Universal Time.

I think that's over the top.  Bureaucratically it is just too annoying
if the large majority of people have a work shift that overlaps legal
midnight.

--
On the Semantic Web, it's too hard to prove John Cowan[EMAIL PROTECTED]
you're not a dog.  --Bill de hOra   http://www.ccil.org/~cowan

Re: A lurker surfaces

[John Cowan]

Ashley Yakeley scripsit:

> Rubber seconds are appropriate because we have rubber days. People
> who need absolute time have their own timescale based on some
> absolute unit (the SI "second"), but to everyone else, the second is
> a fraction of the day.

Well, okay.  Does the rubberiness go down all the way?  Is a civil
nanosecond one-billionth of a civil second, then?  If so, how do we
build clocks that measure these intervals?


--
One art / There is  John Cowan <[EMAIL PROTECTED]>
No less / No more   http://www.ccil.org/~cowan
All things / To do
With sparks / Galore -- Douglas Hofstadter

Re: A lurker surfaces

[John Cowan]

Michael Sokolov scripsit:

> The people who complain about leap seconds screwing up their interval
> time computations are usually told to use TAI.  They retort that they
> need interval time *between civil timestamps*.  To me that seems like
> what they are really measuring as "interval time" is not physical
> interval time, but how much time has elapsed *in civil society*.

I think this point is quite sound, but I don't quite see what
its implications are (or why it makes rubber seconds better than
other kinds of adjustments).

--
John Cowan   http://ccil.org/~cowan[EMAIL PROTECTED]
We want more school houses and less jails; more books and less arsenals;
more learning and less vice; more constant work and less crime; more
leisure and less greed; more justice and less revenge; in fact, more of
the opportunities to cultivate our better natures.  --Samuel Gompers

Re: A lurker surfaces

[John Cowan]

Tony Finch scripsit:
> On Sun, 31 Dec 2006, John Cowan wrote:
> >
> > However, it's clear that UTC does not contain the sort of jumps
> > that LCT does, where a single broken-down time may represent
> > two different UTC seconds.
>
> Not if you include the timezone offset in the representation.

Quite so.  Or alternatively a standard/daylight flag.  The point is,
people usually don't.

--
John Cowanhttp://ccil.org/~cowan  [EMAIL PROTECTED]
'Tis the Linux rebellion / Let coders take their place,
The Linux-nationale / Shall Microsoft outpace,
We can write better programs / Our CPUs won't stall,
So raise the penguin banner of / The Linux-nationale.  --Greg Baker

Re: A lurker surfaces

[John Cowan]

M. Warner Losh scripsit:

> Well, if you count the variable radix notation as being 'continuous'
> then maybe you are right.  However, you never know when the radix is
> variable, hence the assertion on many people's part that UTC is
> discontinuous.

Indeed, one could say that *every* minute that does not contain
a 61st second represents a discontinuity.

However, it's clear that UTC does not contain the sort of jumps
that LCT does, where a single broken-down time may represent
two different UTC seconds.

--
I am expressing my opinion.  When myJohn Cowan
honorable and gallant friend is called, [EMAIL PROTECTED]
he will express his opinion.  This is   http://www.ccil.org/~cowan
the process which we call Debate.   --Winston Churchill

Re: Mechanism to provide tai-utc.dat locally

[John Cowan]

Rob Seaman scripsit:

> "Seems like"?  "Chances are"?  Pick some other random technical issue -
> say, automobile airbags, standardized educational testing, the lead
> content of pigment in children's crayons, and so forth and so on.
> Would "seems like" and "chances are" be phrases you would want to see
> in a white paper discussing the costs, benefits and risks of these?

Diffidently I suggest that if you think cost/benefit analysis has
*anything* to do with how international standards are set, you are
fairly unfamiliar with the actual process.

"Those who enjoy law and sausage should not watch them being made."

--
I don't know half of you half as well   John Cowan
as I should like, and I like less than half [EMAIL PROTECTED]
of you half as well as you deserve. http://www.ccil.org/~cowan
--Bilbo

Re: Mechanism to provide tai-utc.dat locally

[John Cowan]

Rob Seaman scripsit:

> Indeed.  Go for it.  I look forward to reading your report.  Who and
> what interests are adversely affected in each case?  How are these
> effects mitigated as a function of the limit on DUT1?  Also, contrast
> what benefits accrue.  One would think that the responsibility for
> quantifying the implications of a change to a standard would fall on
> the parties proposing said change.

It can't possibly be.  Nobody can know what a change is going to
cost except those who are going to have to pay for it (or not
pay for it).  And even their word cannot necessarily be trusted.

In this case there are really two questions:  how much it would
cost to loosen DUT1 but leave it bounded, and how much it would
cost if it were only statistically, not absolutely, bounded.

--
Don't be so humble.  You're not that great. John Cowan
--Golda Meir[EMAIL PROTECTED]

Re: Mechanism to provide tai-utc.dat locally

[John Cowan]

Rob Seaman scripsit:

> >I don't care if you want to implement leap-milliseconds, as long
> >as you tell me 10 years in advance when they happen.
>
> Again - with no intent to minimize the issues - what supports this
> assertion?  Is there any reason to believe that 10 years advance notice
> would encourage projects and vendors to do anything other than ignore
> the requirement entirely?  A statement that 10 years, or 600 years,
> notice is all that is needed to resolve all the problems, smooth over
> all the complications, is entirely too glib.

You are confusing the question of fixity (which is what notice is
about) with granularity.  It's true that probably no one would bother
to implement the ALHP.  However, if computer technologists were handed a
list of leap seconds from now until 2015, and told "Implement these," it
wouldn't matter how many or how few leap seconds there were.  But since
you astronomers insist on a fixed maximum for |DUT1|, no such table
can exist.

The proposal is this:  look at the trends, take your best shot at
working out a leap-year schedule for 10 years in the future, and then
live with it.

--
Newbies always ask: John Cowan
  "Elements or attributes?  http://www.ccil.org/~cowan
Which will serve me best?"  [EMAIL PROTECTED]
  Those who know roar like lions;
  Wise hackers smile like tigers.   --a tanka, or extended haiku

Re: Mechanism to provide tai-utc.dat locally

[John Cowan]

Tony Finch scripsit:

> Still, your minute/month system does not deal with variable-length days.

I assume you mean 23-hour or 25-hour LCT days?  True.  It does work
against UCT days, though, since they are uniformly 1440 minutes long.

--
Overhead, without any fuss, the stars were going out.
--Arthur C. Clarke, "The Nine Billion Names of God"
        John Cowan <[EMAIL PROTECTED]>

Re: Mechanism to provide tai-utc.dat locally

[John Cowan]

Tony Finch scripsit:

> How does your proposal deal with local time zone changes, e.g. "same
> time tomorrow", or times based on weeks, e.g. "last thursday in
> the month"?

Distinguo.  I am talking about time intervals; you are talking about
periodic events.  Two different things.

--
John Cowanhttp://ccil.org/~cowan[EMAIL PROTECTED]
SAXParserFactory [is] a hideous, evil monstrosity of a class that should
be hung, shot, beheaded, drawn and quartered, burned at the stake,
buried in unconsecrated ground, dug up, cremated, and the ashes tossed
in the Tiber while the complete cast of Wicked sings "Ding dong, the
witch is dead."  --Elliotte Rusty Harold on xml-dev

Re: Mechanism to provide tai-utc.dat locally

[John Cowan]

Rob Seaman scripsit:

> Mucking with leap seconds is equivalent to redefining the
> concept of a "day".

Very true.  And adopting the Egyptian-Roman calendar redefined
the concept of a "month".  Somehow civilization survived.

--
John Cowan   [EMAIL PROTECTED]   http://ccil.org/~cowan
I must confess that I have very little notion of what [s. 4 of the British
Trade Marks Act, 1938] is intended to convey, and particularly the sentence
of 253 words, as I make them, which constitutes sub-section 1.  I doubt if
the entire statute book could be successfully searched for a sentence of
equal length which is of more fuliginous obscurity. --MacKinnon LJ, 1940

Re: Mechanism to provide tai-utc.dat locally

[John Cowan]

Zefram scripsit:

> In the general case: to determine or use an interval of N calendar FOOs,
> it is convenient to represent the time as a linear count of calendar
> FOOs plus details of the exact position within the current FOO.  FOO may
> be minute, hour, day, week, month, or year.  I think there should be
> record formats for all of these cases (the native UTC format is one
> of these with FOO = day), with conversion functions between them and
> also a linear count of seconds.

That's overkill.  If we confine ourselves to the Gregorian calendar,
a time interval can be safely represented as a triple of months,
minutes, and seconds.  All time units longer than a month contain
a fixed and integral number of months, and all time units larger
than a minute and smaller than a month contain a fixed and integral
number of minutes.  (If we don't care about leap seconds, shock
horror, we can just use months and seconds.)

--
The man that wanders far[EMAIL PROTECTED]
from the walking tree   http://www.ccil.org/~cowan
--first line of a non-existent poem by: John Cowan

Re: Mechanism to provide tai-utc.dat locally

[John Cowan]

M. Warner Losh scripsit:

> If I was to compute the number of seconds between Jan 1, 2007 0:0:0 and
> Dec 31, 2008 23:59:50, the answer is 63071990 or 63071991 or 63071992.
> We have no way of knowing today how many seconds are in that interval.
> We do know the answer is one of the above.

Technically 63071999 and 63071998 are also possibilities, though
I admit they are unlikely.

--
John Cowan[EMAIL PROTECTED]http://ccil.org/~cowan
This great college [Trinity], of this ancient university [Cambridge],
has seen some strange sights. It has seen Wordsworth drunk and Porson
sober. And here am I, a better poet than Porson, and a better scholar
than Wordsworth, somewhere betwixt and between.  --A.E. Housman

Re: The fine print

[John Cowan]

Rob Seaman scripsit:

> If NIST and USNO, official agencies of the United States government,
> declare time-of-day to be distinct from time interval, who are we to
> disagree?  As the New York State Supreme Court rules in the play:

I should point out that for historical reasons, in New York State the
name "Supreme Court" is applied to the ordinary trial court for civil
and major criminal cases; there are two levels of appellate courts
above it.

--
John Cowan[EMAIL PROTECTED]http://ccil.org/~cowan
   There was an old manSaid with a laugh, "I
 From Peru, whose lim'ricks all  Cut them in half, the pay is
   Look'd like haiku.  He  Much better for two."
 --Emmet O'Brien

Re: ADASS poster on UTC

[John Cowan]

Steve Allen scripsit:

> For most civil purposes time is only relevant to the nearest minute;

An obvious counterexample is taping TV shows: you don't want to miss
the first or last minute (modulo the presence of commercials).
I go to some trouble to keep my VCR synchronized with NTP time
to the nearest second or two.

--
There is no real going back.  Though I      John Cowan
may come to the Shire, it will not seem [EMAIL PROTECTED]
the same; for I shall not be the same.  http://www.ccil.org/~cowan
I am wounded with knife, sting, and tooth,
and a long burden.  Where shall I find rest?   --Frodo

Re: Titan Time

[John Cowan]

Peter Bunclark scripsit:

> MAPS: In general the flybys around T20 are relatively similar. They
> approach over 35degrees latitude, ~135degrees west longitude (moving from
> north to south) and local time is around 2 am.

Bizarre.  So each Titan local day is 24 local hours long, where an hour
is about 57.4 ksec?

My personal mnemonics:  you can be no more than a ksec late for an
appointment in American culture without anyone making a fuss; a Msec is
a reasonable length of time for a single work assignment; a marriage is
doing very well if it lasts a Gsec (mine is at 0.85 Gsec and counting).

--
Take two turkeys, one goose, four   John Cowan
cabbages, but no duck, and mix them http://www.ccil.org/~cowan
together. After one taste, you'll duck  [EMAIL PROTECTED]
soup the rest of your life.
--Groucho

Re: trading amplitude for scheduling

[John Cowan]

Rob Seaman scripsit:

> Third result - even in the absence of lunar braking, leap jumps
> (or equivalent clock adjustments) would remain necessary.

Why is that?

If the SI second were properly tuned to the mean solar day, and the
secular slowing were eliminated, there would be no need to mess about with
the civil time scale, because the random accelerations and decelerations
would cancel out in the long run.  Of course, we'd have to tolerate larger
differences between clock time and terrestrial time, but we'd expect that.

--
We pledge allegiance to the penguin     John Cowan
and to the intellectual property regime [EMAIL PROTECTED]
for which he stands, one world underhttp://www.ccil.org/~cowan
Linux, with free music and open source
software for all.   --Julian Dibbell on Brazil, edited

Re: trading amplitude for scheduling

[John Cowan]

Rob Seaman scripsit:

> Blame for what?  I'm left wondering.  Are we now fretting about
> the distinction between sidereal and solar time again?

I accidentally specified sidereal rather than mean solar days by
using the wording "the Earth rotates".

> A leap hour is just 3600 embargoed leap seconds.

Indeed.  Which is why I am against the AHLP and in favor of letting
the SI seconds tick, allowing UT-TI to get as large as it likes, and
let the nations of the Earth make up the difference by adjusting their
local time offsets.  No, that won't last forever, but neither will any
other scheme -- when we get to the 36-current-hour day, the connection
with solar time will *have* to be broken, unless we have evolved (or
evolved ourselves) to cope with very different sleep-wake cycles.

BTW, are we now in a position to give a reasonable figure for the
mean and standard deviation of the Earth's deceleration, or do
we not have enough data yet?

--
Evolutionary psychology is the theory   John Cowan
that men are nothing but horn-dogs, http://www.ccil.org/~cowan
and that women only want them for their money.  [EMAIL PROTECTED]
--Susan McCarthy (adapted)

Re: trading amplitude for scheduling

[John Cowan]

Rob Seaman scripsit:

> >1) We have leap seconds because the SI second is shorter
> >than 1/86,400 of a mean solar day.

*facepalm*

Post in haste, repent at leisure (I've been going with too little
sleep lately, for reasons unknown...)  I actually do know that
the earth rotates in less than 1 mean solar day.

--
Work hard,      John Cowan
play hard,  [EMAIL PROTECTED]
die young,  http://www.ccil.org/~cowan
rot quickly.

Re: trading amplitude for scheduling

[John Cowan]

Tom Van Baak scripsit:

> In fact, leap seconds are simply due to the earth
> being slow. How it got to be "slow" and whether
> it is "slowing" are another issue.

Let me see if I have this right:

1) We have leap seconds because the Earth rotates more slowly
than once every 86,400 SI seconds.

2) Leap seconds will become more frequent in the future because
the Earth is decelerating.

3) Leap seconds occur irregularly because the Earth's deceleration
is not constant and in fact changes unpredictably.

Right?

--
LEAR: Dost thou call me fool, boy?  John Cowan
FOOL: All thy other titles  http://www.ccil.org/~cowan
 thou hast given away:  [EMAIL PROTECTED]
  That thou wast born with.

Re: PT Barnum was right

[John Cowan]

Rob Seaman scripsit:

> Most troubling would be if two moving platforms are depending on GPS
> units with differing delays, e.g., two airplanes following neighboring
> flight paths.  How far does an airplane move in 2 seconds?  What is
> the minimum separation required by the FAA?

Jetliners travel at about 550 mi/hr, or 246 m/s.  Required horizontal
separation depends on circumstances, but is rarely less than 3 miles =
4828 m.  So if the discrepancy is 2 s, there is a safety factor of
about an order of magnitude.  Good enough.

--
So that's the tune they play on     John Cowan
their fascist banjos, is it?[EMAIL PROTECTED]
--Great-Souled Sam  http://www.ccil.org/~cowan

Re: independence day

[John Cowan]

Rob Seaman scripsit:

> Why precisely, however, do you regret your inference?  If my
> arguments were to be deemed specious, surely that would strengthen
> opposing arguments (or at least remove competing options).

Because I'm not dueling with you, but trying to communicate my point of
view.  I regret, therefore, that I could not find better words
to do so.

("The fact that I was not dueling with [King] Argaven, but attempting
to communicate with him, was itself an incommunicable fact."  --Genly Ai
in Ursula K. Le Guin's _Left Hand of Darkness_)

> >If the U.S. tied its legal time to the ITU, it could untie
> >it in future if that seems like a good idea.
>
> and later in reply to Markus Kuhn:
>
> >"Reader, suppose you were an idiot, and suppose you were a member
> >of Congress; but I repeat myself."   --Mark Twain (1882)
>
> You can't have it both ways.  Either a prudent decision making
> process is being followed, or it ain't.

These are not contradictory.  A good process *could* be followed; my
suspicion is that it won't be.  Despite Torino, I currently trust ITU in
such matters more than I trust the oligarchy in control of my own country.

> 6) A time standard rooted in an ensemble of clocks, on the other
> hand, is subject to the vagaries of happenstance and history (like,
> say, another Napoleon).  What price to ensure 24/7/365/600
> reliability?  (I look forward to your riposte pointing out that the
> metric system emerged from the Reign of Terror :-)

Only in the sense that a revolution is a good time to change standards
of weights and measures (and money, as the U.S. did).

> >What is to prevent the IERS from issuing bogus leap second
> >announcements?
>
> Precisely the constraint that DUT1 < 0.9s.  Precisely the fact that
> UTC is currently tied to an underlying physical phenomena common to all.

A self-imposed constraint, I think.

--
That you can cover for the plentifulJohn Cowan
and often gaping errors, misconstruals, http://www.ccil.org/~cowan
and disinformation in your posts[EMAIL PROTECTED]
through sheer volume -- that is another
misconception.  --Mike to Peter

Re: independence day

[John Cowan]

Markus Kuhn scripsit:

> Prudent members of the U.S. legislative branch who are currently
> drafting revisions of the definition of U.S. national time may want
> to have a close look at the above wording.

"Reader, suppose you were an idiot, and suppose you were a member
of Congress; but I repeat myself."
--Mark Twain (1882)

--
After fixing the Y2K bug in an application: John Cowan
WELCOME TO[EMAIL PROTECTED]
DATE: MONDAK, JANUARK 1, 1900   http://www.ccil.org/~cowan

Re: independence day

[John Cowan]

Rob Seaman scripsit:

> The point is, however, that nothing - absolutely nothing -
> would then protect legal timekeeping in the U.S. or elsewhere from
> the whims of future timekeepers at the ITU.

I regret to state that this remark appears to me no more than
scaremongering.  The laws of the United States are not the
laws of the Medes and the Persians[*], subject to no repeal.
If the U.S. tied its legal time to the ITU, it could untie
it in future if that seems like a good idea.

In any case, changing the legal definition of U.S. time from GMT
to UTC merely regularizes the de facto position, since GMT no
longer has a specific international definition.

> What in practice would stop these individuals
> from leaping the clock forward or backward at will, or from changing
> the rate of UTC, or for that matter from making the clocks run
> backwards?

The fact of being rendered irrelevant, not to say a laughingstock.
What is to prevent the IERS from issuing bogus leap second announcements?

[*] I am not referring here to the Islamic Republic of Iran.

--
LEAR: Dost thou call me fool, boy?  John Cowan
FOOL: All thy other titles  http://www.ccil.org/~cowan
 thou hast given away:  [EMAIL PROTECTED]
  That thou wast born with.

Re: building consensus

[John Cowan]

Poul-Henning Kamp scripsit:

> >Old English had its own set of month names entirely unrelated to
> >the Latin ones: if they had survived, they would have been Afteryule,
> >Solmath 'mud-month', Rethe[math] 'rough-month', Astron [pl. of 'Easter'],
> >Thrimilch 'three-milking', Forelithe, Afterlithe, Wedmath 'weed-month',
> >Halimath 'holy-month', Winterfilth '-filling', Blotmath 'sacrifice-month',
> >Foreyule.  At least some of these are obviously pre-Christian.
>
> They're practically all viking derived.

I think it more likely that the English and Norse forms have a
common proto-Germanic origin.

--
Dream projects long deferred John Cowan <[EMAIL PROTECTED]>
usually bite the wax tadpole.http://www.ccil.org/~cowan
--James Lileks

Re: building consensus

[John Cowan]

Clive D.W. Feather scripsit:

> I don't think John's referring to "Against the Fall of Night" versus
> "The City and the Stars". Rather, at least in the latter, the official
> ("cover") story of Diaspar (sp?) and the Invaders disagrees in many
> aspects with the "true" story as revealed by Vandemar (sp?).

Just so.  My best recollection now is that the moon was destroyed
either by the Empire or directly by Lys because it was approaching the
Earth too closely.  Presumably this reflects a state of affairs *after*
tidal locking, where the Moon's synchronous orbit begins to decay as a
consequence of the solar tides.

I read TCATS first, and recall it much better than ATFON.

--
John Cowan[EMAIL PROTECTED]http://ccil.org/~cowan
Heckler: "Go on, Al, tell 'em all you know.  It won't take long."
Al Smith: "I'll tell 'em all we *both* know.  It won't take any longer."

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> Of course, any old "I, Claudius" fan knows that Augustus was
> originally named Octavius.  Mere coincidence that the eighth child
> would end up naming the eighth month?

Almost certainly.  The eighth month was Sextilis, as July was originally
Quin(c)tilis.

--
John Cowan  [EMAIL PROTECTED]  http://ccil.org/~cowan
In computer science, we stand on each other's feet.
--Brian K. Reid

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> Makes the zero vs. one indexing question of C and FORTRAN programmers
> look sane.  I've pointed people to the whole 7, 8, 9, 10 sequence
> from September to December on those (admittedly rare) occasions when
> the issue has come up.  Presumably other languages agree in usage,
> which would be another indicator of the age of the names of the months.

The English month-names are borrowed from Old French forms that are
direct descendants of the Latin ones, as is the case in all the Romance
languages.  However, some of them have been cleaned up a bit in Modern
English: "April" is closer to Latin "Aprilis" than Middle English
"Av(e)rill", which is directly from Old French (Modern French 'Avril').

Old English had its own set of month names entirely unrelated to
the Latin ones: if they had survived, they would have been Afteryule,
Solmath 'mud-month', Rethe[math] 'rough-month', Astron [pl. of 'Easter'],
Thrimilch 'three-milking', Forelithe, Afterlithe, Wedmath 'weed-month',
Halimath 'holy-month', Winterfilth '-filling', Blotmath 'sacrifice-month',
Foreyule.  At least some of these are obviously pre-Christian.

Modern German uses the Latin-derived names as well, but in 800,
Charlemagne set up a standardized list of native month names.  Many of
these survived in German until the 18th century: Jaenner < Januarius,
Hornung [meaning unknown], Lenzmonat 'spring-', Oster- 'Easter', Wonne-
'grazing', Brach- 'plowing', Heu- 'hay', Ernte- 'harvest', Herbst-
'autumn', Wein- 'wine', Winter- and Christ-, Jul- 'Yule' or Heiligmonat
'holy month'.

Finally, the modern pronunciation of "July", with the accent on the
second syllable, is a 19th-century innovation of unknown origin.

> >The *seven* day week was, but before then the Romans had a rigid
> >*eight* day week.
>
> The latter, of course, persisted all the way into the 1960's, as
> immortalized by the Beatles' song.

And then there's the Gordon Dickson story "Zeepsday", about how Earth
acquires an eighth day to its week; most people sleep through this
day, but a few discover it.  Eventually, it's determined that Earth
time has been "salted" with time borrowed from a different planet;
fortunately, the protagonist is allergic to foreign time, so Zeepsday
makes him itch.  All is set right in the end.

--
Barry gules and argent of seven and six,John Cowan
on a canton azure fifty molets of the second.   [EMAIL PROTECTED]
--blazoning the U.S. flag   http://www.ccil.org/~cowan

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> Does anyone remember if Earth-Moon dynamics plays a
> role in the story?

It's mentioned, yes.  In the cover story, it was used as a final
defense against the Invaders and destroyed by them.  In the true
story, it was destroyed because it constituted a hazard, but I
forget exactly how.

--
One art / There is      John Cowan <[EMAIL PROTECTED]>
No less / No more   http://www.ccil.org/~cowan
All things / To do
With sparks / Galore -- Douglas Hofstadter

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> References for this?  Your explanation makes a lot of sense and I'm
> prepared to be convinced, but have been skeptical of experimental
> design as applied to questions of human behavior since participating
> in studies as a requirement of undergraduate psychology coursework.
> And if this cycle is inferred from the behavior of undergraduates,
> I'm even more skeptical :-)

I think there's some confusion here between the 24.7h period of the
diurnal mammal free-running clock and the 28h artificial cycles that
Nathaniel Kleitman and his student B.H. Richardson tried to put themselves
on over a 33-day period in Mammoth Cave back in 1938.  Richardson was
able to adapt to a 19h awake / 9h asleep cycle, but the much older
Kleitman was not.

The 24.7h result is quite consistent across diurnal mammals kept in
continuous darkness, including humans.   Google for "circadian rhythms"
for lots more detail.

--
John Cowan  [EMAIL PROTECTED]http://ccil.org/~cowan
No man is an island, entire of itself; every man is a piece of the
continent, a part of the main.  If a clod be washed away by the sea,
Europe is the less, as well as if a promontory were, as well as if a
manor of thy friends or of thine own were: any man's death diminishes me,
because I am involved in mankind, and therefore never send to know for
whom the bell tolls; it tolls for thee.  --John Donne

Re: building consensus

[John Cowan]

Poul-Henning Kamp scripsit:

> I belive this was because the year followed the taxation cycle of the
> government whereas the day+month followed the religiously inherited
> tradtion.

Indeed.  For that matter, the start of the U.K. tax year was left alone
when the calendar changed, and is now 6 April (it should be 7 April,
but for whatever reason no adjustment for 1900 was made).

--
We call nothing profound[EMAIL PROTECTED]
that is not wittily expressed.  John Cowan
--Northrop Frye (improved)

Re: building consensus

[John Cowan]

Mark Calabretta scripsit:
> On Mon 2006/06/05 22:04:40 -0400, John Cowan wrote
> in a message to: LEAPSECS@ROM.USNO.NAVY.MIL
>
> >there was no 1845-12-31 in Manila, any more than there was a
>
> As magic tricks go I don't find this one very convincing - I can
> clearly see the rabbits behind your back.

I don't know what you think you see here; I simply recited facts.
Manila did in fact undergo a huge one-time change in time zone.

--
Mark Twain on Cecil Rhodes:John Cowan
I admire him, I freely admit it,   http://www.ccil.org/~cowan
and when his time comes I shall[EMAIL PROTECTED]
buy a piece of the rope for a keepsake.

Re: building consensus

[John Cowan]

Michael Sokolov scripsit:

> Perhaps you meant 2006-04-02T02:30:00?

Yes.

--
With techies, I've generally found      John Cowan
If your arguments lose the first round  http://www.ccil.org/~cowan
Make it rhyme, make it scan [EMAIL PROTECTED]
Then you generally can
Make the same stupid point seem profound!   --Jonathan Robie

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> We wouldn't be having this discussion if the SI unit of time had simply
> been called the "essen" as originally proposed.  Then the distinction
> between these rather different meanings would be obvious and the need
> for an actual time-of-day solution indisputable.  Eventually one second
> will equal 1.5 essens.  What would the suggestion then be for a
> zero fuss, lotta muss "solution"?  (Ein gedankenexperiment,
> don't try this at home, kids.)

As I've said before, eventually the notion that the solar day contains
24h of 60m of 60s will have to be abandoned.  It'll be awfully hard
to maintain when an "hour" involves two human sleep-wake cycles,
out in the limit when the Moon is fully tidally locked and 1 lunar month =
1 solar day = 47 current solar days, more or less.

--
No,  John.  I want formats that are actually   John Cowan
useful, rather than over-featured megaliths that   http://www.ccil.org/~cowan
address all questions by piling on ridiculous  [EMAIL PROTECTED]
internal links in forms which are hideously
over-complex. --Simon St. Laurent on xml-dev

Re: building consensus

[John Cowan]

Mark Calabretta scripsit:

> You will find December 31, 1844 in both timescales.

All your points are correct, but it doesn't change the fact that
there was no 1845-12-31 in Manila, any more than there was a
second labeled 2006-04-02T00:02:30 in New York.

--
Evolutionary psychology is the theory       John Cowan
that men are nothing but horn-dogs, http://www.ccil.org/~cowan
and that women only want them for their money.  [EMAIL PROTECTED]
--Susan McCarthy (adapted)

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> I presume you aren't asserting that standard time clocks can't be
> accurate, but rather distinguishing between standard (timezone)
> time and local mean solar time?

No, I am reflecting the fact that some people define "local civil time"
in such a way as to exclude daylight-saving shifts.

> On the other hand, all I've ever meant by the term "civil time" is
> that time that a well educated civilian sets her clock in order to
> agree with other civilians for civilian purposes.

Good.  That is what I mean also.

> Interesting question:  On similar historical occasions, for instance
> during the transition from "old style" to "new style" dates as the
> Julian calendar gave way to the Gregorian, has the sequence of days
> of the week remained unbroken?  Or rather, have days of the week been
> skipped as well as days of the month?  Surely the Gregorian calendar
> is not just a rule for adding a leap day every four years (except
> sometimes), but also includes the definitions of the twelve months,
> and an initialization of a specific day-of-the-week on whatever date.

During the British transition, at least, the days of the week continued
their accustomed rotation.  I believe this was true of every such
transition as well.  Even while part of Europe was Gregorian and part
Julian, they all agreed on when Sunday was, most fortunately.

> >This was not a calendar transition, but a (drastic) time zone
> >transition involving moving the International Date Line to the east.
>
> Not obvious that there is any difference - kind of a calendrical
> Mach's Principle.

It is precisely the fact that there was no Wednesday in the Philippines
in that final week of 1845 that made it a time-zone rather than a
calendrical transition.

--
John Cowan  [EMAIL PROTECTED]  http://ccil.org/~cowan
If he has seen farther than others,
it is because he is standing on a stack of dwarves.
--Mike Champion, describing Tim Berners-Lee (adapted)

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> One might suggest that the accommodation between civil time and legal
> time is of more interest.

I'm not sure what you mean by "civil time" in this context.  For some
people, civil time is synonymous with standard time; for others, it
means the time shown by accurate clocks in the locality.  I try to
avoid it, therefore.

> The sun certainly came
> up on that day and rose the following day about 24 hours later.

Yes, but the day was labeled 1845-01-01 and the following day
was labeled 1845-01-02.  There was no day labeled 1845-12-31 in
the Philippines.  Consequently, the year 1844 had only 365 days
there, and the last week of 1845 lacked a Wednesday.

This was not a calendar transition, but a (drastic) time zone transition
involving moving the International Date Line to the east.   (The IDL at
sea is a de jure line, but on land it is de facto and dependent on the
local times chosen by the various nations.)

> When they did that, what did they call it?  "The day after December
> 30, 1844?"  "Next Tuesday?"  (Which begs the question, of course.)

They called it "New Year's Day" or "January 1, 1845" (in Spanish).

> In any event, the case you are basically making is that in throwing
> off the yoke of their colonial masters, the Philippines specifically
> chose that their legal time should match their civil time and that
> their civil time should agree with local solar time.

Not at all and by no means.  Rather, it was Spanish America that had
ceased to be part of Spain; the Philippines switched to Asian time
because they were still a colony (and remained a Spanish colony until
1898 and an American one until 1946) and were no longer trading heavily
with the Americas; most of their trade was with the Dutch East Indies
and China, and it was commercially useful to share the same day.

--
Is a chair finely made tragic or comic? Is the  John Cowan
portrait of Mona Lisa good if I desire to see   [EMAIL PROTECTED]
it? Is the bust of Sir Philip Crampton lyrical, http://ccil.org/~cowan
epical or dramatic?  If a man hacking in fury
at a block of wood make there an image of a cow,
is that image a work of art? If not, why not?   --Stephen Dedalus

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> I wouldn't call this an oddity, but rather an interesting and
> elegant, one might even say charming, local custom.  The logic of
> this accommodation between 6:-00 pm clock time and a mean sunset
> demonstrates another weakness in the ALHP, since clock time would
> drift secularly against mean solar time.

Only if Israel never changes its time zone.

I found another spectacular illustration of how massive the difference
between solar and legal time can be.  Before 1845, the time in Manila,
the Philippines, was the same as Acapulco, Mexico, a discrepancy of
9h16m from Manila solar time.  This was a consequence of the Philippines
having been colonized and administered from Spanish America.  Nowadays the
standard time of Acapulco is UTC-6; of Manila, UTC+8.

Q: "What happened in the Philippines on December 31, 1844?"
A: "Nothing.  It never existed."

--
John Cowan  [EMAIL PROTECTED]  http://ccil.org/~cowan
If I have not seen as far as others, it is because giants were standing
on my shoulders.
--Hal Abelson

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> So the calendar is either immutable - or it isn't :-)

The Gregorian calendar is immutable.  Whether it is in use at a certain
place is not.  Local time is on the Gregorian calendar today in the
U.S., but might conceivably be on the Revised Julian or even the Islamic
calendar a century hence.

> The Gregorian calendar succeeded the Julian, just as the Julian
> succeeded what came before.

But not everywhere at the same time, nor entirely.  There are still
versions of Orthodox Christianity that use the Julian calendar, the
decision being one for each autocephalous church within the Orthodox
communion.  To say nothing of Nova Scotia, which was first Gregorian,
then Julian, then Gregorian again.

Historians aren't exactly consistent on the question.  In European
history, dates are Julian or Gregorian depending on the location;
dates in East Asian history seem to be proleptic Gregorian.

(ObOddity:  It seems that in Israel, which is on UTC+3, the legal
day begins at 1800 local time the day before.  This simplifies
the accommodation of Israeli and traditional Jewish law.)

--
After fixing the Y2K bug in an application: John Cowan
WELCOME TO[EMAIL PROTECTED]
DATE: MONDAK, JANUARK 1, 1900   http://www.ccil.org/~cowan

Re: building consensus

[John Cowan]

Zefram scripsit:

> There is the alternate point of view that the calendar in actual civil use
> in a particular locality, changing between different arithmetic calendars
> at different times, constitutes an unpredictable observational calendar.
> Perhaps we need a concept of "calendar zone" analogous to time zone,
> with a calendar zone database to match.

Claus Tøndering's excellent Calendar FAQ contains a first cut at such
a thing in Section 2.2.4.  See
http://www.tondering.dk/claus/cal/node3.html#SECTION00324000
As one would expect, the information is less than 100% reliable, as
sources disagree.

I particularly like this one:

# Sweden has a curious history. Sweden decided to make a gradual change
# from the Julian to the Gregorian calendar. By dropping every leap year
# from 1700 through 1740 the eleven superfluous days would be omitted and
# from 1 Mar 1740 they would be in sync with the Gregorian calendar. (But
# in the meantime they would be in sync with nobody!)
#
# So 1700 (which should have been a leap year in the Julian calendar)
# was not a leap year in Sweden. However, by mistake 1704 and 1708
# became leap years. This left Sweden out of synchronisation with both
# the Julian and the Gregorian world, so they decided to go back to the
# Julian calendar. In order to do this, they inserted an extra day in
# 1712, making that year a double leap year! So in 1712, February had
# 30 days in Sweden.
#
# Later, in 1753, Sweden changed to the Gregorian calendar by dropping
# 11 days like everyone else.

Note that the Islamic calendar is truly observational: a month starts
when an actual human observer makes a lunar observation, and all
Islamic calendars purporting to show the future are merely best-effort
approximations.  This calendar is official in some but not all Muslim
countries, even for civil purposes.

--
My corporate data's a mess! John Cowan
It's all semi-structured, no less.  http://www.ccil.org/~cowan
But I'll be carefree[EMAIL PROTECTED]
Using XSLT
On an XML DBMS.

Re: building consensus

[John Cowan]

Rob Seaman scripsit:

> A schedule and a rule are the same thing, just regarded from
> different historical perspectives.  The "leap day rule" will most
> certainly have to accommodate scheduling changes over the millennia.

Fair enough, but there is a huge difference in practical terms between
a rule that will work for at least the next six centuries and a rule
that will only work for the next six months (i.e. no leap second before
2006-12-31T23:59:59Z).

> On the other hand, I am sure we haven't exhaustively discussed
> possible refinements to the leap second "scheduling algorithm".  (And
> ain't that a rule?)

I thought the whole point was that while we had a rather good prediction
of changes in the tropical year (viz. none), and therefore only have to
dink with the calendar when the current error of about 8.46 seconds/year
accumulates to an uncomfortably large value, there is simply no knowing,
in the current state of our geophysical knowledge, how the wobbly old
boulder in the sky is going to wobble next.

> The biggest difference between leap days and leap seconds is that
> days are quantized.

Can you expound on this remark?

--
They tried to pierce your heart John Cowan
with a Morgul-knife that remains in the http://www.ccil.org/~cowan
wound.  If they had succeeded, you would
become a wraith under the domination of the Dark Lord. --Gandalf

Re: building consensus

[John Cowan]

M. Warner Losh scripsit:

> : The designers of Posix time thought it was more important to preserve
> : the property that dividing the difference between two time_t values
> : by 60, 3600, 86400 would give minutes, hours, days.
>
> That's the one property that Posix time_t does not have.  The
> difference between time_t's that cross a leap second are off by one
> second, and therefore do not start with the right answer to do the
> division...

I expressed myself badly.  My point is that if you have a Posix time_t
representing 11:22:33 UTC on a certain day, and you add 86400 to that
time_t, you will get the Posix representation of 11:22:33 UTC on the
following day, whether a leap second intervenes or not.  This is a valuable
property, many existing programs depended on it, and the authors of the
Posix spec preserved it at the expense of having a distinct representation
for each UTC second.

You may call this position wrong (and I have done so), but it is
unquestionably defensible.

> It would be better to say the number of SI seconds since 1972 rather
> than UTC seconds, I think.

Indeed.

--
They do not preach  John Cowan
  that their God will rouse them[EMAIL PROTECTED]
A little before the nuts work loose.http://www.ccil.org/~cowan
They do not teach
  that His Pity allows them --Rudyard Kipling,
to drop their job when they damn-well choose.   "The Sons of Martha"

Re: building consensus

[John Cowan]

Zefram scripsit:

> >If this means that leap seconds and leap days are analogous, then I
> >suppose so.  If it means something else, I don't understand it.
>
> That's what I meant.  Can you suggest a clearer wording?

"Leap seconds (after 1972) are closely analogous to leap days."

> Being ambiguous between adjacent seconds seems inherently faulty to me.

The designers of Posix time thought it was more important to preserve
the property that dividing the difference between two time_t values
by 60, 3600, 86400 would give minutes, hours, days.

> Are you thinking of linear counts such as POSIX time, where the
> representation is ambiguous?  I was implicitly excluding those, on the
> grounds that they don't count as a "representation".  It's also not
> "linear".

No, it isn't.  But that doesn't mean you *can't* construct a numerical
representation of UTC time: say, the number of UTC seconds since
1972-01-01T00:00:00Z.

> >Unix time (better: Posix time) *is* monotonically nondecreasing,
> >provided you set it with NTP and not by brute force.
>
> Not necessarily.  The Mills kernel model makes the Unix time perform a
> backward step of 1 s during a positive leap second, and does so using
> data supplied by NTP.  I've seen Linux 2.4 perform this step (but during
> a simulated leap second, not a real one) in the course of testing some
> of my timekeeping code.

Quite so; my error.

--
John Cowan  http://ccil.org/~cowan[EMAIL PROTECTED]
There are books that are at once excellent and boring.  Those that at
once leap to the mind are Thoreau's Walden, Emerson's Essays, George
Eliot's Adam Bede, and Landor's Dialogues.  --Somerset Maugham

Re: Precision vs. resolution

[John Cowan]

Rob Seaman scripsit:

> Interesting question.  Perhaps it is the distinction between
> addressability and physical pixels that one encounters on image
> displays and hardcopy devices?  (Still have to posit which is which
> in that case :-)

Thanks to those who responded either publicly or privately.  In summary,
"infinite are the arguments of mages".  Some take resolution to be a
near-synonym for precision, some take it to be a synonym for granularity.
The more definitive the source, the vaguer the definitions.

I should perhaps explain that I was interested in an internal
representation for durations, which I am now representing as a triple of
months, minutes, and seconds (the number of minutes in a month is not
predictable, nor the number of seconds in a minute given leap seconds,
but all other relationships are predictable:  10080 minutes/week, 12
months/year, 100 years/century, etc.)  To this I would add a fourth
nonnegative integer representing "clock resolution units" and wanted to
make sure I had the terminology correct.

Ah well.

--
John Cowan  [EMAIL PROTECTED]  http://ccil.org/~cowan
In the sciences, we are now uniquely privileged to sit side by side
with the giants on whose shoulders we stand.
--Gerald Holton

Re: building consensus

[John Cowan]

M. Warner Losh scripsit:

> In message: <[EMAIL PROTECTED]>
> Rob Seaman <[EMAIL PROTECTED]> writes:
> : Actually, this list is not a "discussion" per se.  If we simplify the
> : positions - just for the sake of argument here - to "leap second yes"
> : and "leap second no", the reality is that the folks pushing the "leap
> : second no" position have never engaged with this list.  There are
> : several doughty people here who happen to have that opinion, but they
> : abide with us mortals outside the time lords' hushed inner sanctum.
>
> What an amaizingly unhelpful and offsensive statement.  I have spent
> much time explaining why leap seconds cause real problems in real
> applications, only to be insulted like this.

I believe you have misread Rob's remark, though I concede that it was
easy to misread.  I believe Rob meant that the people who are pushing
"leap seconds no" in *official* channels are not to be found on this list.
That being so, the "leap seconds yes" folks are unable to challenge them
or persuade them otherwise.

You and I, on the other hand, fall into the "doughty people here" group.

--
Is a chair finely made tragic or comic? Is the  John Cowan
portrait of Mona Lisa good if I desire to see   [EMAIL PROTECTED]
it? Is the bust of Sir Philip Crampton lyrical, http://ccil.org/~cowan
epical or dramatic?  If a man hacking in fury
at a block of wood make there an image of a cow,
is that image a work of art? If not, why not?   --Stephen Dedalus

Re: building consensus

[John Cowan]

Zefram scripsit:

> Readings of UT1 et al are most naturally represented as a real count of
> rotations since some epoch (i.e., as some form of Julian Date).

Such a claim cannot be evaluated without reference to a purpose.

> Because TT, TAI, et al are measures of time unrelated to planetary
> rotation, it is misleading to apply to them the day-based notations
> (such as the sexegesimal time-of-day notation) that are customarily used
> with UT1 et al.

Almost anything *may* be misleading.

> Readings of linear time scales (TT, TAI, et al) are most naturally
> represented as a real count of SI seconds since some epoch.

Such a claim cannot be evaluated without reference to a purpose.

> Post-1972 UTC, counting TAI seconds while maintaining a "day" cycle that
> closely matches the phase of UT1, is directly analogous to calendars
> that count days while maintaining a "year" cycle that closely matches
> the phase of the tropical year.

If this means that leap seconds and leap days are analogous, then I
suppose so.  If it means something else, I don't understand it.

> Readings of UTC cannot be directly represented by a single linear count.

Of course they can be.  The question of what you can do with that
linear count is another matter.

> Unix time, as standardised by POSIX and as commonly implemented, is a
> faulty encoding of UTC.  The fault is that Unix time readings repeat,
> and so are ambiguous, near positive leap seconds.

"Faulty" is a word implying, well, fault.  The no-fault view is that it's
an *ambiguous* encoding.  Whether that is faulty cannot be evaluated
without reference to a purpose.

> Some applications assume that Unix time is monotonically nondecreasing,
> or that timestamps are unambiguous, and so are poorly served by the
> encoding of UTC in Unix time.

Unix time (better: Posix time) *is* monotonically nondecreasing,
provided you set it with NTP and not by brute force.  The point about
ambiguous timestamps is correct.

> Some applications assume that Unix time is a linear scale suitable for
> interval calculations, and so are poorly served by the encoding of any
> form of UT in Unix time.

You should add "to a precision of 1s".  Applications whose precision
requirements are, say, 1 day, don't have a serious problem.

> New applications need a more sophisticated understanding of time than
> is currently standard practice.

Some do, some don't, some couldn't care less.

--
But that, he realized, was a foolishJohn Cowan
thought; as no one knew better than he  [EMAIL PROTECTED]
that the Wall had no other side.http://www.ccil.org/~cowan
--Arthur C. Clarke, "The Wall of Darkness"

Precision vs. resolution

[John Cowan]

Can someone lay out for me exactly what the difference is between
clock precision and clock resolution?  I've read the NTP FAQ and
several other pages but am more confused than ever.

(I do understand the distinction between precision and accuracy:
3.1429493 is \pi precise to 8 significant digits, but accurate
only to 3.)

Thanks.

--
Values of beeta will give rise to dom!  John Cowan
(5th/6th edition 'mv' said this if you triedhttp://www.ccil.org/~cowan
to rename '.' or '..' entries; see  [EMAIL PROTECTED]
http://cm.bell-labs.com/cm/cs/who/dmr/odd.html)

Re: 24:00 versus 00:00

[John Cowan]

Clive D.W. Feather scripsit:

> However, London Underground does print 24:00 on a ticket issued at
> midnight, and in fact continues up to 27:30 (such tickets count as being
> issued on the previous day for validity purposes, and this helps to
> reinforce it).

Airlines in the U.S., where the double-12-hour clock prevails everywhere
except in the military, avoid arrival or departure times of midnight
so that there is no ambiguity about what "12:00 AM Wednesday" means
(is it  or 2400?).

--
We pledge allegiance to the penguin John Cowan
and to the intellectual property regime [EMAIL PROTECTED]
for which he stands, one world underhttp://www.ccil.org/~cowan
Linux, with free music and open source  http://www.ap.org
software for all.   --Julian Dibbell on Brazil, edited

Re: 24:00 versus 00:00

[John Cowan]

Ed Davies scripsit:

> No, it amounts to saying that some days are 24 hours and 1 second
> long.  When you're half a second from the end of such a day you
> are 24 hours, zero minutes and half a second from the start.

I grant that.  Nonetheless, the third-from-last figure in a broken-out
timestamp reflects the hour number, and by your scheme there would be
25 possibilities for its value, just as by the standard scheme there
are 61 possibilities for the second number.

> If you had a 1'6" piece of string you wouldn't say it's a two
> foot piece of string but the second foot is only 152.4 mm long.
> (Well, I think you wouldn't, though I think some politicians
> might.)

No, I wouldn't.  But in labeling every point on the string to a
precision of 1 inch, I would say that there are two possibilities
for the "number of feet", 0 or 1.

--
John Cowan  [EMAIL PROTECTED]  www.ccil.org/~cowan  www.ap.org
If I have seen farther than others, it is because I was standing on
the shoulders of giants.
--Isaac Newton

Re: 24:00 versus 00:00

[John Cowan]

Ed Davies scripsit:

> If only the 24:00 for end of day notation wasn't in the way
> we could look at positive leap seconds as just being the
> result of deeming certain days to be a second longer than
> most and just use 24:00:00.  We wouldn't have to muck with
> the lengths of any of the hours or minutes within that day.

That amounts to saying that some days have 24 hours, whereas others
have 25 hours, 24 of them being 3600 seconds long and the 25th being
1 second long.  IMHO that is worse.

--
John Cowan  www.ccil.org/~cowan  www.ap.org  [EMAIL PROTECTED]
[T]here is a Darwinian explanation for the refusal to accept Darwin.
Given the very pessimistic conclusions about moral purpose to which his
theory drives us, and given the importance of a sense of moral purpose
in helping us cope with life, a refusal to believe Darwin's theory may
have important survival value. --Ian Johnston

Re: An immodest proposal

[John Cowan]

Neal McBurnett scripsit:

> Since TAI can be recovered from UTC, and hosts that use NTP know UTC,
> those hosts can serve any time they want to clients on that host.  I
> see little reason to change the particular timestamps that are used in
> the NTP protocol, an less reason to have two different timestamps
> within NTP, or to require users on ntp-using hosts to switch their
> ntp servers just to get a different timescale.

The advantage of Steve's approach is that only the relevant NTP servers
have to maintain up-to-date DTAI tables; they serve as public conversion
points from the UTC to the TAI regime.  Some mods would be required to
prevent the ntpd from propagating leap second indicators and leap seconds
themselves, as well as to prevent cross-contamination of the existing UTC-based
NTP network.

However, that only provides TAI at the level of time(); someone would need
to provide a userland library to do the right thing as well.

--
John Cowan  <[EMAIL PROTECTED]>
http://www.ap.orghttp://www.ccil.org/~cowan
.e'osai ko sarji la lojban.
Please support Lojban!  http://www.lojban.org

Re: Comparing Time Scales

[John Cowan]

Tim Shepard scripsit:

> A computer system could represent UTC time in a way which also makes
> this clear, for example by a structure or abstract data type which
> includes in it (1) the day number and (2) how-many nanoseconds are we
> into this day.  When executing a leap second insertion, we would get
> all the way up to 86,400,999,999,999 nano seconds in the day before we
> wrapped around that field to zero and incremented the day number (one
> nanosecond later).

How is this really different from using broken-out time and allowing
the seconds field to go up to 60?

Current Posix broken-out time has a field for "DST in effect", which can
be ignored most of the time except during the fall transition hour, when
it is on for the first run from 02:00:00 to 02:59:59 and off for the
second run.

--
My confusion is rapidly waxing  John Cowan
For XML Schema's too taxing:[EMAIL PROTECTED]
I'd use DTDshttp://www.reutershealth.com
If they had local trees --  http://www.ccil.org/~cowan
I think I best switch to RELAX NG.

Re: Accommodating both camps

[John Cowan]

Warner Losh scripsit:

> This is the biggest misunderstanding [...] an hour off of solar time.

I now abbreviate this whole argument with the word "Kashi".
(To reiterate: |LMT-LCT| in Kashi, a city in western China (which has
no DST), is about 3 hours.)

> >But again, giving up leap seconds in UTC is not the same as
> >accepting atomic time as civil time.
>
> Again, I don't quite understand this statement.  Can you elaberate a
> bit on the difference?

I don't think anyone in the plan #2 camp wants to change UTC as such:
some people find it useful.  What we want, I think (or at least what
I want) is to make TI rather than UTC the foundation of legal local time.

--
"Well, I'm back."  --SamJohn Cowan <[EMAIL PROTECTED]>

Re: Accommodating both camps

[John Cowan]

James Maynard scripsit:

> I wonder, though, whether those in the other camp would find it
> acceptable to have the standard time and frequency stations not only
> broadcast UTC and DUT1 (= UT1 - UTC, to 0.1 s resolution), but also to
> broadcast DTAI (= TAI - UTC, 1 s resolution)?

Speaking for myself only, the answer is no.  It's still necessary to
interact with users and other parts of the landscape in local time,
even if it's possible to get the master time sync in TAI.  I agree that a
more widespread distribution of TAI (probably best achieved by providing
better GPS systems that can output raw GPS time as well as UTC) is a
Good Thing.  But it's the complications (both synchronic and diachronic)
of leap seconds in civil time that are the constant irritant.

That is my opinion, and it is further my opinion that leap seconds must
be destroyed: they are a menace to society.

--
Kill Gorgûn!  Kill orc-folk!John Cowan
No other words please Wild Men. [EMAIL PROTECTED]
Drive away bad air and darkness http://www.reutershealth.com
with brig ht iron!  --Ghân-buri-Ghânhttp://www.ccil.org/~cowan

Re: the tail wags the dog

[John Cowan]

Rob Seaman scripsit:

> >The legal time in the US is the mean solar time at a given
> >meridian, as determined by the secretary of commerce
>
> ...and many may have seen Mr. Gutierrez shooting the sun with his
> sextant out on the Mall in front of the A&S Museum :-)
>
> With all the words that have flowed over the spillway, I'm not sure
> the point has been made that a feature of solar time is precisely
> that it can be reliably recovered from observations whenever and
> wherever needed (once you are located with respect to a meridian, of
> course).

I don't understand this.  You can't shoot the mean sun with a sextant,
only the friendly ("apparent", whatever) sun.  So at the very least
you need an analemma.

In any case, the majority of the world has managed to live with the fact
that the day-of-month can no longer be recovered by examining the moon,
although if we were still hunter-gatherers a purely lunar calendar would
make a lot of sense.

--
XQuery Blueberry DOMJohn Cowan
Entity parser dot-com   [EMAIL PROTECTED]
Abstract schemata   http://www.reutershealth.com
XPointer errata http://www.ccil.org/~cowan
Infoset Unicode BOM --Richard Tobin

Re: Risks of change to UTC

[John Cowan]

Clive D.W. Feather scripsit:

> Why not? Greek and Latin, to name two, were spoken that long ago and are
> recognisable today.

Indeed, and they passed through a far tighter bottleneck than anything
likely today.

Not even the most diligently destructive barbarian can
extirpate the written word from a culture wherein the
*minimum* edition of most books is fifteen hundred
copies.  There are simply too many books.
--L. Sprague de Camp, _Lest Darkness Fall_

> And the English of 1000 years ago is still an official language of the
> Netherlands (under the name "Frisian").

Bread, butter, and green cheese / Is good English and good Friese.
Brea, bûter, en griene tsiis / Is goed Ingelsk en goed Frysk.

(That û is u-circumflex, in case of encoding problems.)

--
Long-short-short, long-short-short / Dactyls in dimeter,
Verse form with choriambs / (Masculine rhyme):  [EMAIL PROTECTED]
One sentence (two stanzas) / Hexasyllabically   http://www.reutershealth.com
Challenges poets who / Don't have the time. --robison who's at texas dot net

Re: Risks of change to UTC

[John Cowan]

Rob Seaman scripsit:

> It would be the abandonment of leap seconds that would break UTC.
> Lobbying to base civil time on some underlying timescale distinct
> from UTC would be one thing.  Conspiring to emasculate UTC is quite
> another.

Once we have accomplished the former, I don't give a hoot about the latter.
Keep UTC if you want.

--
John Cowan  [EMAIL PROTECTED]  www.reutershealth.com  www.ccil.org/~cowan
Heckler: "Go on, Al, tell 'em all you know.  It won't take long."
Al Smith: "I'll tell 'em all we *both* know.  It won't take any longer."

Re: Risks of change to UTC

[John Cowan]

M. Warner Losh scripsit:

> 1500 years ago, no one spoke English.  Chances are the people that
> deal with this problem in 1000 or 2000 years won't speak any language
> recognizable to anybody alive today.

Well, actually people did speak English in 500, as historical reconstruction
makes clear, though we have no specimens of English that old.  Certainly
not 21st-century English, of course.

Still, language drift unlike calendar drift is not inevitable, and nobody
knows what effects, if any, the availability of sound recording will have on
language change.

--
The Imperials are decadent, 300 pound   John Cowan <[EMAIL PROTECTED]>
free-range chickens (except they have   http://www.reutershealth.com
teeth, arms instead of wings, and   http://www.ccil.org/~cowan
dinosaurlike tails).--Elyse Grasso

Re: Monsters from the id

[John Cowan]

Rob Seaman scripsit:

> Time is a fundamental element of all that we do.  Surely public
> policy should not be governed by a drab and dystopian vision of
> a fragmented planet scrabbling randomly to keep our disjoint
> clocks aligned.

I agree.  But I don't agree, of course, that the TI-based version
of LCT causes this to happen.

> The simplest - nay, the only - way to keep our clocks synchronized
> one to the other is to keep them all tied to Mother Earth.

Earth is a fine mother but a lousy clock.

--
Dream projects long deferredJohn Cowan <[EMAIL PROTECTED]>
usually bite the wax tadpole.http://www.ccil.org/~cowan
--James Lileks  http://www.reutershealth.com

Re: Risks of change to UTC

[John Cowan]

James Maynard scripsit:

> Small boats, sea water, and electrical systems don't mix very well. The
> damp, salty environment all too often leads to failures of a boat's
> electrical system.  A prudent sailor should not rely for navigation only
> on electrically powered systems like GPS or loran.

Your points are excellent, although it seems to me that a wind-up GPS
receiver is a possibility.

> But if UTC is allowed to drift away from UT1 by eliminating leap
> seconds, celestial navigation fixes will become less and less useful. A
> time error of half an hour in UT1 equates about to 450 NM at the equator.

Navigators are clearly people who would need access to |TI-UT1| along with
astronomers, yes.

--
John Cowan  www.ccil.org/~cowan  www.reutershealth.com  [EMAIL PROTECTED]
Mr. Henry James writes fiction as if it were a painful duty.  --Oscar Wilde

Re: Risks of change to UTC

[John Cowan]

Neal McBurnett scripsit:

> To sum it up, PLEASE don't fundamentally change the DEFINITION of UTC,
> or you risk whole new kinds of confusion.  Hopefully by now the folks
> on this list that don't like leap seconds at least have agreed that
> any change should be to a new time scale like TI, and announced
> decades in advance.

I certainly do, and I hope everyone else who is down-leaps does too.
TI is a good name (you can read it as "TAI - A" where A is a constant
to be decided when the scale is inaugurated).

--
John Cowan  www.ccil.org/~cowan  www.reutershealth.com  [EMAIL PROTECTED]
[T]here is a Darwinian explanation for the refusal to accept Darwin.
Given the very pessimistic conclusions about moral purpose to which his
theory drives us, and given the importance of a sense of moral purpose
in helping us cope with life, a refusal to believe Darwin's theory may
have important survival value. --Ian Johnston

Re: Risks of change to UTC

[John Cowan]

Rob Seaman scripsit:

> Only a minority (small minority, one would think) of
> systems currently include any DUT1 correction at all - although these
> will perhaps tend to be the most safety-critical applications.  [...]
>
> That is, of course, one of the major issues for astronomers - we rely
> on UTC providing a 0.9s approximation to UT1 and most of our systems
> don't use DUT1.  Even our high precision applications (in either
> interval or universal time) don't tend to require conversions other
> than as a preprocessing step.  Remediating our systems for such a
> fundamental change to UTC would involve much larger changes than Y2K
> did - algorithms and data structures would have to change, not just
> the width of some string fields and sprinkling some 1900's around.

I don't understand this.  The first class of applications, those
that actually receive DUT1 from somewhere, probably have a hard-coded
assumption that |DUT1| never exceeds 0.9s or at worst 1.0s.  They would
need remediation.  The second class, which just assumes UTC = UT1
and doesn't care about subsecond precision, would simply need to be
front-ended with a routine that got DUT1 from somewhere and mixed it
with TI to generate their own UT1.  This is technically remediation,
but of a rather black-box kind.

> Also, standalone applications would have to become network aware to
> have access to externally derived tables of DUT1.

Well, this is perhaps no worse than systems that now have access to UTC
and want reliable interval time needing externally derived tables of
leap seconds.

> Astronomers might be unusual in needing to introduce DUT1 into our
> systems (on a short schedule for a large expense) should Sauron win
> and the nature of UTC change, but we wouldn't be alone.  And as clock
> time diverges further and further from solar time, more systems in
> more communities (transportation, GIS, innumerable scientific
> disciplines, what have you) would be revealed to need remediation.

Can you spell out some of those implications?

--
What has four pairs of pants, lives John Cowan
in Philadelphia, and it never rains http://www.reutershealth.com
but it pours?   [EMAIL PROTECTED]
--Rufus T. Firefly  http://www.ccil.org/~cowan

Re: Monsters from the id

[John Cowan]

Rob Seaman scripsit:

> I just continue to enjoy the fact that folks
> with completely opposite points of view about civil timekeeping have
> the same low opinion about leap hours :-)

Feel free to adopt the acronym "ALHP".

> ...and Algeria had the freedom to do so precisely because UTC existed
> to function as a worldwide civil timescale that continued
> uninterrupted "in the background" while the local authorities
> extemporized.  Presumably you would assert that TI (TAI + constant)
> could serve this same purpose.

Indeed.

> I disagree that interval time can indefinitely serve
> as a stand-in for solar time.  It is when the first leap hour (or
> timezone migration event) occurs that interval time fails the test.
> And precisely because it is a timescale that is designed to simply
> tick, tick, tick in even intervals.

I agree wrt leap hours, but why wrt timezone migrations?  TI ticks
steadily, local time jumps about as local requirements demand;
both agree on the size of the second.  This will break down when
timezone migrations occur too often, but then we will have to do
something else altogether.

> >By the way, I re-counted all the secular time zone transitions
> >worldwide.  According to the Olson timezone database, there have
> >been 516 of them since the beginning of standard time (when that
> >is, of course, varies with the country or subdivision thereof).
>
> I think we're using the word "secular" in different ways:

Yeah, we went through this before, and I'm abusing "secular" to mean
"aperiodic".  Excluding DST transitions, there are 516 timezone
changes in the Olson files.  Some of these are really duplicates
because the Olson data merges zones that have had the same history
since 1970, but only if they are currently in the same country;
currently separate countries are always treated separately.

--
John Cowan  www.ccil.org/~cowan  www.reutershealth.com  [EMAIL PROTECTED]
All "isms" should be "wasms".   --Abbie

Re: Monsters from the id

[John Cowan]

Mark Calabretta scripsit:

> If you go through the exercise trying to tie leap hours to DST, as I
> challenged, you will discover that it raises many questions that are not
> addressed by the leap hour proposal.

I realize the ALHP has severe problems with this, but I don't approve
of the ALHP anyhow (save perhaps tactically, as explained).

> If you make some plausible assumptions as to how it would operate, with
> DST starting and ending at the usual times of year and leap hours
> occurring on new year's eve, I believe you will find it far from simple
> to do in a rigorous fashion, and that at least one of the timescales is
> genuinely discontinuous.

Indeed.  But the sensible approach would be for each State government to
fail to omit the hour of the normal spring transition in the year 2700,
say.  In that way, AEDT would become TI+1000 and a normal-looking autumn
transition would cause AEST to become TI+0900.  Countries without DST
transitions would have to actually repeat an hour, of course, just
as Algeria had to do in 1940, 1956, 1977, and 1981 (the country has
repeatedly flipflopped between UTC+ and UTC+0100).

By the way, I re-counted all the secular time zone transitions worldwide.
According to the Olson timezone database, there have been 516 of them
since the beginning of standard time (when that is, of course, varies
with the country or subdivision thereof).

--
John Cowan  http://www.ccil.org/~cowan  [EMAIL PROTECTED]
Be yourself.  Especially do not feign a working knowledge of RDF where
no such knowledge exists.  Neither be cynical about RELAX NG; for in
the face of all aridity and disenchantment in the world of markup,
James Clark is as perennial as the grass.  --DeXiderata, Sean McGrath

Re: Problems with GLONASS Raw Receiver Data at Start of New Year

[John Cowan]

Rob Seaman scripsit:

> I haven't been able to decipher what the humor is meant to be here -
> will gladly admit that this is likely a failure on my part.  I won't
> ask you to explain the joke, but rather I suspect you had a more
> basic point you were seeking to make.  Is there some reason that
> risks resulting from a diverging DUT1 can be expected to be mitigated
> (even in part) as it grows past 1s?

There are a lot of systems, it seems, that assume DUT1 is bounded by
either 0.9s or 1s.  If leap seconds are turned off, then I'd expect that
these will break and be replaced by systems that assume DUT1 is unbounded.

--
John Cowan  [EMAIL PROTECTED]  www.reutershealth.com  www.ccil.org/~cowan
No man is an island, entire of itself; every man is a piece of the
continent, a part of the main.  If a clod be washed away by the sea,
Europe is the less, as well as if a promontory were, as well as if a
manor of thy friends or of thine own were: any man's death diminishes me,
because I am involved in mankind, and therefore never send to know for
whom the bell tolls; it tolls for thee.  --John Donne

Re: Problems with GLONASS Raw Receiver Data at Start of New Year

[John Cowan]

Rob Seaman scripsit:

> But there are also risks associated with *not* having
> leap seconds, with allowing DUT1 to increase beyond 0.9s, for
> instance.  And events triggered by those risks would not draw
> worldwide scrutiny - they could occur year-round and the media circus
> would have moved on.

I'd expect to see a wave of breakage as DUT1 exceeded 0.9s for the first
time, and a second wave as it exceeded 1s for the first time.  After
that, of course, the problems would no longer be relevant.  :-)

--
They tried to pierce your heart     John Cowan
with a Morgul-knife that remains in the http://www.ccil.org/~cowan
wound.  If they had succeeded, you wouldhttp://www.reutershealth.com
become a wraith under the domination of the Dark Lord. --Gandalf

Re: Monsters from the id

[John Cowan]

Mark Calabretta scripsit:

> The situation with the proposed leap hour is quite different.  Given
> that AEST is defined as UTC+1000, and AEDT as UTC+1100, would someone
> care to speculate, in terms similar to the above, what will happen when
> a leap hour is inserted?

Perhaps the two scales will be labeled O.S. and N.S., as our anglophone
antecessors did when switching from Julian to Gregorian.

--
John Cowan  [EMAIL PROTECTED]  www.reutershealth.com  www.ccil.org/~cowan
This great college [Trinity], of this ancient university [Cambridge],
has seen some strange sights. It has seen Wordsworth drunk and Porson
sober. And here am I, a better poet than Porson, and a better scholar
than Wordsworth, somewhere betwixt and between.  --A.E. Housman

Re: Monsters from the id

[John Cowan]

Rob Seaman scripsit:

> And the point I'm making is that you can't shift timezones at will to
> accomplish this without creating seams in legally realized time.

We already have seams in legally recognized time.

> Just making the dark "stay put" would result in ambiguous
> timekeeping.  Daylight saving time layered on solar locked standard
> time is a different thing from attempting to use an overtly similar
> mechanism to compensate for the misappropriate substitution of
> interval time for solar time.

Stripped of the adjectives, why is it different?

> What starts out as "gradual" (also known as "ignored completely")
> will end in the same familiar quadratic rush.  Nothing about your
> notion mitigates this.

In the end, it will be impossible to maintain the notion that a solar
day is 24h of 60m of 60s each: we wind up, IIRC, with the solar day
and lunar month both at about 47 current solar days.

> 1) provide a system for uniquely sequencing historical events

Haven't got that now.

> 2) allow events in distant lands to be compared for simultaneity

We have that now, but it takes a computer to keep track of all the
details in the general case.

> 3) avoid disputes over contractual obligations

That's done by specifying the legal time of a given place.  If I agree
to meet you under the Waverley at noon 13 March 2020, it's all
about what the U.S. Congress says legal time in New York City is
as of that date -- which is not predictable in advance.  (You will also
have a problem finding the Waverley, unless you are an old New Yorker.)

> 4) minimize the potential for political disagreements

Good luck.

> 5) satisfy religious requirements

Out of scope.

> 6) keep it dark near 00:00 and light near 12:00

Agreed.

> 7) support educational goals ("Yes Virginia, the universe actually
> makes sense.")

No problem.

> 8) allow coal miners to aspire to be amateur astronomers

Eh?  I am not recommending abolishing UT1, though it seems strange to
me to measure angles in hours, minutes, and seconds instead of in
radians like a proper SI-head.  ("Fourteen inches to the pound, oh Bog!")

> 9) permit the construction of sundials - public clocks with no moving
> parts

Sundials don't show legal time or even a good approximation of it much
of the time.

> 10) tie an individual's first breathe on her first day to her last
> breathe on her last day

Where's the problem here?  Any timescale can do that, even the Mayan Long Count.

--
John Cowan  [EMAIL PROTECTED]  www.reutershealth.com  www.ccil.org/~cowan
The whole of Gaul is quartered into three halves.
-- Julius Caesar

Re: Monsters from the id

[John Cowan]

Rob Seaman scripsit:

> I went rummaging through the ITU proposal and back as far as Torino.
> Found this comment from a LEAPSECS thread on 28 July 2003:
>
> >>> At Torino the proponents of omitting leap seconds supposed that the
> >>> governments of the world might handle this situation using leap hours
> >>> introduced into civil time by occasionally omitting the annual ``spring
> >>> forward'' change to jump to summer/daylight time.

This is definitely the PHK/JWC proposal rather than the ALHP: "civil time"
refers to local legal/business time.

> >>The difference of UT1 from UTC should not exceed ±1h.

This, however, clearly is the ALHP.

> The point I was trying to make is that you can't simultaneously omit
> the overlaps/gaps and preserve anything even vaguely resembling the
> familiar relationship between our clocks and the solar day.

The relationship between our clocks (legal time clocks, the only kind
I am concerned with) and the solar day is very weak, as I have established
over and over.  If local  is the middle of the night, the practical
requirements of legal time are pretty much satisfied.

> people everywhere in the world
> would  have to deal with the repercussions.  That the situation will
> degrade slowly over a few hundred years before collapsing
> catastrophically doesn't really seem to recommend the plan.

There will be no catastrophic collapse, just a gradual local adjustment
as needed.

> It may not sound like it, but I am willing to be convinced otherwise
> - but you'll have to do a lot better than rivaling the scant length
> of the ITU proposal.  How about a detailed scenario of exactly how
> you see this working for a couple of neighboring but distinct local
> timezones?  What is the precise mechanism that might be used?

A sovereign country will notice that there is too much discrepancy
between solar time and legal time to be comfortable: perhaps kids are
waiting for school buses in the dark, as happened in the U.S. in 1974.
The country will then adjust its legal time, perhaps in coordination
with its neighbors, perhaps not.

> The subtext of both your position and the "absurd leap hour proposal"
> is that civil timekeeping is so trivial that everybody from barbers
> to burghermeisters should be encouraged to make public policy - after
> all, these aren't "important" scientific and technical issues.

Those who want UT1 or TAI know where to get it.

> Rather, civilian users deserve as good or better a timescale as the
> technical users (who ultimately can take care of themselves).

Good for what?  (This is not a rhetorical question.)

> Aliens?  Us?  Is this one of your Earth jokes?

No.

--
John Cowan  [EMAIL PROTECTED]  www.reutershealth.com  www.ccil.org/~cowan
The known is finite, the unknown infinite; intellectually we stand
on an islet in the midst of an illimitable ocean of inexplicability.
Our business in every generation is to reclaim a little more land,
to add something to the extent and the solidity of our possessions.
--Thomas Henry Huxley

Re: War of the Worlds

[John Cowan]

Neal McBurnett scripsit:

> > I wouldn't be too quick to dismiss tidal braking from Phobos.  It's
> > awfully close to Mars, and tidal braking is as you say an inverse-cube
> > effect.  The formula (kai Wikipedia) is (2GMmr)/R^3, where M and m are
> > the masses, r is the radius of the primary, and R is the orbital radius
> > of the secondary.  The mass of the Earth-Moon system is eight orders of
> > magnitude larger than the Mars-Phobos system, and the radius of Earth
>
> I assume you mean the mass of phobos vs the mass of the moon, not the
> systems, since that is what fits in the raw numbers and equations you
> provide.  But that is less than 7 orders of magnitude different, as I
> read your reference.

Actually I didn't mean either one: I meant the mass of the primary times
(not plus) the mass of the secondary, the "Mm" in the formula.  So
the mass of Mars times the mass of the Phobos is ~ 10^39 kg, whereas
the mass of Earth times the mass of the Moon is ~ 10^47 kg:  eight
orders of magnitude, as I said.  Sorry for the misstatement.

--
Even a refrigerator can conform to the XML  John Cowan
Infoset, as long as it has a door sticker   [EMAIL PROTECTED]
saying "No information items inside".   http://www.reutershealth.com
--Eve Maler http://www.ccil.org/~cowan

Re: Monsters from the id

[John Cowan]

Rob Seaman scripsit:

> Folks have been tossing around the notion of aligning this with daylight
> saving time - but DST in what locality?  Does anyone really believe that
> a leap hour would be introduced on different calendar dates worldwide?
> (It seems to me that the one time it is guaranteed NOT to occur is
> during a daylight saving transition.)

No one, at least not on this list, is arguing for an alignment of the
absurd leap hour proposal (henceforth ALHP) with DST changes.  What PHK
and I are arguing for is this:

1)  the abandonment of UTC as the worldwide base from which local
time is set in favor of TAI (minus some constant offset); and

2)  the recognition of the right of local jurisdictions to alleviate
any practical difficulties of this change by changing their offset
from TAI from one value to another.  (I speak of recognition
because of course sovereign jurisdictions can already change
their offsets for any reason or no reason.)

This has nothing whatever to do with inserting leap hours into UTC,
except in the sense that it might be tactically sensible to support the
ALHP in the expectation that no such leap hour would ever be introduced.

> Not satisfied with the ITU position that UTC should merely be
> emasculated to correspond to TAI - 33s - Nx3600s (which, of course,
> really has the effect of ensuring that TAI itself will remain a
> completely irrelevant mystery to the public), some would completely
> eliminate UTC from the equation (or is it that they would eliminate
> TAI?)

It is UTC that would be eliminated as the basis for local time.  It could
be maintained for such other purposes as anyone might have.

> But under this interpretation we're to believe that the very notion
> of international civil time is anathema (except perhaps for TAI with
> some oddball persistent 33s offset and either a one hour gap or one
> hour repetition every few hundred years).  What this means is that
> *local* civil/business/legal time contains this gap or this
> repetition.  I suspect we can agree that the civilians/
> businesspersons/lawyers won't care whether the issue is local or not,
> all they are going to see is a repeated time sequence or a gap - and
> with no possibility of appeal to standard time, because standard time
> as we know it simply won't exist anymore.

We already have that repeated time sequence and gap in much of the world,
and live with it.  These repetitions would be no better and no worse;
when a gap is present, the local sovereignty can omit the gap, but this
is not a necessary feature of the proposal.

> And historical time?  Well, historians will simply have to get with
> the program.  Suck it up.  Perhaps loudspeakers will announce the
> arrival of the leap hour (or leap timezone migration event) with the
> admonition to refrain from historically significant activity for the
> space of one hour.

Historians already deal with the discontinuity between Julian and
Gregorian calendars, which was similarly conducted in a decentralized
fashion between 1582 and 1924.  And that's to say nothing of Sweden,
which made 1700 a non-leap year (thus using a non-Julian, non-Gregorian
calendar as of March 1) and 1712 a double leap year (reverting to the
Julian calendar after February 30), switching finally to the Gregorian
calendar in 1753.

Worst of all, Nova Scotia was settled by the French in 1605 and put on
the Gregorian calendar, and then switched to Julian with the British
conquest in 1710 so that the dates October 2-13 were *doubled up*,
first as Gregorian, then as Julian.  Eventually, it switched back to
Gregorian in 1752 with the rest of the British Empire.  (Grotty details
at http://www.tondering.dk/claus/cal/node3.html .)

--
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with a Morgul-knife that remains in the http://www.ccil.org/~cowan
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become a wraith under the domination of the Dark Lord. --Gandalf

Re: War of the Worlds

[John Cowan]

Rob Seaman scripsit:

> I don't have an envelope large enough, but there are various issues
> to consider.  The Hurtling Moons of Barsoom are much smaller than our
> own and should have a negligible tidal breaking effect.  (See http://
> www.freemars.org/mars/marssys.html, for instance, for their
> interesting history.)  And do the Earth's oceans mediate our Moon's
> breaking or is that a crustal phenomenon?  (The Earth-Moon system
> should better be regarded as a double planet, than planet and
> satellite.)  On the other hand, Mars passes much closer to Jupiter,
> the 800 pound gorilla of the solar system, but then it is further
> from King Kong - the Sun, that is - and tides are an inverse cube
> effect.  But Mars is much smaller and has a smaller moment of inertia
> in the first place - but then Mars is much smaller and the "lever
> arm" to grapple with it is less pronounced.
>
> Taken all together, one suspects that LOD(Mars) is many orders of
> magnitude more constant than LOD(Earth).  One would not be
> flabbergasted to be utterly wrong, however.

I wouldn't be too quick to dismiss tidal braking from Phobos.  It's
awfully close to Mars, and tidal braking is as you say an inverse-cube
effect.  The formula (kai Wikipedia) is (2GMmr)/R^3, where M and m are
the masses, r is the radius of the primary, and R is the orbital radius
of the secondary.  The mass of the Earth-Moon system is eight orders of
magnitude larger than the Mars-Phobos system, and the radius of Earth
is only twice the radius of Mars, but the ratio of the cubed orbital
radii is five orders larger for Phobos than for the Moon.  So the tidal
acceleration of the Moon toward the Earth is only some three orders larger
than Phobos's toward Mars.  That puts the effect in the same ballpark.
How much difference in actual slowing can be attributed to Earth's ocean
and Mars's lack of one I don't know.

(See http://www.madsci.org/posts/archives/oct98/908453811.As.r.html for
the relevant masses and radii.)

--
Eric Raymond is the Margaret Mead   John Cowan
of the Open Source movement.[EMAIL PROTECTED]
--Bruce Perens, http://www.ccil.org/~cowan
  some years agohttp://www.reutershealth.com

Re: The real problem with leap seconds

[John Cowan]

Tim Shepard scripsit:

[many sensible opinions snipped]

> "leap hours" are a horrible idea, whether they be leap hours inserted
> in to some UTC-like global standard, or by local jurisdictions.

I understand what's wrong with the former kind, but what's wrong with
the latter?  Why do you think they are more of a problem than DST shifts?

--
Andrew Watt on Microsoft:   John Cowan
Never in the field of human  computing  [EMAIL PROTECTED]
has so much been paid by so manyhttp://www.ccil.org/~cowan
to so few! (pace Winston Churchill) http://www.reutershealth.com

Re: interoperability

[John Cowan]

Rob Seaman scripsit:

> >This is like the "day is light and night is dark" statement: there
> >is, at any given location, one and only one sunrise per (solar)
> >day, no matter what clocks say.
>
> Communication prospers when people's clear meaning is not subjugated
> to petty grammarians.

My point was that your rhetorical flourishes have run away with you
on more than one occasion.

> We are now - and have been - discussing timekeeping changes that call
> into question the definition of a "day".  Those of us who support
> solar time are fundamentally asserting the primacy of the the
> standard day over the standard second (for civil timekeeping
> purposes).  Those of us who consider solar time to be a curious
> anachronism, assert the the SI second over the concept of a day (for
> civil timekeeping purposes).

I agree with this assessment, more or less.

> >As I've pointed out before, future times in legal documents are
> >defined as LCT for a particular place, since the future mapping
> >between LCT and any other time scale is not known.
>
> At the risk of igniting a new round of "stage two" nonsense, consider
> the implications of your statement.  Currently LCT (as you appear to
> mean it) is standard time.  Daylight saving (under whatever name) is
> merely an overlay on standard time.  Standard time has no jumps
> (except for leap seconds).
>
> Under your suggestion, LCT would include the jumps for daylight
> saving time (if locally used) as well as the jumps to correct for the
> cumulative effect of tidal slowing.  As I hope I have established,
> these are "fall back" discontinuities that would result in the same
> hour of LCT occurring twice.  Is this not perceived to be a problem?

Perhaps the problem here *is* merely semantic.  By LCT I mean legal
time, the time that de jure or de facto is observed in any given place
(New York time in New York, Podunk time in Podunk, and Squeedunk time
in Squeedunk).  That includes all periodic or secular changes.
And although periodic changes are far more common, secular changes
for reasons of public convenience are *far* from unknown.

I will try to say "legal time" from now on, though there are parts of
the world (Antarctica, the oceans) where there is no legal time
strictly speaking, and de facto time rules.

It *is* a problem that some instants of (TAI/UTC) time have the same
LCT labels in certain time zones.  But it's a problem that we already
deal with once a year.  TV stations, for example, normally broadcast
the same program twice in a row on Leapback Sunday, at least in the U.S.

--
John Cowan  [EMAIL PROTECTED]  www.ccil.org/~cowan  www.reutershealth.com
The penguin geeks is happy / As under the waves they lark
The closed-source geeks ain't happy / They sad cause they in the dark
But geeks in the dark is lucky / They in for a worser treat
One day when the Borg go belly-up / Guess who wind up on the street.

Re: interoperability

[John Cowan]

Poul-Henning Kamp scripsit:

> Windows have got it right now I belive, but it used to be that a
> file created and transmitted from Denmark at the end of the business
> day would be older than a file created at the start of business day
> in California, despite a strict ordering of the events.

It's still true in the sense that the hardware clock is assumed to run
in LCT on Windows, and therefore discovering UTC depends on a correctly
set TZ variable.  It's false in the sense that Windows now supports TZ
correctly.

> Sure, and you can timestamp then on either timescale, because there
> is a 1 to 1 translation between the two timescales [1].

I think it's confusing to call it "1 to 1", except in the sense that
LCT seconds are the same length as UTC/TAI seconds.  There are many
LCT timestamps that correspond to more than one UTC timestamp.
This can be kludged around by adding a bit (the isdst field in a struct time)
to say whether a LCT timestamp is the first or the second instance.

> The scheme you propose is eminently workable, and more or less exactly
> what we advocate.  I'm happy that you now see the merits of it.

Nope, he still doesn't.

--
On the Semantic Web, it's too hard to prove John Cowan[EMAIL PROTECTED]
you're not a dog.  --Bill de hOra   http://www.ccil.org/~cowan

Re: interoperability

[John Cowan]

Rob Seaman scripsit:

> >Sure, and you can timestamp then on either timescale, because there
> >is a 1 to 1 translation between the two timescales [1].
>
> Perhaps I miss your meaning here, too.  The event of migrating a time
> zone is a discontinuity just as with a leap second or leap hour.

Sure.  But discontinuities in LCTs are something we already know how to handle.

> This is true.  It is irrelevant to the underlying international
> clock.

PHK and I are denying any need for an international clock that tracks
Earth rotation.

> What matters is not when sunrise occurs, but rather that every day
> has one (and only one).

This is like the "day is light and night is dark" statement: there is,
at any given location, one and only one sunrise per (solar) day,
no matter what clocks say.

> Exactly.  The pressures to maintain a common international vision of
> time will trump local variations.  It is the resulting common
> international  time clock that you won't let me refer to as "civil
> time".  All requirements placed on UTC flow backwards from here.  You
> can't just edit UTC (or GMT) out of the debate.

What common international vision of time?  There is no common international
LCT.

>stage one is atomic time (e.g., TAI)
>stage two is international civil time (e.g., UTC)
>stage three is local legal time (e.g., Mountain Standard Time)

What we are looking for is to redefine stage three directly in terms of
stage one without regard to a factitious stage two.

> >In a couple of hundred years, the Danish Parliament (or its
> >successor in interest) will simply decide "from -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.

Exactly!  That is what the principle of subsidiarity demands, and it is
a situation we already know how to handle.

> A fall back event means that the clock (local, standard,
> international, whatever clock you want) first traverses an hour - and
> then traverses it again.  Under the current three stage system it is
> only the most local stage three clocks that are affected.  You are,
> in effect, promoting this discontinuity to stage two - to the
> worldwide business timescale.  More to the point, you have said that
> stage one can be mapped back-and-forth to stage two.  But we've just
> shown that this is no longer a one-to-one mapping since the hour is
> traversed twice, corresponding to two hours of TAI duration.

You've redefined stage two in the course of this discussion.  Before it
meant LCT, now it means UTC.  But be that as it may.

Since we (PHK and I) are in favor of abolishing stage two, we are not
promoting the discontinuity from stage three to stage two.  Rather, we are
interested in allowing the various local authorities to introduce changes
into their stage three clocks *as they decide* to deal with any perceived
problems.

The "true leap hour" folks, if any, are actually doing what you say we are
doing: creating a large discontinuity in stage two.  The "fake leap hour"
folks, if any, are actually doing what we want, but are cynically saying
there will be a leap hour in stage two while not expecting such a thing
to ever happen.

> Ah!  But you've suggested that the other half of the annual daylight
> saving pendulum be used.  This doesn't work because we're on the
> wrong side of the pendulum's arc.  The point being that you don't
> need to *not* adjust the clock in the Autumn - you need to not adjust
> the clock in the Spring.  It is the springtime "gap" in the mapping
> (also not a very desirable feature for a time scale) that is omitted
> during one of these events - not the harvest-time doubly traversed hour.

Fair enough.

> (We'll omit discussion of the fact that not all localities observe
> daylight saving time in the first place.)

By all means.  (This is the rhetorical figure of *praeteritio*.)

> This is the same point I was trying to make about the 25 hour day.
> No historian or lawyer is going to look favorably on a situation that
> results in ambiguous timestamps.  Perhaps, you say, such timestamps
> should all be kept in TAI.  But in that case, we are back to the
> original question of why a stage two clock is needed at all.  By
> asserting stage two is needed, all the rest logically follows.

And we assert that stage two is *not* needed.  In any case, most of the
world's population deals with ambiguous timestamps every

Re: interoperability

[John Cowan]

Rob Seaman scripsit:

> The question is:  how precisely does this differ from the situation
> now or in the past?  Whether by fiat or not, some common worldwide
> "stage two" clock must exist.

Again, no it doesn't need to exist.

We need a uniform time scale like TAI.  And we need local civil time
for all the 400-odd jurisdictions in the world today.  If other people
need other timescales (and they do), there's no reason that should
affect the two requirements above.

> But how in practice is it envisaged that a scheme
> for migrating time zones versus TAI would work, precisely?

Straightforwardly.  Each locality decides when and how to adjust both
its offset from TAI and its seasonal transition function (if any),
just as it does today.  What we abandon is a universal time tightly
synchronized to Earth rotation in favor of a universal time
independent of earth rotation plus 400+ local civil times roughly
synchronized to Earth rotation containing various glitches.

--
We pledge allegiance to the penguin John Cowan
and to the intellectual property regime [EMAIL PROTECTED]
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Linux, with free music and open source  http://www.reutershealth.com
software for all.   --Julian Dibbell on Brazil, edited

Re: The opportunity of leap seconds

[John Cowan]

Poul-Henning Kamp scripsit:

> >By your logic, the U.S. Surgeon General should be a chiropractor.
>
> Once the US government tries to shoulder their national deficit
> that would undoubtedly be a good idea.

Chiropractors are by no means cheaper to hire than other doctors.
Nor are their treatments necessarily the worse because their theory
is crappy.

> Light of day and darkness of night already is, and for all relevant
> future can be, assured by governmental adjustments of the two functions
> government control in the formula:
>
> Civil Time(time) = UTC(time) +
>  TimeZoneOffset(country, subdivision, time) +
>  SeasonalOffset(country, subdivision, time)

Indeed.  I did a quick look once at the number of secular changes to the
TimeZoneOffset function since the adoption of standard time in the
various countries; I may have posted the results here.  If not,
I'll try to dig them up.

--
John Cowan  [EMAIL PROTECTED]  www.reutershealth.com  www.ccil.org/~cowan
   There was an old manSaid with a laugh, "I
 From Peru, whose lim'ricks all  Cut them in half, the pay is
   Look'd like haiku.  He  Much better for two."
 --Emmet O'Brien

Re: The real problem with leap seconds

[John Cowan]

Steve Allen scripsit:

> The changes in the length of any kind of year are slight by comparison
> to the changes in length of day.  Neglecting "short" period variations
> the length of the sidereal year has not changed much in a billion years.

That is to say, the current best approximation to the n-body problem of
the Solar System says that it hasn't.  Fair enough.  I merely threw that in
in case it was an issue.

> The Gregorian calendar was designed to match the "vernal equinox year".

Thanks for the correction.

> The new fields being added to GPS signals make them able to count leap
> seconds for 3 years.  That's quite an example of engineering margin.

Indeed.  But then so is IPv6 (if we ever get it adopted widely).

--
John Cowan  [EMAIL PROTECTED]  www.ccil.org/~cowan  www.reutershealth.com
In the sciences, we are now uniquely privileged to sit side by side
with the giants on whose shoulders we stand.
--Gerald Holton

Re: The opportunity of leap seconds

[John Cowan]

Rob Seaman scripsit:

> Unless we *completely* change our notion of Canoli, Canoli is tightly
> constrained to follow Eclair simply by the fact that today and
> tomorrow and the million days that follow are all required to be dark
> at night and light in the day.

I think you are getting carried away by your own rhetoric here.  It will
be dark at night and light in the daytime even if we smash every clock
on Earth (not a bad idea, I think sometimes).  What you surely mean
is that it should be locally dark when local clocks say  and thereabouts,
and consequently light when they say 1200 and thereabouts.  There is
much room for adjustment around the midpoints, however.

> Whether we choose to bleed off the
> daily accumulating milliseconds one second or 3600 at a time, bleed
> them we must...and even people who loathe the very notion of leap
> seconds admit this.

NO, I DON'T ADMIT THAT.  On the contrary, I deny it, flatly, roundly,
and absolutely.

> (The craven ITU proposal is obligated to pay lip
> service to leap hours, though what they really are saying is "let's
> close our eyes and wish it away".)  Time to move on.

The leap-hour proposal can be read as either (a) a serious proposal to
inject an hour into UTC at some future date, or (b) a cynical proposal to
abandon leap seconds and not replace them.

I think (a) is just as foolish as leap seconds, if not more so.  As for
(b), it may be the best political approximation to what I really want,
which is (c): abandon leap seconds altogether.

"But then, soon enough, it won't be dark at !"  Yes it will, just
not in the skies over Greenwich.  Practical difficulties can be overcome
by making secular changes to the offsets between LCT and UTC, just as is
done today when such problems arise.  (In the next two years, the U.S.,
to name just one country, will make two secular changes to its LCT offsets.)

The computerniks of the world already know how to handle such things,
so future migrations will not be a problem.

And people who want, for their legitimate purposes, to have access to UT1
will have to get it some other way.

--
It was impossible to inveigle   John Cowan <[EMAIL PROTECTED]>
Georg Wilhelm Friedrich Hegel   http://www.ccil.org/~cowan
Into offering the slightest apology http://www.reutershealth.com
For his Phenomenology.  --W. H. Auden, from "People" (1953)

Re: The real problem with leap seconds

[John Cowan]

Ed Davies scripsit:

> (There's a small difference in practice in that the UTC to
> TAI conversion requires a lookup table which is not known
> very far into the future whereas the Gregorian calendar is
> defined algorithmically for all time.)

Well, yes.  But that's a matter of verbal labels.  The Gregorian calendar
extends to all future time: what is not known is the date on which it
will be replaced in civil use by a further refinement.  We know we will
need one eventually, both because of the current annual discrepancy of
about 27 seconds between the Gregorian and tropical years, and because
of future changes in the length of the tropical year.

--
John Cowan  [EMAIL PROTECTED]  www.reutershealth.com  www.ccil.org/~cowan
If a traveler were informed that such a man [as Lord John Russell] was
leader of the House of Commons, he may well begin to comprehend how the
Egyptians worshiped an insect.  --Benjamin Disraeli

Re: Longer leap second notice

[John Cowan]

Clive D.W. Feather scripsit:
> John Cowan said:
> > Barry gules and argent of seven and six,    John Cowan
> > on a canton azure fifty molets of the second.   [EMAIL PROTECTED]
> > --blazoning the U.S. flag   http://www.ccil.org/~cowan
>
> You don't get odd numbers of barry. It's "Gules, six bars argent".

I have received comments to this effect, but also to the opposite effect.
In any case, the Great Seal of the United States is blazoned in the
enabling legislation "[p]aleways of thirteen pieces, argent and gules",
which is certainly relevant precedent, since the even-only theory of
"barry" is also usually applied to "paly".

Infinite are the arguments of mages.

--
One Word to write them all, John Cowan <[EMAIL PROTECTED]>
  One Access to find them,  http://www.reutershealth.com
One Excel to count them all,http://www.ccil.org/~cowan
  And thus to Windows bind them.--Mike Champion

Re: civil time = solar time

[John Cowan]

Rob Seaman scripsit:

> Rather, the often repeated canard that civilians don't give a fig for
> the actual position of the sun in the sky implies that it is
> precisely apparent solar time that only queer ducks like astronomers
> care about.  Mean solar time is what civilians DO care about.

Most civilians, with some exceptions like Orthodox Jews, Muslims, and
farmers, care about LCT, and LCT only has to meet PHK's criteria.

--
Do NOT stray from the path! John Cowan <[EMAIL PROTECTED]>
--Gandalf   http://www.ccil.org/~cowan

Re: Longer leap second notice

[John Cowan]

Ed Davies scripsit:

> The main requirements for local civil time for the bulk of its
> users are that:

Agreed.

>  1. local civil time matches apparent solar time roughly (e.g., the
> sun is pretty high in the sky at 12:00 and it's dark at 00:00).

I think the last is the important point, or more specifically that the
bulk of the population not begin work on one day and end on another
(astronomers excepted, of course).  This would be a bookkeeping nightmare.

--
Barry gules and argent of seven and six,    John Cowan
on a canton azure fifty molets of the second.   [EMAIL PROTECTED]
--blazoning the U.S. flag   http://www.ccil.org/~cowan

Re: GMT -> UTC in Australia

[John Cowan]

Tom Van Baak scripsit:

> Rob, this will always be true, won't it? Whether you
> have 100 ms time step adjustments, or 100 x e-10
> rate adjustments, leap seconds, or leap hours it
> seems to me there has been and will always be an
> honest attempt to "coordinate" the two scales.

No, no.  Leap hours are qualitatively different: they change the adjustment
between TAI and LCT, ignoring earth rotation altogether.

--
I marvel at the creature: so secret and John Cowan
so sly as he is, to come sporting in the pool   [EMAIL PROTECTED]
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Men sleep without watch all night?  --Faramir   http://www.ccil.org/~cowan

Re: GMT -> UTC in Australia

[John Cowan]

Rob Seaman scripsit:

> Not silly - and not secular.  Astronomers (at least) use the term
> "secular" to imply monotonic - and therefore cumulative - effects.

Ah, I didn't grasp that point, and was merely using it to mean "not
periodic".

> TZ changes mentioned are merely examples of single isolated events.

Indeed.

> Which is perhaps what Mr. Cowan means, and what the advocates of
> tolerance for bad temporal system design are certainly relying on.

No, that wasn't in my mind.  But it reminds me of the Secular Games in
ancient Rome, which were in fact periodic!

> UTC is a useful approximation to GMT.  Keep it that way and call
> any new system of civil time that might win the day something else.
> It is the height of intellectual dishonesty to do otherwise.

Fair enough.

--
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If your arguments lose the first round  http://www.reutershealth.com
Make it rhyme, make it scan http://www.ccil.org/~cowan
Then you generally can  [EMAIL PROTECTED]
Make the same stupid point seem profound!   --Jonathan Robie

Re: GMT -> UTC in Australia

[John Cowan]

Rob Seaman scripsit:

> "Ad hoc" is not a synonym for secular.  I'm pleased to see someone
> other than the astronomers in this conversation using the word secular,
> but there continues to be a fundamental confusion of Daylight Saving
> clock adjustments (periodic) with the silly notion of leap hours
> (fundamentally secular).

Not by me.  There have been genuinely secular changes in zone, call
them silly or not:  Pacific/Enderbury (Phoenix Islands Time) changed
its time zone from -11:00 to +13:00 in 1995, and Asia/Kashgar (extreme
western China) changed its time zone from -5:00 to -8:00 in 1980-05
(its LMT is 5:03:56).

> No reasonable standard can be based on constraining the behavior of our
> descendants 600 years hence.

They are only constrained in the sense that Pope Gregory was constrained
by the decisions of Julius Caesar.  By 2600 we may simply not care about
the apparent position of the sun (or anything else, perhaps).

--
John Cowan  [EMAIL PROTECTED]  www.reutershealth.com  www.ccil.org/~cowan
[R]eversing the apostolic precept to be all things to all men, I usually [before
Darwin] defended the tenability of the received doctrines, when I had to do
with the [evolution]ists; and stood up for the possibility of [evolution] among
the orthodox -- thereby, no doubt, increasing an already current, but quite
undeserved, reputation for needless combativeness.  --T. H. Huxley

Re: GMT -> UTC in Australia

[John Cowan]

Steve Allen scripsit:

> Yes.  But I can't say whether they value the immediate practicality of
> uniform time over the need to change all time zones by an hour 600
> years from now, and more and more often after that.

*sigh*

Secular changes in time zones (if by "time zone" you mean "LCT - UTC",
as I suppose) are something we already know how to handle, as they must be
taken into account when determining historical UTC/GMT to LCT conversion.
Indeed, some countries jigger the dates of their semiannual time changes
annually, which is also a secular change in a small way.

In addition, there is no reason why all the world's time zones must
change in a synchronized way; ad hoc changes, as and when the problems
become irritating, will be sufficient.  Some jurisdictions might choose
to change by half-hour offsets in only three centuries.

The legal documents I have inspected are quite careful about this: they
state things like lease expiration as "midnight, December 31, 2096, New
York time", abstaining from attempting to prescribe the definition of
"New York time" a century hence.

--
Only do what only you can do.   John Cowan <[EMAIL PROTECTED]>
  --Edsger W. Dijkstra's advice http://www.reutershealth.com
to a student in search of a thesis  http://www.ccil.org/~cowan

Re: The Eleven Days

[John Cowan]

Clive D.W. Feather scripsit:

> See also <http://www.davros.org/misc/easter.html> and the Easter Act 1928.

Most interesting, and an excellent Web site.

--
"[T]he Unicode Standard does not encode John Cowan
idiosyncratic, personal, novel, or private  http://www.ccil.org/~cowan
use characters, nor does it encode logoshttp://www.reutershealth.com
or graphics."   [EMAIL PROTECTED]

The Eleven Days

[John Cowan]

Clive D.W. Feather scripsit:

> What, I wonder, did the various churches do about the Eleven Days?

Why, nothing.

> They can hardly have been taken down and rebuilt at a slight angle,
> after all.

Orienting to saints' days was an architectural nicety, not a dogmatic
requirement.  Even the general principle of aligning the church to the
East is frequently violated in modern times, where churches have to fit
into city grids like Manhattan's (which is aligned to the long axis of
the island, so that "north" (or "uptown") is about 30 degrees, not 0).

The 1751 Act of Parliament that changed "the legal Supputation of the
Year" explicitly excepted certain recurring dates from the change, so that
they would occur on the same "natural Days" as before, and consequently on
different "nominal Days": terms of courts and the dates of markets, fairs,
opening and enclosing of commons, and payments of rents and annuities.
(The dates specified in contracts for the delivery of goods, for the
commencement and expiration of leases, and the legal majority age of
individuals born before 1752-09-14 Gregorian, were similarly adjusted.)
Consequently, the beginning of the tax year in England remained on Old
New Year's Day, 25 March Julian, until 1900, when it should have been
updated to April 7 Gregorian but wasn't.  Oh well.

(Full text: http://webexhibits.org/calendars/year-text-British.html)

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Re: two world clocks AND Time after Time

[John Cowan]

Tom Van Baak scripsit:

> Another observation is that our local newspaper always
> prints Sun and Moon rise and set times. But not time
> of noon. Why is this? Maybe it's just our paper (noon
> implies sun and we don't see much of it here in Seattle).

Some people need to know sunset for religious reasons, and perhaps
sunrise is occasionally useful too; I have been checking sunset times
lately to figure out when to tell my daughter to be at home by.
Solar noon just doesn't have the same importance.

> Sure, but it seems to me - regardless of the timezone,
> regardless of daylight saving time, regardless of the
> season, regardless of latitude, to the general public
> 12:00 means lunchtime (or their VCR got unplugged).
> The sun doesn't have much say about it.

Amen.

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Re: two world clocks AND Time after Time

[John Cowan]

Steve Allen scripsit:

> What we are being told by the Time Lords is that, starting from a date
> in the near future, knowing when noon is will also be a specialist
> operation.

Already true.

For many months of the year, solar noon is closer to 1 PM, or even 1:30
PM, in a great many countries, and how many people actually realize
*that*?

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Re: Time after Time

[John Cowan]

Markus Kuhn scripsit:

> UTC currently certainly has *no* two 1-h leaps every year.

There seems to be persistent confusion on what is meant by the term
"leap hour".  I understand it as a secular change to the various LCT offsets,
made either all at once (on 1 Jan 2600, say) or on an ad-lib basis.
You seem to be using it in the sense of a 1h secular change to universal
time (lower-case generic reference is intentional).

Can anyone quote chapter and verse from Torino to show exactly what was
meant?  Or is the text in fact ambiguous?

> If you read, just one example, to deviate a bit from the overwhelmingly
> US/UK-centricism of this legal argument,

I keep talking about the Chinese example.  Consider the city of Kashi,
population about 175,000.  Its longitude is about 76 E, which means
that its LMT is about GMT+5.  Its LCT, however, is Asia/Shanghai, or
UTC+8.  If all those people can live with an LCT that is three hours
away from the sun, we can stand rather lower discrepancies just fine.

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Re: two world clocks

[John Cowan]

Joseph S. Myers scripsit:

> Which just makes it the more curious that the Danish language version of
> the last Summer Time Directive
> 
> specifies the start and end times of summer time in UTC, whereas the
> English language version
> 
> says Greenwich Mean Time.

Chauvinism and nothing but.  The English remain suspicious of any locution where
an adjective appears after its noun (unless indeed it is hallowed by centuries
of tradition, as in the case of "attorney-general").

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Re: two world clocks

[John Cowan]

Rob Seaman scripsit:

> b) Currently the tables are maintained and updated by members of the
> precision timing community who should indeed be commended for their
> excellent work over the last quarter century and more.  The proposal on
> the table would require all 6+ billion of us to keep his or her own
> tables up-to-date.  The current situation is better.

I don't understand that at all.  People who need Earth angle (and I am
*not* opposed to making that widely available) will need to pick up
a correction table from IERS, there's no doubt about that.  IERS will
continue in exactly its current mission, it's just that its output
will no longer affect the value of LCT.

And as for keeping tables up to date, that's exactly what programmers
(especially programmers of embedded systems) are complaining about having
to do now, just to track UTC and LCT.

> People need good sources of time for a
> variety of reasons.  We are discussing a complete abandonment of the
> provision of Earth "rotation information" to the civilian public
> worldwide.

Not at all.  We are simply abandoning the notion that LCT is the right
way to provide that information.

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Re: two world clocks

[John Cowan]

Rob Seaman scripsit:

> What exact future systems are we discussing that will both 1) require
> the use of Universal Time and 2) not require a definition of Universal
> Time that is tied to the rotating Earth?

*sigh*

LCT is currently tied to UTC, and converting a count of SI seconds to
a UTC time is currently (a) annoying and (b) depends on updating tables.

> Attempting to move the entire worldwide civil time system to a
> non-Earth based clock is equivalent to attempting to build a clock
> designed to run untended for 600 years - in effect, to attempting to
> build a millennium clock.  The alarm must be designed to ring in 599
> years time.

This is simply not true.  The LCT-TI offsets can be adjusted locally as and
when they individually start to be a problem.  No global changeover is required.

> Systems that don't need time-of-day should use TAI.

Wall clocks need to run in LCT, which is currently founded on UTC.  Most people
don't need precision time-of-day (which should be rightly called "Earth angle"
and measured in SI radians).  They just need there to be a rough correlation
between LCT and the sun, and several hours' discrepancy can be tolerated.
Just go to Urumqi, or Detroit if Urumqi is too remote.

> And most definitely, let's stop these inane and embarrassing closed
> door discussions among biased insiders.

Personally, I am a biased outsider.

> It ain't your clock - it's *our* clock.

Eh?  Who are "you" and who are "we"?

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