Re: building consensus
On Mon 2006/06/05 22:04:40 -0400, John Cowan wrote in a message to: LEAPSECS@ROM.USNO.NAVY.MIL 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. There were two such, one labelled EST and the other EDT, neither were official but either could still be used without ambiguity. At the other end of the season there will be two and both will be official. C.f. email from me dated 2006/01/13 on this subject. Mark Calabretta
Re: building consensus
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). Unsurprisingly, Ireland originally followed the UK tax year. However, in 2000 the tax year ran from April 6 until December 31. Since then our tax year is in sync with the calendar year. (I guess this is a recent example of calendar reform that went relatively smoothly.) David.
Re: building consensus
Rob Seaman said: In the UK in 1750, there were two different Julian calendars in use: the day and month enumeration matched, but year numbers changed at different dates (1st January in Scotland, 25th March in England and Wales). I've heard this said, but what exactly does this mean from the point of view of the people of the time? Could see how the 1st of any month would be as good as any other for marking the count of years. But presumably you are saying something like that the sequence of dates was: 22 March 1750 23 March 1750 24 March 1750 25 March 1751 26 March 1751 27 March 1751 Right? Correct. To quote *current* UK law: That in and throughout all his Majesty's Dominions and Countries in Europe, Asia, Africa, and America, belonging or subject to the Crown of Great Britain, the said Supputation, according to which the Year of our Lord beginneth on the 25th Day of March, shall not be made use of from and after the last Day of December 1751; and that the first Day of January next following the said last Day of December shall be reckoned, taken, deemed and accounted to be the first Day of the Year of our Lord 1752; and the first Day of January, which shall happen next after the said first Day of January 1752, shall be reckoned, taken, deemed and accounted to be the first Day of the Year of our Lord 1753; and so on, from Time to Time, the first Day of January in every Year, which shall happen in Time to come, shall be reckoned, taken, deemed and accounted to be the first Day of the Year; and that each new Year shall accordingly commence, and begin to be reckoned, from the first Day of every such Month of January next preceding the 25th Day of March, on which such Year would, according to the present Supputation, have begun or commenced: What this suggests to me is that the day-of-the-month and year-of-our- Lord counts were considered to be separate entities by folks of that time. Right. Was also thinking to comment that day-of-the-week seems to have been considered quite distinct from day-of-the-month. Our current usage is to tie all three together into a single unitary calendar. Presumably this dates from Gregory, too, along with all the other cycles his priests were seeking to synchronize. No, this seems to be *much* older, coming from Jewish practice. Gregory didn't touch the sequence of days of the week. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
Zefram said: Looks a lot like that. They used not to be, though: it seems that the oldest convention was to start the counted year on January 1, where Julius had put (well, left) the start of the calendar year. Um, March was the first month of the year; look at the derivation of September, for example. It seems that it moved to January in 153 B.C. Wikipedia suggests it was 15th March before that (because the consuls took office on the Ides of March). Counting the year from a different point is a distinctly mediaeval practice. See above. Yes. The seven day week is effectively a small calendar unto itself, and one much older than any of the year-based calendars we've been discussing. The Julian calendar was developed for a society that didn't use the week at all. The week was adopted by the Roman Empire centuries later, as part of its Christianisation. The *seven* day week was, but before then the Romans had a rigid *eight* day week. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
Poul-Henning Kamp said: 22 March 1750 23 March 1750 24 March 1750 25 March 1751 26 March 1751 27 March 1751 I belive this was because the year followed the taxation cycle of the government whereas the day+month followed the religiously inherited tradtion. The 25th March is one of the four Quarter Days in England, when traditionally quarterly rents were paid. In Scotland 1st January is a Quarter Day. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
Ed Davies said: Yes, I think that's right. And, as I understand it, we still keep that change of year in mid-month but now it's on April 5th for the change of tax year. When we switched from the Julian to the Gregorian calendar the tax year was kept the same length so its date changed. That was another requirement of the legislation: Provided also, and it is hereby further declared and enacted, That nothing in this present Act contained shall extend, or be construed to extend, to accelerate or anticipate the Time of Payment of any Rent or Rents, Annuity or Annuities, or Sum or Sums of Money whatsoever, which shall become payable by Virtue or in Consequence of any Custom, Usage, Lease, Deed, Writing, Bond, Note, Contract or other Agreement whatsoever, now subsisting, or which shall be made, signed, sealed or entred into, at any Time before the said 14th Day of September, or which shall become payable by virtue of any Act or Acts of Parliament now in Force, or which shall be made before the Said 14th Day of September, or the Time of doing any Matter or Thing directed or required by any such Act or Acts of Parliament to be done in relation thereto; or to accelerate the Payment of, or increase the Interest of, any such Sum of Money which shall become payable as aforesaid; or to accelerate the Time of the Delivery of any Goods, Chattles, Wares, Merchandize or other Things whatsoever; or the Time of the Commencement, Expiration or Determination of any Lease or Demise of any Lands, Tenements or Hereditaments, or of any other Contract or Agreement whatsoever; or of the accepting, surrendering or delivering up the Possession of any such Lands, Tenements or Hereditaments; or the Commencement, Expiration or Determination of any Annuity or Rent; or of any Grant for any Term of Years, of what Nature or Kind soever, by Virtue or in Consequence of any such Deed, Writing, Contract or Agreement; [...] but that all and every such Rent and Rents, Annuity and Annuities, Sum and Sums of Money, and the Interest thereof, shall remain and continue to be due and payable; and the Delivery of such Goods and Chattles, Wares and Merchandize, shall be made; and the said Leases and Demises of all such Lands, Tenements and Hereditaments, and the said Contracts and Agreements, shall be deemed to commence, expire and determine; and the said Lands, Tenements and Hereditaments shall be accepted, surrendered and delivered up; and the said Rents and Annuities, and Grants for any Term of Years, shall commence, cease and determine, at and upon the same respective natural Days and Times, as the same should and ought to have been payable or made, or would have happened, in case this Act had not been made; and that no further or other Sum shall be paid or payable for the Interest of any Sum of Money whatsoever, than such Interest shall amount unto, for the true Number of natural Days for which the principal Sum bearing such Interest shall continue due and unpaid; In other words, all financial matters are to be done by day count and not by calendar date. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
John Cowan said: 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. No, I think it's just that my memory has converted 24.7 into 27. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
Clive D.W. Feather wrote: So humans will cope until the solar day is about 27 (present) hours long, after which we'll probably start to move to a system of two sleep-wake cycles per day. I doubt our ability to handle a 14-hour sleep-wake cycle. I suspect that (if we're still exposed to the natural diurnal cycle at that time) as we gradually lost the ability to handle the length of the diurnal cycle we'd lose synchronisation fully, or switch to a fractional multiple of the cycle. A 24-hour sleep-wake cycle against a 28-hour diurnal cycle repeats phase correlation every seven sleep-wake cycles (six days), so we might lock to that. Hey, it's a natural justification for the week! Perhaps it would be similar in effect to the present desynchronisation of the Islamic calendar's `year' with respect to the tropical year. When I was an undergraduate I found that my free-running sleep-wake cycle was 40 hours long (24 hours awake and then 16 asleep, to within half an hour). I don't think I phase-locked to the diurnal cycle in the 3:5 ratio that implies, but the whole reason why I got into that cycle was that I wasn't paying attention to the planet's rotation. -zefram
Re: building consensus
Clive D.W. Feather wrote: March was the first month of the year; look at the derivation of September, for example. 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 *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. Rob NOAO
Re: building consensus
On Thu, 8 Jun 2006, Rob Seaman wrote: Clive D.W. Feather wrote: March was the first month of the year; look at the derivation of September, for example. 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. hang on I thought the numbering start Jan=1 ... Dec=10 and got interrupted when Julius Caesar put an extra month in and so did Augustus... Hands up if you wish you had the authority to swing that kind of timekeeping standardization adjustment. Pete.
Re: building consensus
John Cowan wrote: 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. Thanks! But not sure true story is the opposite of cover story, here :-) Both versions of the book are sitting in a box somewhere in the garage. It must be twenty or thirty years since I read whichever. Few writers other than Clarke had the chutzpah or cleverness to write a viable story placed billions of years in the future. Now that you mention the lunar plot twist, I do remember something about it - strange that other aspects of the story remain much more vivid. Of course, the other civilizations were tossing stars around, not just moons, so it may have seemed pedestrian. Rob NOAO
Re: building consensus
On Thu, 8 Jun 2006, Rob Seaman wrote: I thought Julius renamed some high value summer month and wanna-be Augustus did likewise, stealing a day from February to make August the same length. If they put two extra months in, where were those 62 days originally? Yes of course, and a quick google as usual turns up a well-written account: http://www.infoplease.com/spot/99aughistory1.html
Re: building consensus
Hands up if you wish you had the authority to swing that kind of timekeeping standardization adjustment. It's a lot easier to get consensus if you are willing and able to kill those with opposing viewpoints. :)
Re: building consensus
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
Rob Seaman said: I thought Julius renamed some high value summer month and wanna-be Augustus did likewise, stealing a day from February to make August the same length. If they put two extra months in, where were those 62 days originally? Very briefly: - Julius and Augustus renamed months 5 and 6 respectively; - Augustus moved one day from February to August as you say; - the extra months (January and February) were inserted by Numa in the 8th century BCE; until then there were no names for winter dates; - until Julius's reforms, there was an intercalary *month* rather than day, inserted (I think) after February; - Julius created a single 15 month year as a one-off adjustment to bring calendar back in line with the sun. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
Rob Seaman said: John Cowan wrote: 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. Thanks! But not sure true story is the opposite of cover story, here :-) Both versions of the book are sitting in a box somewhere in the garage. 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?). For example, the official story is that Diaspar was the centre of a human interstellar empire, while the true story is that man was part of a multi-species federation. It's these two stories that differ in what happened to the moon. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
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
In message [EMAIL PROTECTED], John Cowan writes: Rob Seaman 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. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
Re: building consensus
Quintilis was renamed after Julius Caesar. Later Sextilis was renamed after Augustus Caesar. It is often said that the month lengths were changed at the same time, but at least one version of that story is fabricated and there's a distinct lack of evidence for it. Other emperors had months renamed after themselves too, but those names didn't stick. There's no evidence that any of them was accompanied by changes in the lengths of months either. The Oxford Companion to the Year is pretty explicit about this in its chapter on the Roman Calendar. It says that before Julius Caesar: Ianuarius29 Quinctilis 31 Februarius 28 Sextis 29 Martius 31 September29 Aprilis 29 October 31 Maius31 November 29 Iunius 29 December 29 The reason was most of the months had odd lengths because odd numbers were lucky, but to get the year to have an odd number of days you need one month to have an even number of days. There was a leap month system where Februarius was cut short and an extra month was inserted. After the reform: Ianuarius31 Quinctilis 31 Februarius 28 Sextis 31 Martius 31 September30 Aprilis 30 October 31 Maius31 November 30 Iunius 30 December 31 They also explain where the extra days were inserted. They say Quinctilis was renamed Julius after he'd been murdered. Their entry for 30 February notes: There is no truth in the assertion by some modern (but no ancient) writers that Julius Caesar gave all the odd months 31 days, February 29 days and 30 in a leap year, and all the even months (including Oct) 30, but that Augustus upsets the logical arangement in order to make his month of August as long as Caesar's July. Nevertheless, 30 February has existed three times in the calendars of particular countries: once in Sweden, twice in the Soviet Union. David.
Re: building consensus
On Jun 8, 2006, at 8:08 AM, Clive D.W. Feather wrote: Rob Seaman said: Thanks! But not sure true story is the opposite of cover story, here :-) 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 Right. Was merely questioning whether a story within a story within a work of fiction could be regarded as true :-)
Re: building consensus
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
Rob Seaman said: 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. Just returned from a conference three hours to the east. The existence of jet lag suggests significant evolutionary pressure locking human sleep cycles to the length of the day. Actually, the evidence from experiments is that the natural sleep-wake cycle is about 27 hours long, but force-locked to the day-night cycle (it's easier to synchronise a longer free-running timer to a shorter external signal than vice-versa). So humans will cope until the solar day is about 27 (present) hours long, after which we'll probably start to move to a system of two sleep-wake cycles per day. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
John Cowan said: 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. Even worse, Julian can have more than one meaning. In the UK in 1750, there were two different Julian calendars in use: the day and month enumeration matched, but year numbers changed at different dates (1st January in Scotland, 25th March in England and Wales). -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | Fax:+44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 THUS plc||
Re: building consensus
On Jun 7, 2006, at 2:01 AM, Clive D.W. Feather wrote: Actually, the evidence from experiments is that the natural sleep- wake cycle is about 27 hours long, but force-locked to the day-night cycle (it's easier to synchronise a longer free-running timer to a shorter external signal than vice-versa). 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 :-) So humans will cope until the solar day is about 27 (present) hours long, after which we'll probably start to move to a system of two sleep-wake cycles per day. Well, cope isn't the right word if this cycle is as you describe. Also hard to imagine how one gracefully transitions from one to two sleep cycles a day. It would simply appear that the underlying mechanism evolved to rely on a slightly longer free-running timer synchronized to length-of-day. As the day lengthens, Darwin would predict that our intrinsic cycle would also lengthen. This is similar to arms races leading to other periodic natural behavior such as prime number 13 and 17 year locusts. (Non-primes would allow locust predators to emerge more frequently while locking into the phase, thus gaining an advantage.) Also, whether or not one believes that humans have somehow escaped the grip of evolution, it is hard to imagine our continued sojourn on Mother Earth half a billion years hence :-) Obvious lines of research for further sleep period investigations would be to examine similar cycles in other animals. One imagines this is some function of the nervous system, so one might also contrast strategies pursued by plants and animals without. Also - how is this intrinsic cycle inferred? Could signatures of this intrinsic cycle be preserved in the fossil or DNA record? All sorts of other cycles are. Could such signatures be correlated with length- of-day at various epochs? Just another mechanism tying our species to time-of-day. Rob NOAO
Re: building consensus
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
Tim Shepard replies: Also hard to imagine how one gracefully transitions from one to two sleep cycles a day. It is already the norm in some places: http://en.wikipedia.org/wiki/Siesta Thanks for the chuckle. One is then left wondering whether our far future, Clarkeian Against the Fall of Night/City and the Stars, descendants will enjoy *two* siestas per day. With inhabitants being reconstituted every few millennia from a computer database, one might argue that evolution will have indeed ceased - so they won't be adapting to the lengthening day by natural selection. Of course, they may have artificially stabilized the Earth's rotation by that point, too :-) Does anyone remember if Earth-Moon dynamics plays a role in the story? Rob
Re: building consensus
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
Rob Seaman wrote: Doubt I can lay my hands on the copy of ISO 8601 from my Y2K remediation days. Anybody want to comment on whether it actually attempts to convey the Gregorian algorithm within its pages? Yes, it does. This International Standard uses the Gregorian calendar for the identification of calendar days. The Gregorian calendar provides a reference system consisting of a, potentially infinite, series of contiguous calendar years. Consecutive calendar years are identified by sequentially assigned year numbers. A reference point is used which assigns the year number 1875 to the calendar year in which the “Convention du mètre” was signed at Paris. The Gregorian calendar distinguishes common years with a duration of 365 calendar days and leap years with a duration of 366 calendar days. A leap year is a year whose year number is divisible by four an integral number of times. However, centennial years are not leap years unless they are divisible by four hundred an integral number of times. This is from section 4.3.2.1 of the final draft of ISO8601:2000. It's also an interesting quote in that it suggests that the 1875 Convention du mètre is important in the international definition of the Gregorian calendar. Anybody know more on that? Ed.
Re: building consensus
Ed Davies quoted:The Gregorian calendar provides a reference system consisting of a,potentially infinite, series of contiguous calendar years. Consecutivecalendar years are identified by sequentially assigned year numbers.A reference point is used which assigns the year number 1875 to thecalendar year in which the “Convention du mètre” was signed at Paris.The Gregorian calendar distinguishes common years with a durationof 365 calendar days and leap years with a duration of 366 calendardays. A leap year is a year whose year number is divisible by fouran integral number of times. However, centennial years are not leapyears unless they are divisible by four hundred an integral numberof times. This is from section 4.3.2.1 of the final draft of ISO8601:2000.This does not express a complete algorithm, of course, since it is not tied to the days of the week. One presume the zero point of 1875 was selected as a practical compromise with historical realities. One questions whether the Gregorian calendar can be used to express dates before 1582-10-15, and it is ambiguous for large parts of the world until the mid-eighteenth century. Still in 1875, it had not reached all locales. Etc.Zefram wrote:Pope Gregory, of course, used a different epoch. The original Papal Bulldidn't use a well-known event such as this, but instead effectively said1582 October 5 Julian = 1582 October 15 Gregorian.This is very familiar territory since I had two semesters of the History of Astronomy from an Augustinian priest. I had not previously read through the Papal Bull in question, however. I wouldn't rely on this as a fundamental reference, but see the translation at: http://personal.ecu.edu/mccartyr/intGrvEng.htmlA few comments. First, the name of the Bull is "Inter Gravissimas" or roughly "Among the most serious". These are not issues to be trifled with. Second, from paragraph 5: "Our dear son Antonio Lilio, professor of science and medicine, brought to us a book, written at one time by his brother Aloysius [Luigi], in which this one showed that, by means of a new cycle of epacts which he had devised, and who directed his own particular Golden Number pattern and accomodated the entirety of any solar year, every [defect of] the calendar collapsed, and the constant calculations would endure for every generation. He was, thus, able to restore and explain how the calendar itself will never need published any further change."A worthy goal. That residual discrepancies (that were presumably within the measurement error in the sixteenth century) will ultimately require currently unscheduled modifications to the Gregorian calendar, does not diminish the achievement of Aloysius/Luigi.A successful proposal to reform civil time (as with the civil calendar) should exhibit this same worthy goal of actually improving the status quo, rather than simply arranging to ignore a reality that will return with a vengeance after 600 years.Gregory also had a refreshing attitude toward the standards process: 1) "This new project of the restoration of the calendar, summarized in a small book, we forwarded a few years ago to the Christian princes and to the large universities so that this work, which is the business of all, is carried out with the consultation of all." 2) "Those having expressed their agreement to us, as we had sincerely hoped, we have, with this consensus, arranged a gathering in the Holy City, to reform the calendar, of the very qualified men on the matter whom we had chosen from the principal countries of the Christian world a long time before." 3) "Those, after having devoted much time and attention to this night work and having discussed between them cycles which they had collected from everywhere, old ones as well as modern ones, and as they had carefully studied the reflections and the opinions of erudite men who wrote on this subject, chose and prefered this cycle of epacts," 4) "adding to it elements which, after thorough examination, appeared essential to the realization of a perfect calendar."So, they: invested sufficient time to understand the issues - recognized the extremely broad range of stake holders - sought their advice and consent in characterizing the problem - invited representatives to help craft the solution - and more to the point, were looking for an actual solution, not some imaginary bandaid.Rob SeamanNOAO
Re: building consensus
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
In message: [EMAIL PROTECTED] John Cowan [EMAIL PROTECTED] writes: : 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. Yes. To find a second absolute time that represents the same wall time a minute/hour/day later is why posix time_t has this property. This is abstime + delta, which is a little different than the difference between two time_t. : You may call this position wrong (and I have done so), but it is : unquestionably defensible. Differences in time_t are adjusted by leapseconds. This makes naive math work for the ABSTIME+delta case, but breaks the difference case when you want an actual elapased time. It is an engineering tradeoff, but an inconvenient one for the problem domains that I tend to have to solve. Warner
Re: building consensus
On Jun 4, 2006, at 9:57 PM, M. Warner Losh wrote: leap days have a rule, while leap seconds are scheduled. 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. 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?) If we have to spend all our time fending off this silly leap hour proposal, we'll never have the opportunity to focus on rules and algorithms (not to mention technology and infrastructure). Just don't do it is not a rule. The biggest difference between leap days and leap seconds is that days are quantized. Rob NOAO
Re: building consensus
From: Rob Seaman [EMAIL PROTECTED] Subject: Re: [LEAPSECS] building consensus Date: Mon, 5 Jun 2006 08:35:39 -0700 On Jun 4, 2006, at 9:57 PM, M. Warner Losh wrote: leap days have a rule, while leap seconds are scheduled. A schedule and a rule are the same thing, just regarded from different historical perspectives. Leap days have an iron-clad rule that generates the schedule on which they happen. Leap seconds have a committee that generates the schedule on which they happen. A rule implies that it is long term, I guess. Maybe there's a better word for that implication. The leap day rule will most certainly have to accommodate scheduling changes over the millennia. True. 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?) If we have to spend all our time fending off this silly leap hour proposal, we'll never have the opportunity to focus on rules and algorithms (not to mention technology and infrastructure). We have discussed having some kind of rule for when leap seconds are inserted. So far, none of these 'rules' are that long term. follow this table for the next 10 years or for the next 10 years, we'll have one every 18 months are simplified versions of the proposals I've seen. These have a very limited time horizon. The biggest difference between leap days and leap seconds is that days are quantized. I'm afraid I don't understand this statement. Care to explain? Warner
Re: building consensus
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
Warner Losh wrote: A rule implies that it is long term, I guess. Maybe there's a better word for that implication. In the realm of calendars the terminology is arithmetic versus observational. That's one of the things I included at the start of this thread. I'd also like to throw in the word deterministic. The leap day rule will most certainly have to accommodate scheduling changes over the millennia. True. But any such change would constitute the adoption of a new calendar, not an observational aspect of the present one. The Gregorian calendar itself is strictly arithmetic and thus immutable. 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. -zefram
Re: building consensus
Warner Losh wrote: A rule implies that it is long term, I guess. Maybe there's a better word for that implication. In the realm of calendars the terminology is arithmetic versus observational. That's one of the things I included at the start of this thread. I'd also like to throw in the word deterministic. I missed that terminology, and I like it a lot better than the terminology I've been using. Thank you! UTC is an observationally based time scale... I like how that sounds... 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. The Theory file in the current time zone files has some very interesting information about this. There's a 'Calendrical Issues' section that talks about these issues. There's a reference to a book http://emr.cs.uiuc.edu/home/reingold/calendar-book/index.shtml which is good. The problem is that many authoritative sources on these matters often disagree what happened. I'm sure that someone has taken this as the basis for starting a more comprehensive database. Here's a few of my favorite entries: In 1700, Denmark made the transition from Julian to Gregorian. Sweden decided to *start* a transition in 1700 as well, but rather than have one of those unsightly calendar gaps :-), they simply decreed that the next leap year after 1696 would be in 1744 -- putting the whole country on a calendar different from both Julian and Gregorian for a period of 40 years. However, in 1704 something went wrong and the plan was not carried through; they did, after all, have a leap year that year. And one in 1708. In 1712 they gave it up and went back to Julian, putting 30 days in February that year!... Russia From Chris Carrier [EMAIL PROTECTED] (1996-12-02): On 1929-10-01 the Soviet Union instituted an ``Eternal Calendar'' with 30-day months plus 5 holidays, with a 5-day week. On 1931-12-01 it changed to a 6-day week; in 1934 it reverted to the Gregorian calendar while retaining the 6-day week; on 1940-06-27 it reverted to the 7-day week. With the 6-day week the usual days off were the 6th, 12th, 18th, 24th and 30th of the month. If your source is correct, how come documents between 1929 -- 1940 were still dated using the conventional, Gregorian calendar? I can post a scan of a document dated December 1, 1934, signed by Yenukidze, the secretary, on behalf of Kalinin, the President of the Executive Committee of the Supreme Soviet, if you like.
Re: building consensus
On Jun 5, 2006, at 8:45 AM, Warner Losh wrote:Leap days have an iron-clad rule that generates the schedule on whichthey happen. Leap seconds have a committee that generates theschedule on which they happen.Further discussion in this thread calls into question the characterization of "iron-clad rule" :-)One might ponder what standards body is responsible for the international calendar specification. Is it the Roman Catholic church? Or has the specification passed into the public domain? Are individual nations each responsible for their own calendars? If so, mustn't they then be responsible for trade and scientific purposes for providing tables of conversions between their national calendar and the international standard? Which then returns us to the question of who is responsible for that international standard...We have discussed having some kind of rule for when leap seconds are inserted.Yes, but note that the IERS could institute a wide variety of scheduling algorithms *on top of* the current monthly (or twice yearly) leap second constraint. If the state of the art allowed predicting UT1 for a decade in advance, a table of leap seconds could be provided a decade in advance. This option requires even less of a change than the Absurd Leap Hour Proposal (ALHP).On Jun 5, 2006, at 8:57 AM, John Cowan wrote:On the other hand, I am sure we haven't exhaustively discussedpossible refinements to the leap second "scheduling algorithm". (Andain't that a rule?)I thought the whole point was that while we had a rather good predictionof changes in the tropical year (viz. none), and therefore only have todink with the calendar when the current error of about 8.46 seconds/yearaccumulates to an uncomfortably large value, there is simply no knowing,in the current state of our geophysical knowledge, how the wobbly oldboulder in the sky is going to wobble next.The biggest difference between leap days and leap seconds is thatdays are quantized.Can you expound on this remark?A calendar counts days. A day - whether from noon to noon, midnight to midnight, sunrise to sunrise, or sunset to sunset - is an atomic "quanta" of time on earth. It also happens to be growing relative to the year. Ultimately calendrical and clock issues are the same. (The historical time horizons over which various effects matter for various purposes may be very different, of course.)The ALHP is an attempt to redefine the day.On Jun 5, 2006, at 9:27 AM, Zefram wrote:In the realm of calendars the terminology is "arithmetic" versus"observational". That's one of the things I included at the start ofthis thread. I'd also like to throw in the word "deterministic".The Gregorian calendar itself is strictly arithmetic and thus immutable.There is the alternate point of view that the calendar in actual civil usein a particular locality, changing between different arithmetic calendarsat 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.So the calendar is either immutable - or it isn't :-)I have a hard time reconciling the notion of a "calendar zone" with the definition of "deterministic" as: "an inevitable consequence of antecedent sufficient causes"For the sake of argument, however, assume that the Gregorian calendar is immutable - leap day every four years, except for even centuries not divisible by 400. What will then happen when the Gregorian calendar is inevitably deemed to fail to serve? Well, we already have historical precedent. The Gregorian calendar succeeded the Julian, just as the Julian succeeded what came before. That Caesar was more successful than Pope Gregory at convincing the world to rapidly adopt the new standard is a result of some pretty interesting historical differences between the two eras. The fundamental fact, however, is that a new calendar was completely substituted for the old. One might also note that the staged and delayed politically sensitive adoption of the Gregorian calendar was possible precisely because the Julian calendar continued in force. In fact, it continues as a standard to the present day. The Julian calendar was deprecated, but not redefined.Compare this with the ALHP. I might disagree quite strongly with the idea of a leap hour - but I wouldn't have quite the visceral hate and utter contempt for the idea if the proposal were to also substitute a new name. Instead of eviscerating UTC (a coherently defined entity that the ITU simply inherited), call it "McCarthy Time", for instance. One would think that just as the Julian and Gregorian calendars pay homage to Julius Caesar and Pope Gregory, that the eponymous "MT" would be taken as homage to its creator..and if not, ask yourself, why not?In what ways is the ALHP unworthy of its authors?RobNOAO
Re: building consensus
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 censored [EMAIL PROTECTED] DATE: MONDAK, JANUARK 1, 1900 http://www.ccil.org/~cowan
Re: building consensus
On Jun 5, 2006, at 1:05 PM, John Cowan wrote: (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.) 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. Rob NOAO
Re: building consensus
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
On Jun 5, 2006, at 1:38 PM, John Cowan wrote: 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. One might suggest that the accommodation between civil time and legal time is of more interest. What does it mean to say that some nation or locality uses the Gregorian - or any other - calendar, if some date legally does not exist as you suggest? The sun certainly came up on that day and rose the following day about 24 hours later. A variety of activities occurred on that day that fell into bins like weekday, weekend or holiday - or if this was some red letter day different from all others, then the authorities must have tacked up fliers or alerted town criers or otherwise informed the populace of the special nature of the day in question. When they did that, what did they call it? The day after December 30, 1844? Next Tuesday? (Which begs the question, of course.) Suspect rather that legal time only applied to certain specific interactions with colonial authorities. Would love more details. An observing session with a ground-based nighttime astronomical telescope typically begins on one calendar date and ends on the next. For some observatories in the western hemisphere, the session starts after 0h UT such that the entire session can be trivially labeled with a single date. The problem with this is that the UT date is one day after the date on the observing calendar. For observatories elsewhere, the data from a single coherent session are split between two dates whether local or UT time is used. The solution I have adopted for the dozen telescopes in my bailiwick is to establish a local noon pivot. All data are assigned to the calendar date at the start of the night. This 12h difference is, in effect, the maximum possible discrepancy between a legal date and a solar date. As always, the question is: what is your timekeeping application? 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. Rob NOAO
Re: building consensus
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
Rob Seaman wrote: One might ponder what standards body is responsible for the international calendar specification. Is it the Roman Catholic church? The RCC is authoritative for no calendar other than the RCC calendar. Originally this amounted to an endorsement of the Roman empire's then-current civil calendar, namely the Julian calendar, plus a formula for the date of Easter. The RCC then commissioned, and eventually endorsed, the replacement Gregorian calendar, along with a new Easter formula. Any future changes to the RCC calendar make no difference whatsoever to the use of the Gregorian calendar by any other administration. Or has the specification passed into the public domain? The algorithm is well-known and immutable. It is independent of any authority. One might equally refer to it as the ISO 8601 calendar rather than the Gregorian calendar. Are individual nations each responsible for their own calendars? Trivially yes, as a matter of law. It is precisely the same issue as time zones. mustn't they then be responsible for trade and scientific purposes for providing tables of conversions between their national calendar and the international standard? Which then returns us to the question of who is responsible for that international standard... Anyone promulgating a calendar is de facto responsible for providing the mapping between day labels and actual days. There's no de jure compulsion, but if they don't do this then it's no use as a calendar. Converting to other calendars is (conceptually) the composition of more than one of these mappings. The international standard, in this sense, is actual planetary rotations. Or you could view some form of Julian Date as the international standard. The Chronological Julian Day Number has some currency as a calendar intermediate format. This too doesn't need any responsible authority: the definition is well known. A calendar counts days. A day - whether from noon to noon, midnight to midnight, sunrise to sunrise, or sunset to sunset - is an atomic quanta of time on earth. I think this is no different from the situation with leap seconds. The precision time services, in TAI and UTC, provide a standardised 1 Hz cycle, dividing up proper time on the geoid into quanta of (as close as can be realised) 1 s. A leap second encompasses exactly one of these quanta. The difference between days of the Gregorian calendar and seconds of UTC is merely that the seconds are an artificial phenomenon. -zefram
Re: building consensus
On Jun 5, 2006, at 2:47 PM, John Cowan wrote: I'm not sure what you mean by civil time in this context. I meant whatever we've meant in this forum for the past five years. For some people, civil time is synonymous with standard time; for others, it means the time shown by accurate clocks in the locality. 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? 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. 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. 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. 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. Rob NOAO
Re: building consensus
On Jun 5, 2006, at 4:05 PM, Rob Seaman wrote: 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. I should clarify this to mean the underlying internationalized standard delta'ed to local time. Time zones are a trivial refinement of a unifying theme. Rob NOAO
Re: building consensus
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
On Mon 2006/06/05 11:07:00 MST, Rob Seaman wrote in a message to: LEAPSECS@ROM.USNO.NAVY.MIL Julian, just as the Julian succeeded what came before. That Caesar was more successful than Pope Gregory at convincing the world to rapidly adopt the new standard is a result of some pretty interesting historical differences between the two eras. The fundamental fact, ... but Pope Gregory was trying to do something harder - effectively to make the Gregorian calendar retrospective (proleptic) so that Easter would fall at the right time of year, and this required a calendrical jump of 11 days. A simple transition from the Julian leap year rule to the Gregorian rule (i.e. without calendrical discontinuity) would probably have been more saleable, especially to people with no interest in Easter. Mark Calabretta ATNF
Re: building consensus
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
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. Mark Calabretta ATNF
Re: building consensus
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: building consensus
In message: [EMAIL PROTECTED] John Cowan [EMAIL PROTECTED] writes: : Zefram scripsit: : : If this means that leap secounds 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. Leap seconds (after 1972) are closely analogous to irregularlly happening leap days. might be better, since leap days have a rule, while leap seconds are scheduled. : 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. 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... POSIX time_t definition effecitvely omits leap seconds from the time scale (by playing them twice, or pretending the second happened), the difference between two time_t's always gives a duration adjusted for the leap seconds that happen, rather than the actual duration. : 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. It would be better to say the number of SI seconds since 1972 rather than UTC seconds, I think. I use a timescale like this at work to ensure that duration calcuations over leap secondsd are correct. Warner
Re: building consensus
The answer to the intial query depends upon what you mean by active. Ron Beard, Chair of the ITU's Special Rapporteur Group is on the list. Also Dennis McCarthy, who is Chair of the IAU's Working Group on the Leap Second. I am less active, particucularly lately, but have been known to forward some emails around. We intentionally try to be silent in this forum. -Original Message- From: Leap Seconds Issues To: LEAPSECS@ROM.USNO.NAVY.MIL Sent: 06/01/2006 1:37 PM Subject: Re: [LEAPSECS] building consensus In message: [EMAIL PROTECTED] Rob Seaman [EMAIL PROTECTED] writes: : Warner Losh objects: : : 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. : : I have spent much time explaining why leap seconds cause real : problems in real applications, only to be insulted like this. : : Sincere apologies for my awkward statement. Dictionary.com defines : doughty as marked by stouthearted courage; brave. I wasn't : questioning the knowledge or passion of folks holding views that : differ from my own. Rather I was attempting to question whether : anybody actively participating on this list - holding whatever view - : is also participating in ITU discussions. : : I see that Mr. Cowan has also parsed my admittedly opaque remarks. Yes. I'm sorry I was so easily offended. Please accept my appologies for my hasty words. Warner
Re: building consensus
On Fri, 2 Jun 2006 [EMAIL PROTECTED] wrote: We intentionally try to be silent in this forum. Why? Peter.
building consensus
I've been reading the list archives. Parts of the discussion are rather repetetive. I think the search space could be narrowed quite a bit if the list produced a canonical statement of consensus, listing facts on which there is no dispute. This would serve much the same purpose as a FAQ, as well as possibly a base for a final report on the leap seconds issue. Let us grok in fullness before coming to a conclusion. So as a start here are some statements that I think are not controversial on this list. If any are disputed, please speak up. nature of time scales - UT1 et al are not really measures of time, but of angle (of Terran rotation). 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). 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. Readings of linear time scales (TT, TAI, et al) are most naturally represented as a real count of SI seconds since some epoch. 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. Readings of UTC cannot be directly represented by a single linear count. As a calendar, UTC is presently of the observational variety. civil time -- Up to the present, most human activity has been in the long term synchronised with local solar time. We are not in a position to determine whether, to what extent, and for how long, the synchronisation between activity periods of Terran humans and the rotation of the planet will be maintained. Up to the present, local civil time has approximately maintained a conventional correspondence with the timing of human activity. By the use of standard time zones, the correspondence between local civil time and local mean solar time has historically varied within a range of about five hours, excluding arctic regions. It is presently commonplace for the correspondence between local civil time and local mean solar time to vary periodically with an amplitude of one hour. It is convenient for the civil time in different localities to have a simple relationship. Where civil time involves a unit very close in duration to the SI second, it is convenient for that to actually be the SI second on the geoid. time handling in software - 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. The Unix time interfaces are capable of being used to correctly encode UT1, TAI, UTC-SLS, or other time scales that do not have internally-visible leap seconds. 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. 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. Some applications assume that Unix time encodes UTC, including discontinuous behaviour around leap seconds, and so would be poorly served by the encoding of anything other than UTC in Unix time. New applications need a more sophisticated understanding of time than is currently standard practice. Various applications require means to handle civil time, TAI, and UT1, among other time scales. Applications need to process times that are contemporary, historical, and in the foreseeable future, on all time scales they are interested in. When dealing with observational calendars and other unpredictable aspects of time scales, applications need a way to be sure that they have sufficiently fresh information about calendar structure. time dissemination -- Human society needs to develop better means to disseminate a multiplicity of time scales. -zefram
Re: building consensus
UT1 et al are not really measures of time, but of angle (of Terran rotation). To some degree yes, but don't they also include minor corrections (polar motion, longitude, etc.) and so at one level they already depart from raw angle measurement and instead are trying to act like clocks? /tvb
Re: building consensus
On Thu 2006-06-01T08:09:22 -0400, John Cowan hath writ: Some do, some don't, some couldn't care less. It deserves to be noted that last year at the GA in India URSI Commission J decided that it couldn't care, and discontinued its working group on the leap second. http://www.ursi.org/J_BusRepGA05.doc -- Steve Allen [EMAIL PROTECTED]WGS-84 (GPS) UCO/Lick ObservatoryNatural Sciences II, Room 165Lat +36.99858 University of CaliforniaVoice: +1 831 459 3046 Lng -122.06014 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
Re: building consensus
On Thu 2006-06-01T06:25:39 -0700, Tom Van Baak hath writ: UT1 et al are not really measures of time, but of angle (of Terran rotation). To some degree yes, but don't they also include minor corrections (polar motion, longitude, etc.) and so at one level they already depart from raw angle measurement and instead are trying to act like clocks? Yes. It is ironic that UT1 and UT2 were introduced in hopes of getting timeservices worldwide to finally start broadcasting time signals that agreed, but that because the observatories feeding the data to the broadcasters would not abandon the self-inconsistent values for their conventional longitudes (c.f. Janssen and Newcomb at the 1884 IMC) the signals did not start to agree until coordinated cesium clocks were in use. -- Steve Allen [EMAIL PROTECTED]WGS-84 (GPS) UCO/Lick ObservatoryNatural Sciences II, Room 165Lat +36.99858 University of CaliforniaVoice: +1 831 459 3046 Lng -122.06014 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
Re: building consensus
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. Warner
Re: building consensus
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
In message: [EMAIL PROTECTED] John Cowan [EMAIL PROTECTED] writes: : 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. Maybe I did misread them. I've been sick the past three days, so maybe we can chalk it up to that and I'll offer my oppologies for having such a thin skin. Wanrer
Re: building consensus
Warner Losh objects: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.I have spent much time explaining why leap seconds cause real problems in real applications, only to be insulted like this.Sincere apologies for my awkward statement. Dictionary.com defines "doughty" as "marked by stouthearted courage; brave". I wasn't questioning the knowledge or passion of folks holding views that differ from my own. Rather I was attempting to question whether anybody actively participating on this list - holding whatever view - is also participating in ITU discussions.I see that Mr. Cowan has also parsed my admittedly opaque remarks.RobNOAO
Re: building consensus
In message: [EMAIL PROTECTED] Rob Seaman [EMAIL PROTECTED] writes: : Warner Losh objects: : : 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. : : I have spent much time explaining why leap seconds cause real : problems in real applications, only to be insulted like this. : : Sincere apologies for my awkward statement. Dictionary.com defines : doughty as marked by stouthearted courage; brave. I wasn't : questioning the knowledge or passion of folks holding views that : differ from my own. Rather I was attempting to question whether : anybody actively participating on this list - holding whatever view - : is also participating in ITU discussions. : : I see that Mr. Cowan has also parsed my admittedly opaque remarks. Yes. I'm sorry I was so easily offended. Please accept my appologies for my hasty words. Warner
