Re: Introduction of long term scheduling
Rob Seaman said: Feather's encoding is a type of compression. GZIP won't buy you anything extra. Actually, it might with longer tables. For example, LZW (as used by Unix compress) can be further compressed using a Huffman-based compressor. I'll join the rising chorus that thinks it need not appear in every packet. Phew. I'd also modify Feather encoding to delta backwards from the expiration time stamp. Interesting idea. -- 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: Introduction of long term scheduling
Rob Seaman said: Which raises the question of how concisely one can express a leap second table. Firstly, I agree with Steve when he asks why bother?. You're solving the wrong problem. However, having said that: So, let's see - assume: 1) all 20th century leap seconds can be statically linked 2) start counting months at 2000-01-31 We're seeing about 7 leapseconds per decade on average, round up to 10 to allow for a few decades worth of quadratic acceleration (less important for the next couple of centuries than geophysical noise). So 100 short integers should suffice for the next century and a kilobyte likely for the next 500 years. Add one short for the expiration date, and a zero short word for an end of record stopper and distribute it as a variable length record - quite terse for the next few decades. The current table would be six bytes (suggest network byte order): 0042 003C That's far too verbose a format. Firstly, once you've seen the value 003C, you know all subsequent values will be greater. So why not delta encode them (i.e. each entry is the number of months since the previous leap second)? If you assume that leap seconds will be no more than 255 months apart, then you only need one byte per leap second. But you don't even need that assumption: a value of 255 can mean 255 months without a leap second (I'm assuming we're reserving 0 for end-of-list). But we can do better. At present leap seconds come at 6 month boundaries. So let's encode using 4 bit codons: * Start with the unit size being 6 months. * A codon of 1 to 15 means the next leap second is N units after the previous one. * A codon of 0 is followed by a second codon: - 1, 3, 6, or 12 sets the unit size; - 0 means the next item is the expiry date, after which the list ends (this assumes the expiry is after the last leap second; I wasn't clear if you expect that always to be the case); - 15 means 15 units without a leap second; - other values are reserved for future expansion. So the present table is A001. Two bytes instead of six. If we used 1980 as the base instead of 2000, the table would be: 3224 5423 2233 3E00 1x where the last byte can have any value for the last 4 bits. I'm sure that some real thought could compress the data even more; based on leap second history, 3 byte codons would probably be better than 4. -- 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: Mechanism to provide tai-utc.dat locally
M. Warner Losh said: time_t is so totally broken, it isn't funny. That's the closest thing to a standardized API there is for time. All others are stuff folks have done here or there, but they aren't universal enough to be considered. Too bad the problems with time_t are well known, well discussed and well enumerated. Or rather I should say too bad POSIX doesn't care enough to change it since the cost of changing time_t is huge... Not so. POSIX in the past deferred to WG14 (the ISO C committee) because that's where time_t came from. WG14 is willing in principle to make changes to time_t, up to and including completely replacing it by something else. *BUT* it needs a complete and consistent proposal and, preferably, experience with it. Any proposal has got to deal with a whole load of issues, many of which haven't been properly documented. For example, it should be possible to add and subtract times and intervals (e.g. what time is 14 months and 87 days from now?). -- 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: Titan Time
Zefram said: There's nothing at all wrong with the radian - but there is a reason calculators let you switch between degrees and radians. Each is best for particular purposes, Certainly the radian is best for some purposes. But the degree? Is there some inherent feature of the circle that makes it particularly natural to divide it into 360 parts? Not really. Personally, I like the mil: 6400 mils in a circle, and a mil is close enough to a milliradian that you can use the usual tricks (a mil subtends about a metre at a kilometre). -- 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: the case for created time
Rob Seaman said: We have all been so utterly wrong! The scales drop from my eyes (http://www.creation-answers.com): A theory of evolution for the creation of the solar system seems less than satisfactory in regard that the Earth and Moon appear to generate interrelated time cycles. A prize (well, a beer when next we meet) to the best explanation of what the heck this guy is on about... He's another numerologist, finding patterns and coincidences in numbers (something that will always appear if you keep looking) and trying to claim they are significant. For example, if you look at: http://www.creation-answers.com/system.htm he finds great interest in the fact that 50 years is approximately (50*7*7 + 7)/4 lunar months [1], tying this into biblical rules about a 7*7+1 economic cycle. Similarly, 49 lunar months are almost exactly 1447 days. From these coincidences he assumes that the system must have been designed and created. He then assumes that the slight differences are proof of a golden past when the numbers were exact. Typical creationist reverse logic. [1] Except it's not - he's about 4 lunar months out, which he fudges through a triennial leap 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
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
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
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: 24:00 versus 00:00
Markus Kuhn said: Writing 24:00 to terminate a time interval at exactly midnight is pretty common practice and is even sanctioned by ISO 8601. See for example the railway timetable on http://en.wikipedia.org/wiki/24-hour_clock where trains arrive at 24:00 but depart at 00:00. Usual UK railway practice is to use 00:00 throughout in timetables, including internal ones. 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). -- 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: Risks of change to UTC
M. Warner Losh said: 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. Why not? Greek and Latin, to name two, were spoken that long ago and are recognisable today. And the English of 1000 years ago is still an official language of the Netherlands (under the name Frisian). -- 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: the tail wags the dog
Steve Allen said: The official time of the US for commerce and legal purposes is UTC(NIST). The official time of the US DOD is UTC(USNO). The official time of the Federal Republic of Germany is UTC(PTB). etc. The official time of the UK is GMT. -- 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: Fixing POSIX time
Neal McBurnett said: UT1:Flamsteads birthday ? Cute. 1646-08-19 O.S. or N.S.? At least it wasn't January, which would have added a third option. -- 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: interoperability
Rob Seaman said: The question of delivering wall clock time is a trivial elaboration on first delivering common international business time. (I'm trying on different terminology than civil time until I hit one that sticks.) I don't accept that the concept exists. The international business community still works - as far as I can tell - on the equivalent of Hello Fred, what time is it there?. The event of migrating a time zone is a discontinuity just as with a leap second or leap hour. So what? We go through such discontinuities twice a year in most years. Some places more often. Read the TZ list archives. What matters is not when sunrise occurs, but rather that every day has one (and only one). Something which isn't and hasn't been true in many places. What time is sunrise in Tromso today? What time was sunrise on 1994-12-31 in eastern Kiribati? If Denmark or Elbonia decides to use a timezone which is offset from stage one by 1h3m21s, then it still works, Again, what is it, precisely? Life. (but people travelling abroad will probably vote differently in the next election) Exactly. The pressures to maintain a common international vision of time will trump local variations. That's not pressure to maintain a common international vision, but people not wanting to fiddle with the minutes and seconds on their digital watches. In a couple of hundred years, the Danish Parliament (or its successor in interest) will simply decide from -MM-DD HH:00, the Danish Civil time will use offsets -3h and -2h (instead of presently -1h/-2h) and the transition will happen on the switch from summertime to wintertime by _not_ adjusting the clock. The only way this differs from the leap hour proposal is that you are assuming that different localities can (or would) carry these adjustments out separately. Let's see - how does this work? Just the way that it does right now. Under the current standard, 3600 small steps would have bled away the pressure. Under the ITU notion, a leap hour would be needed. A leap hour means moving UTC backward one hour (to let TAI pull ahead). As I've said before, under the daylight saving analogy this is only naively a fall back event, it would be better to explicitly add a 25th hour. But let's continue through to the logical conclusion of implementing this via fall back events (or the equivalent time zone shifting). Except that time zone shifting means you don't affect the UTC sequence. A fall back event means that the clock (local, standard, international, whatever clock you want) first traverses an hour - and then traverses it again. Right. At present, there's a meridian corresponding to UTC that starts at Greenwich, drifts back and forth with secular changes in the earth's rotation and, when it approaches Cutty Sark or the Dome suddenly jumps. The proposal is simply to have this jump abolished, so that the UTC meridian starts drifting around the earth. Um. How does one redefine the length of the day without changing the length of the second? Answer: by changing the number of seconds in the day. I won't belabor the difficulty of selling the idea of having different hours of different lengths. You mean just like now? -- Clive D.W. Feather | Work: [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: interoperability
Rob Seaman said: I have heard no response to my discussion of techniques for achieving synchronization - of the difference between naive fall back hours and 25 hour days. But how in practice is it envisaged that a scheme for migrating time zones versus TAI would work, precisely? In the short term, by modifying the UTC-LTC function by adding a secular term to the periodic one. Thus at present the function in the UK is: dayofyear in [Last Sunday in Mar .. Last Sunday in Oct] ? 3600 : 0. This would change to: (dayofyear in [Last Sunday in Mar .. Last Sunday in Oct] ? 3600 : 0) + (year 2600 ? 0 : year 3100 ? 3600 : year 3500 ? 7200 : ...) or whatever. Note that we already have similar levels of complexity in dealing with the changing summer time dates, the British Standard Time folly, BDST during the war, and so on. Note also that the Olsen tz code handles all of this just fine. Note, for instance, that nothing short of redefining the second can avoid the quadratic acceleration between the stage one and stage two clocks. Time zones (and the prime meridian?) would race more-and-more rapidly around the globe. At some point, probably around the time that we're seeing an hourly shift every year, people are going to have to divorce second from day, or at least re-negotiate the terms of engagement. -- 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: The real problem with leap seconds
I wrote: Right now, the DTAI(TAI) function is the sum of a set of Kroneker delta functions. Thanks to David for quietly pointing out that I meant Heaviside step functions, not Kroneker delta functions. -- 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: The real problem with leap seconds
Poul-Henning Kamp said: So the standards crew, POSIX, LSB or whoever would have to come up with a new data type for holding timestamps, We already have one: struct tm. There is no doubt that from a humanistic point of view it would be better to educate all the programmers, but considering that I still suffer from web-forms that insist I enter a USA style phone number when I have entered Denmark as country, this is a far moure daunting task than it might appear. Amen. [I happen to have a US Social Security number, which allows me to confuse some web pages back.] -- 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: civil time = solar time
Rob Seaman said: 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. Only *very* *very* approximately. In the UK, sunset varies from about 15:30 to about 22:30 LCT. Sunrise isn't an event most people even care about (for me, it shifts from happens at work to happens before I get up on an annual basis but, during the winter, on a weekly basis as well). Provided that astronomical noon is between about 08:00 and 16:00, most people won't care. For unless they see the sky, But they can't, and that is why They know not if it's dark outside or light. -- 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: Longer leap second notice
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. -- 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: Lighter Evenings (Experiment) Bill [HL]
Poul-Henning Kamp said: Not strictly on topic but probably of interest - a Bill in the UK House of Lords which I just came across when looking for something else: A Bill To Advance time by one hour throughout the year for an experimental period; and for connected purposes. the entire notion and I belive the welch are not too happy either. Not if you call them that! -- 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: a system that fails spectacularly
Steve Allen said: This became a long-running joke in the morris dance community. A few years back some English town councils decided to become ISO 9000 compliant. That required them to ascertain that all of their sub-contractors were also compliant. Actually, it does nothing of the sort. An organisation going for qualification must set up an ISO 9000 boundary. Everything inside must conform to the processes, so anything coming in through the boundary must be assessed each time it comes in. The boundary can go around more than one organisation. So many organisations find it easier to force their suppliers and sub-contractors inside the boundary than to deal with stuff coming in. In other words, it's easier to only buy widgets from ISO 9000 compliant suppliers than to provide an inbound widget quality test department. -- 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: a system that fails spectacularly
M. Warner Losh said: * A second is represented by an integer from 0 to 61; [...] but this specification follows the date and time conventions for ISO C. Of course, ISO C fixed this misunderstanding many years ago. -- 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: BBC - Leap second talks are postponed
John.Cowan said: GMT is, unfotunately, widely used to mean the time in Britain during winter. Indeed, it is sometimes used to mean that even in the summer. There was some confusion in my company last year about a teleconference scheduled in GMT which turned out to actually refer to British Summer Time. Microsoft *spit* Outlook calendar management talks about GMT Daylight Savings Time or some such idiocy. Every spring I respond to the first appointment request from my boss with so do you want to meet at 10:00 GMT or 10:00 BST?. -- 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: Consensus rather than compromise
John.Cowan said: Rather, the very definition of civil time was misunderstood, whether by Microsoft or by somebody else. I think this greatly overstates the case. Exactly. There was a mere misapplication of labels involved, both in the case of the conference leader (who believes that the name GMT refers to the LCT of the U.K.) Which is a relatively rare belief, easily countered by (for example) looking at the BBC news web site. and the anonymous Microsoft programmer (who believes that British Summer Time should be called GMT Daylight Time). Exactly. The belief that the T means Time, therefore it's subject to DST. I wonder if it mishandles zones near the equator which don't have DST? Neither are to do with the *definition* of civil time [1], but with its name. [1] Microsoft has been known to get this wrong as well, attempting to apply US rules to the EU. -- 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: Consensus rather than compromise
Rob Seaman said: The problem here is Microsoft, whose software appears to believe that the current LCT here is GMT Daylight Time. The case has been repeatedly made that since the world tolerates large excursions in civil time such as caused by the varying local Daylight Saving Time policies, and by these policies changing, sometimes on short notice, yes. that the world's institutions and populace will be able to simply ignore leap hours on those rare occasions when they are needed. What is offered up is evidence for the exact opposite. False. We're shown that Daylight Saving has been mishandled in a trivially simple instance and that the GMT standard, synonymous with UTC, is capable of misinterpretation (by minions of the richest man on Earth) completely distinct from leap second related issues. No, it appears that a few people think that the GMT standard is synonymous with UK local time. This is just as much a fallacy as the belief that Indiana currently observes US Central Time. And, by the way, the GMT standard is *NOT* synonymous with UTC; it is (IIRC) UT1. Nothing about the ITU proposal would mitigate the situation being discussed. True. Nor would it mitigate the Indiana problem. Nor, incidentally, would it harm either. It would be the constant daily persistence of a large DUT1 that would make leap hours unpalatable Why? Apart from astronomers, of course, who actually cares what the value of DUT1 is? Consider the value DLCT (LCT-UTC). This varies between -1 and 3601 over the year, yet the only effect it has is that it varies whether or not I have to turn on the car headlights on the way to work. And if civilians are surprised by the requirements of civil time now, how much more so they will be in a world in which the last leap hour troubled their great-great-...-great-grandparents? Yet they cope with the complex proposals to move counties of Indiana between zones, or to move DST end-dates every decade or so. We coped with the introduction of British Standard Time and its abolition. I suggest that fiddling with the hourly shifts will continue every few years ad nauseam, so one more reason for doing so won't bother anyone. Contrast this with a well-formed consensus - several disagreeing factions are locked in a room until they all agree on a common vision of how to proceed. Call this the Twelve Angry Men effect. That one faction or another may have to completely change their original position is a strength, not a weakness. Ideally none of the factions even arrives in the room with a specific position to bargain over, but rather arrives only with general requirements and objectives. That works when it works. Not when there are irreconcilable differences in the general requirements and objectives. What is needed is civil time to continue to reflect solar time as it has since literally the dawn of time. Within a couple of hours plus or minus. -- 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: Precise time over time
Poul-Henning Kamp said: As I said, 50 years seems right, and it does so because there is no currently running computer that has worked for 50 years. Actually, the programme machines that control the signalling of much of the London Underground are somewhat older than that. They run to, IIRC, a 15 second accuracy (I'd have to dig out various technical papers to be sure). In the US I belive something is antique when it is 25 years old, in Europe I think it has to be 50 years old to gain the distinction. 100 years. -- 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: GMT - UTC in Australia
Rob Seaman said: No reasonable standard can be based on constraining the behavior of our descendants 600 years hence. In what way is the requirement |DUT| = 0.9s not constraining the behaviour of our descendants 600 years hence? While I understand your argument about the name UTC: * *EVERY* approach requires constraining the behaviour of our descendants 600 years hence, just in different ways; * Universal Time is a *really* stupid name for a time scale based on the variable rotations of one small piece of rock. -- 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: our customers' needs
Rob Seaman said: Our modern sensibility may lead us to discount Egyptian and Druidic (or earlier) world views, but surely the many cultures worldwide that produced pyramids and other monolithic structures do demonstrate the frequent centrality of spirituality in human decision making. Those cultures most definitely knew the motions of the Sun, Moon, stars and planets intimately. Steve Allen already provided a convincing real world example of the response of a more recent mainstream religious community to civil calendar issues. This would be the point about sunrise on saints' days? All these issues have one thing in common - they pre-date the introduction of atomic time, but rather date back to when mean solar time was assumed to be constant rate and therefore unchanging. What, I wonder, did the various churches do about the Eleven Days? They can hardly have been taken down and rebuilt at a slight angle, after all. At this critical point in world history, what possible justification could there be for truncating the discovery process for uncovering similar requirements placed on civil time by the great religions of the world before making a large change in the definition of civil time? I have no problem with trying to identify the issues involved. But we can reasonably ask whether the alignment of a few buildings in Oxfordshire [*] is grounds for forcing the whole world to cope with the kludge of leap seconds for the next thousand years. [* Usual Cambridge-Oxford rivalry deleted for brevity.] -- 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||
Crustal rebound
Markus Kuhn said: The US and UK are actually no different from that, except that the subtle differences between GMT and UTC have escaped political attention in these two countries so far, and as a result, they still have a technically rather vague definition of time in their law books, Actually, UK law is clear that civil time is GMT/GMT+1. Last night I found myself talking to a UK legislator on the matter of UTC versus GMT. We got as far as the quadratic nature of the TAI-UT1 difference, and that it was smaller than expected because - according to my reading - of crustal rebound following the last ice age. At which point we were both confused about the physics involved. If the crust is rebounding after being compressed by ice sheets, surely the earth's moment of inertia will increase and the rotation should slow *more* than otherwise expected. So can someone unconfuse us, please? -- 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: ITU Meeting last year
Markus Kuhn said: A resolution was proposed to redefine UTC by replacing leap seconds by leap hours, effective at a specific date which I believe was something like 2020. [...] If this proposal gets accepted, then someone will have to shoulder the burden and take responsibility for a gigantic disruption in the global^Wsolar IT infrastructure sometimes around 2600. I believe, the worry about Y2K was nothing in comparison to the troubles caused by a UTC leap hour. We certainly couldn't insert a leap hour into UTC today. In my eyes, a UTC leap hour is an unrealistic phantasy. [...] I may be wrong here, but I thought the leap hour idea did *not* insert a discontinuity into UTC. Rather, in 2600 (or whenever it is), all civil administrations would move their local-UTC offset forward by one hour, in many cases by failing to implement the summer-to-winter step back. Thus in the UK and the US eastern seaboard, the civil time would go: UK US east Summer 2599: UTC + 0100UTC - 0400 Winter 2599/2600: UTC + UTC - 0500 Summer 2600: UTC + 0100UTC - 0400 Winter 2600/2601: UTC + 0100UTC - 0400 Summer 2601: UTC + 0200UTC - 0300 Winter 2601/2602: UTC + 0200UTC - 0400 That *is* practical to implement, though coordination might be harder. On the other hand, adminstrative areas that are near the edge of a zone now could move earlier if they wanted. The world is used to time zones, after all. -- 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: more media coverage
Steve Allen said: CNN is broadcasting the video form of this story today http://www.cnn.com/2003/WORLD/europe/07/22/time.boulden/index.html I surmise that Mr. Catchpole was not prepared with the figures. He also seems to be unaware of the legal status of GMT in the UK. [Incidentally, if I recall correctly the building at Greenwich is now just a museum, with the RGO having been abolished.] -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet Expert | Home: [EMAIL PROTECTED] | *** NOTE CHANGE *** Demon Internet | WWW: http://www.davros.org | Fax:+44 870 051 9937 Thus plc|| Mobile: +44 7973 377646
Re: What problems do leap seconds *really* create?
John Cowan said: Fact 2 is that the old 1980s pre-POSIX Unix manuals talked about GMT and not UTC. This strongly suggests that the authors were unfamiliar with both TAI and UTC. The seconds they refer to behave more like UT1 seconds than like TAI/SI seconds, i.e. they are Earth rotation angles and not Caesium oscillations. Where do you see any reference in the old documentation to the rotation of the Earth? The authors of those man pages were engineers, and they knew perfectly well what a second was and is (since 1967), and they certainly knew the difference between measuring/counting and encoding. I was around, though on the margins, when the first POSIX standard was being written. If there had been an awareness of the difference between UTC and GMT, I am the sort of person who would have leaped on it in an attempt to win a Weirdnix prize. I offer this as weak evidence in support of Marcus - nobody was discussing stuff at this level of detail. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel: +44 20 8371 1138 Internet Expert | Home: [EMAIL PROTECTED] | Fax: +44 870 051 9937 Demon Internet | WWW: http://www.davros.org | Mobile: +44 7973 377646 Thus plc||
