Re: ITU Meeting last year
Steve Allen scripsit: > If there is something not clear in the presentation on > > http://www.ucolick.org/~sla/leapsecs/dutc.html > > I would be obliged to know about it. It's very clear and useful. But: > At Torino the proponents of omitting leap seconds supposed that the > governments of the world might handle this situation using leap hours > introduced into civil time by occasionally omitting the annual ``spring > forward'' change to jump to summer/daylight time. However there are > serious questions raised by the notion of a leap hour. Given that the > first leap hour would not happen for centuries, it is not clear that any > systems (legal or technological) would build in the necessary complexity > for handling it. Systems already have existing mechanisms for handling large secular changes in LCT. There are many places that adjust their daylight time mechanisms on a yearly basis anyhow. -- Where the wombat has walked,John Cowan <[EMAIL PROTECTED]> it will inevitably walk again. http://www.ccil.org/~cowan
Re: ITU Meeting last year
In message <[EMAIL PROTECTED]>, Steve Allen writes: >In the hopes of enlightenment for this list, but without the ability >to authenticate these draft documents, I offer the following: > >http://www.ucolick.org/~sla/leapsecs/SRG7Afinalreport.doc >http://www.ucolick.org/~sla/leapsecs/PropRevITU-RTF460-6.doc Looks good to me. >It seems that atomic clock keepers have lost all interest in the >continued existence of mean solar time, sundials, or the analemma. And why shouldn't they ? The job of atomic clock keepers is to keep TAI ticking. I really can't see any problem with the proposal above which even get into the same order of magnitude to the problems and inconvenience leapseconds are today. And I applaud them for setting a transition date which I think would spare us for even one more leap-second. As a private person living at 11°20'22.98" the sun is never in south at noon anyway and we have voluntarily moved it a further 15° away from south half the year already with daylights savings time. I already need to adjust my sundial twice a year anyway (OK, so I'm also at 55°N24' so it's not much use during winter so I don't actually bother but that's besides the point :-). As a computer nerd I can fully appreciate the problems and cost of converting existing systems to cope with larger UT1/UTC difference, but that cost would be peanuts compared to the costs of implementing leap-seconds reliably in future systems that would need it. And for that conversion cost: Just how hard is it to make a computer synchronize with NTP over the internet, pick the DUT1 up from IERS homepage and emit clocksignals which are UT1 approximations for those old computers anyway ? I know several operations computers here in Denmark which think it is 1985 because they cannot cope properly with years in a different century, people can live with that kind of quirk in old computers. Finally as goes with navigation, here in Denmark celestial navigation is now taught as a "historical interest" course... So yes, we might loose a ship or two if they for some reason rely on celestial navigation. Chances are very good that they were in dire straits already, otherwise they wouldn't have taken their eye off the GPS receiver and the radar long enough to locate the sekstant. Compare that to the number of deaths of just one major software bug triggered by a leapsecond, and things come into perspective nicely. -- 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: ITU Meeting last year
On Thu 2005-01-20T12:34:09 +, Clive D.W. Feather hath writ: > 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 -UTC offset forward by one hour, > in many cases by failing to implement the summer-to-winter step back. The text of the document from USWP 7A continues the trend that has been displayed publicly for several years now, namely that UTC would officially switch from leap seconds to leap hours. This is clearly an artifice, for there can be no expectation that people 5 centuries hence will respect the content of any revision of ITU-R TF.460 made today. It is not even clear that the BIPM is ready to respect it now. Looking at the players, however, a plausible reason for the artifice becomes clear. Many of the proposers are employees of agencies of the US Federal government. Under federal law the legal time of the United States is specified as "mean astronomical time", and in the parlance of the era of that legislation that clearly must be interpreted as the form of earth rotation time known as mean solar time. The most recent attempt to change the wording of the US Code failed. To propose the complete abolition of leaps would be to propose a time scale which demonstrably violates federal law. To propose leap hours is to propose an artifice which keeps the proposers from using their positions to advocate a violation of federal law. Legal fiction is a well-tested means of effecting change. It is hard to say what the actual intent is when so few documents have made it out of the inner sanctum of the Time Lords. In the hopes of enlightenment for this list, but without the ability to authenticate these draft documents, I offer the following: http://www.ucolick.org/~sla/leapsecs/SRG7Afinalreport.doc http://www.ucolick.org/~sla/leapsecs/PropRevITU-RTF460-6.doc It seems that atomic clock keepers have lost all interest in the continued existence of mean solar time, sundials, or the analemma. -- Steve Allen UCO/Lick Observatory Santa Cruz, CA 95064 [EMAIL PROTECTED] Voice: +1 831 459 3046 http://www.ucolick.org/~sla PGP: 1024/E46978C5 F6 78 D1 10 62 94 8F 2E49 89 0E FE 26 B4 14 93
Re: ITU Meeting last year
In message <[EMAIL PROTECTED]>, Steve Allen writes: >On Thu 2005-01-20T09:33:01 -0800, Tom Van Baak hath writ: >> So it's safe to say we're talking millennia rather >> than centuries, yes? I wonder where the notion >> that it's just a few centuries away came from. > >If there is something not clear in the presentation on > >http://www.ucolick.org/~sla/leapsecs/dutc.html I enjoyed your page a lot some time ago when I fell over it. Thanks a lot for the effort. -- 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: ITU Meeting last year
> It's not a linear curve, it's quadratic. I found some > slides from the torino meeting where this was laid out very > well but I didn't save the URL, sorry. Ah, yes, I forgot the quadratic term. Steve Allen has a nice page at: http://www.ucolick.org/~sla/leapsecs/dutc.html And his table shows the first leap hour would occur in the year 2500 to 2600 time frame. So that's where the 500 or 600 year value people quote comes from; it's a few centuries from now, not millennia afterall. Thanks, /tvb http://www.LeapSecond.com
Re: ITU Meeting last year
On Thu 2005-01-20T09:33:01 -0800, Tom Van Baak hath writ: > So it's safe to say we're talking millennia rather > than centuries, yes? I wonder where the notion > that it's just a few centuries away came from. If there is something not clear in the presentation on http://www.ucolick.org/~sla/leapsecs/dutc.html I would be obliged to know about it. -- Steve Allen UCO/Lick Observatory Santa Cruz, CA 95064 [EMAIL PROTECTED] Voice: +1 831 459 3046 http://www.ucolick.org/~sla PGP: 1024/E46978C5 F6 78 D1 10 62 94 8F 2E49 89 0E FE 26 B4 14 93
Re: ITU Meeting last year
In message <[EMAIL PROTECTED]>, Tom Van Baak writes: >If one uses the rough but often-quoted figure of >"one leap second about every 500 days" then >a leap hour would be required on the order of >500 * 3600 / 365 = ~5000 years from now. It's not a linear curve, it's quadratic. I found some slides from the torino meeting where this was laid out very well but I didn't save the URL, sorry. -- 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: ITU Meeting last year
> As seen on my online bibliography web page, the proposal probably was > a slightly evolved form of this document > > http://www.fcc.gov/ib/sand/irb/weritacrnc/archives/nc1893wp7a/1.doc No one can know for sure but I was wondering if there is a consensus on when the first leap hour would occur? Even to an order of magnitude? I ask because the above document draft says "at least 500 years" while others here cite numbers like 600 years, or 5000 years. If one uses the rough but often-quoted figure of "one leap second about every 500 days" then a leap hour would be required on the order of 500 * 3600 / 365 = ~5000 years from now. So it's safe to say we're talking millennia rather than centuries, yes? I wonder where the notion that it's just a few centuries away came from. /tvb http://www.LeapSecond.com
Re: ITU Meeting last year
In message <[EMAIL PROTECTED]>, John Cowan writes: >Markus Kuhn scripsit: > >> In my eyes, a UTC leap hour is an unrealistic phantasy. I think your critizism of it is just as unrealistic. If 600 years down the road we have colonized the solar system, then a large fraction of the population wouldn't care about terrestial solar time anyway, and I'm sure the leap hour will be cancled well in advance. Given that the average western citizen under 30 years already today can barely add up three items in the supermarket without resorting to their mobile phones built in calculator today, I think you can safely assume that you can do anything to the timescale 100 years from now. At that time most people will just as they're told on television (probably in 3D and with full olfactory support) and the few scientists who care will be bogged down in a very theoretical discussion about what it would have done to the cows milk, had cows not been outlawed for foodstuff production many years ago. Considering that the last couple of changes to our timescales were forced through in very short time, say 20 years to be very generous then we can change our timescales 130 times between now and the first leap-hour, and that is provided earthquakes and yet unknown geophysics don't make them unnecessary or make it more necessary. We certainly don't need to decide now who is going to call the leap hour 600 years from now, all we need to decided is who gets to call it as long as the next treaty on time is in force. If that turns out to be 600 years, then it stands for 600 years, if ten years from now we find out what the real nature of time is and need to make a new timescale, then somebody had an easy job for 10 years. The one thing we don't need is flaming rethoric... -- 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: ITU Meeting last year
On Thu 2005-01-20T13:39:58 +, Markus Kuhn hath writ: > That was certainly the idea of the BIPM proposal presented at the Torino > meeting. As seen on my online bibliography web page, the proposal probably was a slightly evolved form of this document http://www.fcc.gov/ib/sand/irb/weritacrnc/archives/nc1893wp7a/1.doc -- Steve Allen UCO/Lick Observatory Santa Cruz, CA 95064 [EMAIL PROTECTED] Voice: +1 831 459 3046 http://www.ucolick.org/~sla PGP: 1024/E46978C5 F6 78 D1 10 62 94 8F 2E49 89 0E FE 26 B4 14 93
Re: ITU Meeting last year
"Clive D.W. Feather" wrote on 2005-01-20 12:34 UTC: > >> 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. > > I may be wrong here, but I thought the "leap hour" idea did *not* insert a > discontinuity into UTC. I think, the phrase "to redefine UTC by replacing leap seconds by leap hours" can only mean going from |UTC - UT1| < 1 s to something like |UTC - UT1| < 1 h (or some other finite |UTC - UT1| bound like that). That was certainly the idea of the BIPM proposal presented at the Torino meeting. > Rather, in 2600 (or whenever it is), all civil > administrations would move their -UTC offset forward by one hour, > in many cases by failing to implement the summer-to-winter step back. Such a proposal would be called "to redefine UTC by eliminating future leaps" (i.e., by establishing a fixed offset between UTC and TAI). It seems perfectly practical, at least as long as |UTC - UT1| < 24 h (i.e., for the next 5000 years). What local governments with regional civilian time zones do is outside the influence of the ITU. But if leap seconds were eliminated from UTC and a fixed TAI-UTC offset defined instead, then what you describe above is indeed what I would expect to happen with most of them. Unless we give up the notion of local time zones entirely, there would be a clear need to keep them locked to UT1 + offset to within an hour or so. Markus -- Markus Kuhn, Computer Lab, Univ of Cambridge, GB http://www.cl.cam.ac.uk/~mgk25/ | __oo_O..O_oo__
Re: ITU Meeting last year
Clive D.W. Feather scripsit: > 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. For that matter, Newfoundland could decide to change its offset from the current -0330 to -0300 in 2300, and then leave it alone until 2900. The world would spin on quite unaffected. (Newfie joke suppressed here.) -- John Cowan [EMAIL PROTECTED] http://www.reutershealth.comhttp://www.ccil.org/~cowan Humpty Dump Dublin squeaks through his norse Humpty Dump Dublin hath a horrible vorse But for all his kinks English / And his irismanx brogues Humpty Dump Dublin's grandada of all rogues. --Cousin James
Re: ITU Meeting last year
Markus Kuhn scripsit: > In my eyes, a UTC leap hour is an unrealistic phantasy. I agree. But the same effects can be achieved by waiting for local jurisdictions to change the existing LCT offsets as the problem becomes locally serious. They've done it many times in the past and can easily do so again. The fact that America/New_York is either five or four hours behind UTC is not carved in stone anywhere, it's just what happens to work right now. A change to being either four or three hours behind will not have nearly the same disruptive effect as a disruption in UTC. And perhaps people won't even bother. If people in Urumqi right now can tolerate a three-hour difference between LMT and LCT, a slightly different relation between the sun and the clock may seem quite tolerable to our great^20-grandchildren. (Astronomers will howl. They doubtless howled when we broke the connection between the calendar and the synodic month, too. IERS can even maintain OldUTC for their benefit; what matters is what the basis of LCT is, since we all live our lives primarily by LCT.) -- In politics, obedience and support John Cowan <[EMAIL PROTECTED]> are the same thing. --Hannah Arendthttp://www.ccil.org/~cowan
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 -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: ITU Meeting last year
[EMAIL PROTECTED] wrote on 2005-01-19 20:19 UTC: > 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. Thanks for the update! Did the proposed resolution contain any detailed political provisions that specify, who exactly would be in charge of declaring in about six centuries time, when exactly the first UTC leap hour should take place? Will IERS send out, twice a year, bulletins for the next *600 years*, announcing just that UTC will continue as usual for the next 6 months? Not the most interesting mailing list to be on ... And when the day comes, will people still recognize the authority of IERS and ITU in such matters? Keep in mind that the names, identities, and structures of these instritutions will likely have changed several times by then. Also keep in mind that any living memory of the last UTC leap will then have been lost over twenty generations earlier. The subject won't get any less obscure by making the event a 3600x more rare occasion. 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. Judging from how long it took to settle the last adjusting disruption of that scope (the skipping of 10 leap days as part of the Gregorian calendar reform), I would expect the UTC leap hour to become either very messy, or to never happen at all. Who will be the equivalent of Pope Gregory XIII at about 2600 and where would this person get the authority from to break thoroughly what was meant to be an interrupt-free computer time scale. Even the, at the time, almightly Catholic Church wasn't able to implement the Gregorian transition smoothly by simply decreeing it. Do we rely on some dictator vastly more powerful than a 16-th century pope to be around near the years 2600, 3100, 3500, 3800, 4100, 4300, etc. to get the then necessary UTC leap hour implemented? Remember that UTC is used today widely in computers first of all because it *lacks* the very troublesome DST leap hours of civilian time zones. Most of the existing and proposed workarounds for leap seconds (e.g., smoothing out the phase jump by a small temporary frequency shift) are entirely impractical for leap hours. Please shoot down this leap-hour idea. The problem is not solved by replacing frequent tiny disruptions with rare catastrophic ones. It is hardly ethical to first accept that a regular correction is necessary, but then to sweep it under the carpet for centuries, expecting the resulting mess to be sorted out by our descendents two dozen generations later on. Leap hours are 3600 more disruptive than leap seconds! If ITU wants to turn UTC into an interrupt-free physical time scale decoupled from the rotation of the Earth, then it should say so honestly, by defining that UTC will *never* ever leap in any way, neither by a second, nor by an hour. Markus -- Markus Kuhn, Computer Lab, Univ of Cambridge, GB http://www.cl.cam.ac.uk/~mgk25/ | __oo_O..O_oo__
ITU Meeting last year
This is a very brief description of what happened at last October's ITU meeting in Geneva. 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. This proposal was not passed, but remains under active consideration. Presumably something like it will be considered next year. My quick computation indicates that, should this proposal be adopted, it would take about a century for UT1-UTC to diverge by one minute, and many centuries before a leap-hour would be called for. I did not attend the meeting, and this is all I know. I was told the ITU web pages had essentially this same information in them, but could not find anything there with their search engine.
