Re: [LEAPSECS] What's the point?
On Wed 2011/02/16 01:34:57 -, Tony Finch wrote in a message to: Leap Second Discussion List leapsecs@leapsecond.com I have been saying that, as a reason for changing UTC today, it is a specious argument that should be rejected. Yes. Agreement! It's also a bogus argument for keeping leap seconds. If anyone were to make that argument. Regards, Mark Calabretta ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 15 Feb 2011, at 05:46, Rob Seaman wrote: Combining these improved predictions with prudently relaxed DUT1 constraints should permit extending leap second scheduling to several years. These steps can be taken today with no tedious international negotiations. The UK's standard time broadcast, which is funded by the government, contains DUT1 in a format which doesn't permit |DUT1|0.9.Whatever people argue (rightly) about the de facto legal time in the UK being UTC, the de jure legal time is GMT which is taken to be UT1. It's somewhat difficult to see how to resolve that: MSF has to broadcast UK legal time, and there are huge amounts of equipment that grok the format it broadcasts. As to how much of that uses DUT1 is unknown, but whatever you do to fit a large |DUT1| into the format it has to avoid breaking devices which don't use it. Deciding to not broadcast an accurate DUT1 is a technical option, but it would have legal ramifications. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message 8e992e8a-cc16-44ec-a73e-e569d9395...@batten.eu.org, Ian Batten wri tes: The UK's standard time broadcast, which is funded by the government, contains DUT1 in a format which doesn't permit |DUT1|0.9.Whatever people argue (rightly) about the de facto legal time in the UK being UTC, the de jure legal time is GMT which is taken to be UT1. Where and by who is that taken to be UT1 ? Just because the additional DUT information is broadcast is no guarantee that any decodes it and uses it. And I certainly do not see a DUT offset between NTP servers in the rest of the world and NTP servers in the UK. You will need to document this claim before anybody will buy it, and I am quite sure that if you can, a lot of people will be very surprised... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Poul-Henning Kamp said: The UK's standard time broadcast, which is funded by the government, contains DUT1 in a format which doesn't permit |DUT1|0.9.Whatever people argue (rightly) about the de facto legal time in the UK being UTC, the de jure legal time is GMT which is taken to be UT1. Where and by who is that taken to be UT1 ? Just about everyone. Since GMT well predates the invention of UTC, it can't be anything other than UT, UT1, or UT2. Just because the additional DUT information is broadcast is no guarantee that any decodes it and uses it. True but irrelevant. And I certainly do not see a DUT offset between NTP servers in the rest of the world and NTP servers in the UK. Because those NTP servers provide UTC-with-leap-second-issues, not UT1, just like the ones in the rest of the world. Curiously enough, NTP is *NOT* the definition of legal time in the UK. You will need to document this claim before anybody will buy it, Which one? That GMT = UTC? That legal time is GMT? and I am quite sure that if you can, a lot of people will be very surprised... Well, as to the latter, the 1978 law says: | Subject to section 3 of the Summer Time Act 1972 (construction of | references to points of time during the period of summer time), whenever an | expression of time occurs in an Act, the time referred to shall, unless it | is otherwise specifically stated, be held to be Greenwich mean time. This is almost certainly a tidying up of older legislation in the same wording, but I don't have quick access to that. The Summer Time Act 1972 says: | 1(1) The time for general purposes in Great Britain shall, during the | period of summer time, be one hour in advance of Greenwich mean time. | (2) The period of summer time for the purposes of this Act is the period | beginning at one o'clock, Greenwich mean time, in the morning of the last | Sunday in March and ending at one o'clock, Greenwich mean time, in the | morning of the last Sunday in October. | | 3(1) Subject to subsection (2) below, wherever any reference to a point | of time occurs in any enactment, Order in Council, order, regulation, | rule, byelaw, deed, notice or other document whatsoever, the time referred | to shall, during the period of summer time, be taken to be the time as | fixed for general purposes by this Act. | (2) Nothing in this Act shall affect the use of Greenwich mean time for | purposes of astronomy, meteorology, or navigation, or affect the | construction of any document mentioning or referring to a point of time in | connection with any of those purposes. The 1954 legislation for Northern Ireland says: | Words in an enactment relating to time and references therein to a point of | time shall be construed as relating or referring to Greenwich mean time, | subject, however, to any statutory provision which may for the time being | provide that, during any specified period or periods, time in Northern | Ireland is to differ from Greenwich mean time. -- Clive D.W. Feather | If you lie to the compiler, Email: cl...@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646 ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message 20110215100536.gd78...@davros.org, Clive D.W. Feather writes: Poul-Henning Kamp said: The UK's standard time broadcast, which is funded by the government, contains DUT1 in a format which doesn't permit |DUT1|0.9.Whatever people argue (rightly) about the de facto legal time in the UK being UTC, the de jure legal time is GMT which is taken to be UT1. Where and by who is that taken to be UT1 ? Just about everyone. Really ? In that case, please provide us with 10 examples of everyone. Specifically, provide us with the identity of 10 independent of each other companies, agencies or organizations, who are willing to put in writing, and have done so, that they expect GMT to be UT1 rather than UTC. Until you have this, please stop spewing nonsense... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Poul-Henning Kamp said: Mean Solar Time = UT1 = GMT: So everybody using NTP and deriving GMT withut applying DUT are in breach of the law ? They're simply getting it wrong. The law doesn't require the use of GMT for everything; it just defines what legal time is. If it came to a lawsuit over the exact time that something happened relative to a statutory boundary, then such an NTP server would not be good evidence. Compare Curtis v March [1858] 3 HN 866. I bet more people would be surprised and in violation, than you will find in compliance... For one thing, all the Rugby receiving radio-controlled clocks do not apply the DUT bits... If those clocks were being sold as GMT clock or UK legal time clock, then the seller would be in breach of the Sale of Goods Act. But I don't believe they are; they're just sold as self-synchronizing to MSF. -- Clive D.W. Feather | If you lie to the compiler, Email: cl...@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646 ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue, 15 Feb 2011, Mark Calabretta wrote: The quadratic calamity is one of the few concrete arguments given by the proponents of dropping leap seconds (viz the GPS World article). I had another look at the article, and it doesn't use the quadratic increase DUT1 as an argument against UTC. They discuss it, but they only look ahead about a century, which is far too little for the rate difference to cause serious difficulties. Their arguments are that more frequent leap seconds will increase the amount of irritation they cause (which is the main reason they dislike leap seconds) but on the other hand people might get used to accommodating them; and if the tolerance on DUT1 is increased or leap seconds are abolished entirely then time signals will have to be modified to cope. They conclude that the best options are probably an increased bound on DUT1 and/or periodic leap seconds. (for reference: http://gauss.gge.unb.ca/papers.pdf/gpsworld.november99.pdf) I have been saying that, as a reason for changing UTC today, it is a specious argument that should be rejected. Yes. It's also a bogus argument for keeping leap seconds. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue, 15 Feb 2011, Paul Sheer wrote: Have you looked at the Olson source? Yes. In any case, whatever solution ye'all come up with should not merely be In Principle. It should come as a patch on some real code. No patches are needed. If leap seconds are abolished then POSIX's model of time becomes correct. Olson's tzcode (in the standard configuration) works on top of POSIX time so it ignores leap seconds. It will continue to work exactly as it does now. The process for updating the tzdata files will remain exactly as it currently is. I think what you will find is that there is no technical difference between moving leap seconds into TZ, and eliminating leap seconds and adjusting TZ. There is already code to handle leap seconds like timezones, but it is incompatible with POSIX and large amounts of other code and with NTP and other time broadcast systems. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Tony Finch d...@dotat.at : [...] There is already code to handle leap seconds like timezones, but it is incompatible with POSIX and large amounts of other code and with NTP and other time broadcast systems. Of course you are exactly right. Now, consider an application that wants to support BOTH posix time and Olson's other time scale. This is NOT currently supported. An application author has to choose one or the other. SO THERE IS NO MIGRATION PATH. the only compatibility functions are posix2time and time2posix which are woefully inadequate. To get this to work you need API changes to report both time scales. Even if you invent a new timescale, you need a migration path. This means possibly extending NTP and Olson's library because it only allows one timescale and this is pre-determined by environment variables. -paul ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Mon, 14 Feb 2011, Mark Calabretta wrote: On Fri 2011/02/11 15:42:41 -, Tony Finch wrote See for example http://six.pairlist.net/pipermail/leapsecs/2011-January/002124.html where Rob Seaman wrote Civil timekeeping is cumulative. Tiny mistakes posing the problem will result in large and growing permanent errors. You'd have to be a lawyer to be able to interpret that as an argument for the quadratic catastrophe supporting UTC. Yes, it isn't a very good quote, just the first one I found with a bit of searching. Rob frequently argues that we can't use a pure atomic timescale as the basis of civil time because of the quadratically increasing offset between UT1 and TAI. You yourself made the same argument in your previous message. The counter-argument is mainly to point out that the offset is negligible from the point of view of the majority of people. It won't become uncomfortable until about a thousand years in the future, by which time leap seconds will be stretched to breaking point. Furthermore using timezones to keep civil time in sync with the sun leads to simpler software and it will work for over ten thousand years. So it is not correct to argue that because abolishing leap seconds will lead to a quadratic catastrophe therefore we must keep leap seconds. It's wrong mainly because the catastrophe isn't actually a catastrophe. There is a problem for people who need UT1, because they will need to upgrade their systems that deal with it. But the magnitude and accelerating increase of DUT1 are quite managable. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Tony Finch wrote: Rob frequently argues that we can't use a pure atomic timescale as the basis of civil time because of the quadratically increasing offset betwee UT1 and TAI. Well no, I don't think I've ever made such an argument. It is a question of rates, not offsets. And the two clocks would continue to be mismatched in rate even if the Earth's length-of-day remained fixed from here on out. The counter-argument is mainly to point out that the offset is negligible from the point of view of the majority of people. The differing rates are not negligible and the resulting offsets (clock setting errors) will continue to accumulate whether or not a quadratic apocalypse is looming. It is simply true that TAI counts out SI-seconds, but UTC tracks synodic days. They are two different clocks. It is this silly insistence on treating them as the same thing that is generating all the trouble. The counter-argument asserts that synodic days are negligible. Many here disagree with this naive and self-serving assertion. It won't become uncomfortable until about a thousand years in the future, Rather, it will immediately break large quantities of expensive astronomical systems and software. Not your problem? It is mine. by which time leap seconds will be stretched to breaking point. Here is where you are reinserting an assertion about the quadratic end-of-days. Leap seconds are at least as adaptable as anything else suggested here. But again - the ITU draft recommends *nothing*. It makes no assertions of its own about what mechanism will eventually bleed off the leap-second-equivalents. The ITU simply wants to dump the problem on later generations (and current astronomers). For more than 10 years we have had no option but to continue to try to stop the ITU from making a colossally stupid decision. There is no deadline. Table the attempt to redefine UTC. If you need to revise TAI or define a new leap-less timescale, just go ahead and do it. Meanwhile we can start discussing the proper engineering of the next-generation timekeeping standards in coordination with all the stakeholders, not just this tiny in-group. Furthermore using timezones to keep civil time in sync with the sun leads to simpler software and it will work for over ten thousand years. No. Breaking timezones on top of breaking UTC with the apparent motivation of allowing TAI to be suppressed is bad on top of bad on top of bad. Understand the problem, engineer a solution, skip the politics and drama. We should take our time and get it right. Rob Seaman National Optical Astronomy Observatory ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Tony Finch wrote: Furthermore using timezones to keep civil time in sync with the sun leads to simpler software and it will work for over ten thousand years. No. Breaking timezones on top of breaking UTC with the apparent motivation of allowing TAI to be suppressed is bad on top of bad on top of bad. You two, Have you looked at the Olson source? If anyone is to judge how simple it is to fiddle with timezones, they should first be thoroughly familiar with this C code. In any case, whatever solution ye'all come up with should not merely be In Principle. It should come as a patch on some real code. There is only one way to settle this debate: CODE OFF!!! I think what you will find is that there is no technical difference between moving leap seconds into TZ, and eliminating leap seconds and adjusting TZ. Perhaps it's just a matter of granularity. *shrug* The power of the Jedi-coder flows from the SOURCE. -paul ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue 2011-02-15T02:07:59 +0200, Paul Sheer hath writ: In any case, whatever solution ye'all come up with should not merely be In Principle. It should come as a patch on some real code. Which part of this is not already implemented by the code when it uses the right zoneinfo files? To be sure, using the right files has to come with a loud DANGER WILL ROBINSON! disclaimer that says You are violating POSIX. You have to use something like a Meinberg NTP server set to provide TAI. You have to make sure you never exchange historic file timestamps with systems that have complied with POSIX. Other than that it looks like people are doing this, they just seem not to like to talk about it, perhaps because POSIX-non-compliance violates FIPS. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick ObservatoryNatural Sciences II, Room 165Lat +36.99855 University of CaliforniaVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Mon 2011/02/14 18:00:02 -, Tony Finch wrote in a message to: Leap Second Discussion List leapsecs@leapsecond.com Rob frequently argues that we can't use a pure atomic timescale as the basis of civil time because of the quadratically increasing offset between UT1 and TAI. You yourself made the same argument in your previous message. Howzat! The quadratic calamity is one of the few concrete arguments given by the proponents of dropping leap seconds (viz the GPS World article). It continues to surface over a decade later. I have been saying that, as a reason for changing UTC today, it is a specious argument that should be rejected. The solution, in the distant future when it does start to bite, will be to measure the length of day properly - finally admit that there are more than 86400 SI seconds in it. Regards, Mark Calabretta ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Mon, 2011-02-14 at 16:23 -0800, Steve Allen wrote: Which part of this is not already implemented by the code when it uses the right zoneinfo files? 1. let say we want a future where timezones are adjusted by 30 minutes whenever the sun starts rising too late. Write this into the Olson library as a managable feature. Think up an infrastructure. Let's see how it would play out. If you can find a way to make it work we can get rid of leap seconds. If you can't then so much the better. Heck, it's a better discussion to have than Is too! Is not! Is too! Is not! Is too! 2. the ability to compute leap-sec-inclusive and leap-sec-excluded in the same thread without changing the environment variables. This would allow one to store both timestamps. Quite useful actually if we are going to keep leap seconds AND have real utc AND interoperate with posix systems. One could use this for absolute SI time diffs, as well as future time-stamps (like calandar appointments) where you don't know in advance how many leapsecs are coming. You would need NTP + OS to track both posix time and TAI. No one has implemented this. It's like we are planning IPv6 migration with no dual stack. -paul ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
What's the point? Two links to refresh the discussion: http://www.springerlink.com/content/g216411573882755/ http://maia.usno.navy.mil/eopcppp/eopcppp.html Paul Sheer wrote: I think what you will find is that there is no technical difference between moving leap seconds into TZ, and eliminating leap seconds and adjusting TZ. Vast difference. Steve Allen's zoneinfo idea preserves universal time separate from the new (or refurbished) atomic timescale. On the other hand, the whole point of rubber timezones is to eradicate universal time. I know everybody here revels in these technical bake-offs, but it risks losing the underlying issues in the underbrush. Issue number one: atomic time and mean solar time are two different things because SI-seconds and synodic days are inherently distinct measures of our days. Two suggestions for real progress on these two inherently different timescales: 1) Honor the Torino consensus and call any new leap-less atomic timescale something other than UTC. 2) Improve the UTC we have. The state of the art in predicting UT1 (and thus scheduling UTC) is described in: http://www.springerlink.com/content/g216411573882755/ The state of the art appears to be significantly better than a tenth second over 500 days. There is an ongoing successor project: http://maia.usno.navy.mil/eopcppp/eopcppp.html Combining these improved predictions with prudently relaxed DUT1 constraints should permit extending leap second scheduling to several years. These steps can be taken today with no tedious international negotiations. With the ITU's sword of Damocles removed we (meaning the real community of timekeeping stakeholders that is much broader than the group here) can consider how best to implement our next generation timekeeping system(s), rather than how worst we can screw up the functional timekeeping we inherited from our betters. *That's* the point! Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Mark Calabretta said: The speculation on the list is that in the absence of a central authority, local governments will act as their people request when it is staying dark too late and parents can't get their kids to bed with the sun still shining, or have to drive to work in the dark too many days of the year. Yes, it seems a likely response. The underlying assumption is that people expect the Sun to be roughly overhead at noon to within a tolerance of about an hour. I don't believe that's so. I might agree that people expect it to be within about 3 hours, but that's all. Leaping timezones would be tenable if they all leapt at the same time. However, I think we agree that that won't happen. What's the problem with them moving on different dates? Um, beyond the problems we already have because they move on loads of different dates. Currently the main chaotic element of timezones is concerned with the start and end date of DST. The chaos is restricted to two periods, sometime in autumn and spring, and it only amounts to one hour to and fro. FX: laughter. As an example, last year Egypt had two separate sessions of DST. Leaping timezones, each at their own pace, can only add an extra level of chaos, one that will eventually lead to multi-hour offsets that continue to grow over time. Why? Adjacent countries might move from a delta of an hour to zero and then back again, but why would one place move at a different *rate* (i.e. leaps per millenium) to another? In other words, how is this any more complex than Russia deciding not to end DST this year? -- Clive D.W. Feather | If you lie to the compiler, Email: cl...@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646 ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Fri, 11 Feb 2011, Mark Calabretta wrote: On Thu 2011/02/10 10:43:40 -, Tony Finch wrote Also, the quadratic catastrophe argument is usually used in support of UTC. Really? Can you provide references for that. See for example http://six.pairlist.net/pipermail/leapsecs/2011-January/002124.html where Rob Seaman wrote Civil timekeeping is cumulative. Tiny mistakes posing the problem will result in large and growing permanent errors. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Ian Batten said: And people routinely live in places where solar time is several hours adrift from civil time --- Brest, France for example is four degrees west of Greenwich, yet in the summer is on UTC+2 --- so at noon civil time it is 0945 solar time. Parts of (mainland) Spain are even further west than that, and there are parts of Alaska where it's 0842 solar time at civil noon. -- Clive D.W. Feather | If you lie to the compiler, Email: cl...@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646 ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Feb 11, 2011, at 8:42 AM, Tony Finch wrote: See for example http://six.pairlist.net/pipermail/leapsecs/2011-January/002124.html where Rob Seaman wrote Civil timekeeping is cumulative. Tiny mistakes posing the problem will result in large and growing permanent errors. Great to see folks are reading my messages :-) That message was about time-like variables. The quadratic thread is about their second derivatives. Differential equations make the world go round. Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Thu, 10 Feb 2011, Mark Calabretta wrote: Leaping timezones would be tenable if they all leapt at the same time. However, I think we agree that that won't happen. They leap about all the time at arbitrary times, so I wonder why you think that isn't tenable. Currently the main chaotic element of timezones is concerned with the start and end date of DST. The chaos is restricted to two periods, sometime in autumn and spring, and it only amounts to one hour to and fro. No, the main chaotic element is that the rules keep changing. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Thu, 10 Feb 2011, Mark Calabretta wrote: If we're seriously expected to accept the quadratic catastrophy argument for immediately changing UTC Also, the quadratic catastrophe argument is usually used in support of UTC. It is argued that a very small and slowly increasing rate difference between civil time and earth rotation is a disaster and unacceptable because the rate difference becomes quadratically larger. Never mind that it won't make any practical difference for thousands of years and that we already have an older mechanism that works better than leap seconds for dealing with differences between an international time scale and local civil time. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 10 Feb 11, at 0122, Mark Calabretta wrote: On Wed 2011/02/09 11:44:14 PDT, Warner Losh wrote in a message to: leapsecs@leapsecond.com The speculation on the list is that in the absence of a central authority, local governments will act as their people request when it is staying dark too late and parents can't get their kids to bed with the sun still shining, or have to drive to work in the dark too many days of the year. Yes, it seems a likely response. The underlying assumption is that people expect the Sun to be roughly overhead at noon to within a tolerance of about an hour. I don't think that's quite true. For a start off, in large parts of the world overhead simply means at its zenith which might be quite low in the sky, and to determine where it's solar 1100, 1200 or 1300 would require careful observation. So peoples' sensitivity is probably a lot coarser than you imply. And people routinely live in places where solar time is several hours adrift from civil time --- Brest, France for example is four degrees west of Greenwich, yet in the summer is on UTC+2 --- so at noon civil time it is 0945 solar time. The pressure to move the UK onto European (ie UTC+1/UTC+2 daylight saving) mostly comes from the south of England, which would leave Cornwall in a similar position to Brest: there's a lot of enthusiasm for it, as long, light evenings are great for the tourist industry. I suspect people in 2011 are more tolerant of that scenario than they would be of the opposite, where at 1200 solar it's 0945 civil, leading to very dark evenings. So I think the limits for social acceptability on civil/solar offsets are asymmetric, with three hours on way probably acceptable in some situations, while one hour the other may cause some dissent. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
It's been a while... Can you remind me why we will need to continue to pretend that there are 86400 SI seconds in a day, past the time when there are actually 86401 (or more)? Why is because there is a semi-infinite number of existing lines of code, right now in use, that calculate the day from the second and visa-versa using, d = t / 86400 t = d * 86400 they do this for reasons of a) expediency b) interoperability, and c) conformance to POSIX v3. -paul ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Feb 10, 2011, at 5:39 PM, Warner Losh wrote: Without a plan, people will keep doing what they are doing now. Today's code might not be around in 10k years, but if people don't come up with a plan, then code written 1k or 5k years from now will still have the same problems. I think the question is whether code will be written and whether people will do the writing line-by-line, method-by-method, class-by-class. Multi-radix representations will live forever, however, if only to parse old timestamps :-) Maybe they'll be working on an ISO-8601 v2.0 by that point... ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message 20110209025648.gb5...@ucolick.org, Steve Allen writes: Further evidence of this is that UN registers all internation treaties its member states have entered into, in accordance with the UN charters article 102, and you can see all of these treaties at http://treaties.un.org In there I do not find the ITU-R's Radio Regulations, so perhaps the whole point of this mail list is moot, for we are not bound to follow them? Uhm, you have not actually read the text of the proposal ? All ITU-r *Recommendations* follow this form: The ITU Radiocommunication assembly, considering bla. bla. bla. recommends bla. bla. bla. The only difference being that a few luck of them, have the work unanimously inserted before recommends after the vote. In there I also do not find Meter Convention, so perhaps the UN list is not comprehensive. The Meter Convention does say this http://www1.bipm.org/jsp/en/ViewCGPMResolution.jsp?CGPM=15RES=5 Notice again the language: judges that this usage can be strongly endorsed Other hint: The Meter Convention has not been able to metrify USA yet. QED: Governments are free to fuck up their timekeeping as they see fit. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message 0ea57b08-af7c-4bbe-8a56-b1376e873...@batten.eu.org, Ian Batten wri tes: Sovereign states have some degree of control over civil time; [...] Although it's not obvious to me that in the UK, at least, they have any practical authority over time. The Weights and Measures Act 1985 S.6(1)(c) makes it clear that they could check clocks [...] The point here is not if the exercise any authority, but if they (could) have it in the first place. Nothing prevents the parliament from passing a law that says all clocks must run backwards if they wanted to. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue, 8 Feb 2011, Warner Losh wrote: On 02/08/2011 14:39, Rob Seaman wrote: C) As pointed out on numerous occasions in the past, these kaleidoscopic timezones would accelerate quadratically just like leap seconds. This problem isn't solved by this method either. True. Except that timezone adjustments continue to work much further into the future than leap seconds. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue, 8 Feb 2011, Rob Seaman wrote: B) Detailed expert knowledge would become necessary to answer even simple questions of comparing both clock intervals and Earth orientation questions either in a single place or across epochs and locations. We have that today. We have a soupçon of the zest of complex design. The kaleidoscopic timezone notion is the Deepwater Horizon of meddling with timezones. If you think the current TZ system is that simple you must be living in a fantasy world. But you guys continue to reject Steve Allen's zoneinfo option...which represents a system layered on a relatively static timezone DB. Relatively static? Fairy tales! Punting to local governments is vastly more complex. We already deal with that complexity. The existing TZ software already has some odd example timezones that describe things like local apparent solar time at a particular location. It would be a pretty good way to distribute DUT1 tables so you could translate between local time - atomic time - universal time to one second precision. (This is true for at least the Olson code; there is probably other software that makes too many assumptions for this to work.) Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD.___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message ae1ee06f-17e5-46e2-abc2-c0700cb1a...@noao.edu, Rob Seaman writes: Clive D.W. Feather wrote: I reserve the right to disagree. The point is that dumb is what the rubber timezone folks say - and rubber timezones are an order of magnitude more dumb than either rubber seconds or zoneinfo-for-leapseconds. Says who ? Rubber seconds made even interval measurement a tricky proposition, globally. Leaving civil time in the hands of governments is not only non-optional, it also limits any damage that can be done geographically. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Tony Finch wrote: Warner Losh wrote: Rob Seaman wrote: C) As pointed out on numerous occasions in the past, these kaleidoscopic timezones would accelerate quadratically just like leap seconds. This problem isn't solved by this method either. True. Except that timezone adjustments continue to work much further into the future than leap seconds. No - the 2nd derivative is the same whether the leap-second-equivalents (LSEs) are batched one-by-one or 3600 at a time. (Putting aside the question of whether timezone adjustments would meet the project requirements in the first place.) The current leap second policies are constrained to twice per year - this would correspond to a timezone do-se-do of 1800 years. The actual standard, though, is 12 per year - that brings it down to 300 years, which seems similar in level of intrusiveness. Larger interruptions must occur less frequently to be tolerated. However, a leap second per day (or even multiples) is not logistically out of the question. This is Mark Calabretta's epsilon. One-per-day would mean a timezone reorganization every ten years, which would be absurdly unacceptable compared to taking our daily epsilon vitamin. Leap seconds would be much more robustly tolerated into the far distant future than rubber timezones. ...which is all just to say that in sampling theory a finer grid is generally preferred. For instance, the usual sqrt(1/12) quantization error applies as the LSE binning grows. The usual disclaimer: none of this is in the actual ITU draft. There are complications with any position. There should be a coherent plan developed in advance of any change to the UTC standard. Due diligence has not been served. Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 02/09/2011 09:05, Rob Seaman wrote: Tony Finch wrote: Warner Losh wrote: Rob Seaman wrote: C) As pointed out on numerous occasions in the past, these kaleidoscopic timezones would accelerate quadratically just like leap seconds. This problem isn't solved by this method either. True. Except that timezone adjustments continue to work much further into the future than leap seconds. No - the 2nd derivative is the same whether the leap-second-equivalents (LSEs) are batched one-by-one or 3600 at a time. (Putting aside the question of whether timezone adjustments would meet the project requirements in the first place.) It is a lot easier to adjust by an hour for local time than it is to have a leap second every month, or more often. Thus Tony is right: the zoneinfo files adjusting local time via timezone shifts mandated by local government would easily outlast leap seconds. To be clear also: the idea isn't to adjust the TI time to local sun time frequently, but only when it drifts by an hour or so. That's why I keep saying that timezone changes would be on the order of a few dozen every few hundred years. This is in the noise compared to the recent timezone changes which happen on the order of dozens per year. The current leap second policies are constrained to twice per year - this would correspond to a timezone do-se-do of 1800 years. The actual standard, though, is 12 per year - that brings it down to 300 years, which seems similar in level of intrusiveness. Larger interruptions must occur less frequently to be tolerated. I'm not sure I follow this point... However, a leap second per day (or even multiples) is not logistically out of the question. This is Mark Calabretta's epsilon. One-per-day would mean a timezone reorganization every ten years, which would be absurdly unacceptable compared to taking our daily epsilon vitamin. The US changes its timezone rules on average every 10 years (DST has been uniform for 45 years or so and has changed 5 times). Tweaks to the US timezone rules happen annually for different parts of the country (this country moves from this timezone to that, etc). Leap seconds would be much more robustly tolerated into the far distant future than rubber timezones. what are rubber timezones that you talk about? I don't think we're talking about the same thing. The idea that's been put forth is that the transition would be made all at once. Eastern Time zone would go from TI-5 to TI-4, most likely by failing to fallback one year in the fall. Warner ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Wed, 9 Feb 2011, Rob Seaman wrote: PHK's position is that hundreds of local governments (that he appears to consider beneath contempt) would have to act separately or severally during each adjustment. Right. Just as they do at present for political reasons. Even if one-a-day is introduced this would be the case. Er what?! Days won't become 25 hours long until well over a hundred million years in the future! The current specification for UTC fails when we require more than 12 leap seconds per year, which is some time between the years 3000 and 4000. Very few timezone adjustments are needed to maintain synchronization with that small discrepancy. Even in the year 10,000 there will still be several decades between adjustments. A leap-hour-by-whatever-name cannot be ignored even by a microwave oven and no central authority would exist. Right, just as is the case for timezone changes now. The lack of central authority makes the system very flexible and resilient. Timezone pressure would have to be released when 3600 leap seconds accumulate. Consider earthquakes. The longer the period of quiescence, the larger the quake when it happens. There is no quiescence because the politicians keep changing them. Since it is a tenet of the rubber timezone notion that there would be no central authority, each timezone quake would have technical, historical, legal and economic aftershocks lasting possibly decades as one locality after another shifted. For example look at the catastrophic problems caused by the 2007 timezone changes in North America - worse than Y2K! Governments fell! Lawsuits continue to this day! Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Wed, 2011-02-09 at 09:49 -0700, Warner Losh wrote: It is a lot easier to adjust by an hour for local time than it is to have a leap second every month, or more often. Thus Tony is right: the zoneinfo files adjusting local time via timezone shifts mandated by local government would easily outlast leap seconds. This is a crudely thought-out plan. One cannot possibly know what will be easier 100's of years from now. One can desist leap seconds at any time however. Therefore logically, it is better to do nothing. -paul ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 9 Feb 2011, at 18:44, Warner Losh wrote: On 02/09/2011 10:48, Rob Seaman wrote: The idea that's been put forth is that the transition would be made all at once. Eastern Time zone would go from TI-5 to TI-4, most likely by failing to fallback one year in the fall. Exercise for the class: Which is it? Will the governments act separately or together? How will governments north and south of the equator coordinate given that daylight saving time occurs in the local summertime during opposing seasons? Etc and so forth. Ummm, no coordination is necessary, although some will likely naturally occur. Eastern Time is purely a US construct that Canada also uses. Since the central governments of US and Canada set the time for the whole country, I'd imagine that they'd coordinate like they did with the last round of date changes for DST. Or not, if they aren't so friendly in a few hundred years. Precisely. The daylight savings rules were subtly different between the UK and France for many years (fourth Sunday vs last Sunday), but nothing untoward happened. The rules are markedly different between Europe and the US (US starts a few weeks earlier and ends a week later) and again, the consequences are trivial. As a consequence of failing to incorporate leap seconds would be to make civil time slowly advance relative to solar time (ie, become progressively more daylight-savings-y), and in general there is a trend towards civil time that trades lighter evenings for darker mornings, many countries might be happy just to drift anyway. I mean, simply failing to adopt leap seconds would solve the problem of getting the UK onto CET in about 5000 years, without having to get Bill Cash harrumping about Brussels Times or anything... ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message 6d097a07-04ec-4ace-ad99-4c647ab22...@noao.edu, Rob Seaman writes: In context my statement was: By comparison, a leap second is introduced by a central authority [...] What authority would that be, and what powers would it have ? Remember: it's called a recommendation for a good reason. I don't need to remind you, that nobody would be surprised if the vote fails in ITU-R and USA then throw the toys out of the pram and declares that they will discontinue leap-seconds anyway. Heck, we had casually mentioned to Fox News, at the right time in the patriotic fever after 2001, that leap-seconds were french they would have been gone for 9 years now already, unless somebody at NIST were quick enough to rename them freedom seconds Yeah, it wouldn't be pretty, but neither are engineering drawings in two units of measurements. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Poul-Henning Kamp wrote: What authority would that be, and what powers would it have ? Per SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE, we know that: NO positive leap second will be introduced at the end of June 2011. I don't need to remind you, that nobody would be surprised if the vote fails in ITU-R I'd be surprised. They haven't shown much sense yet. and USA then throw the toys out of the pram and declares that they will discontinue leap-seconds anyway. ...but I'd be gobsmacked if the USA (whatever that means) acted unilaterally in that eventuality. There literally is no hurry. This is a completely manufactured crisis. Factions in the USA disagree about the issues. Yeah, it wouldn't be pretty, but neither are engineering drawings in two units of measurements. Pretty isn't the primary goal of engineering. Optimal isn't even the goal. Engineering is an exercise in satisficing to meet requirements. Seeking consensus in advance of decision-making is the most efficient way to go about it. Expending a little effort to actually discover the requirements is even more fundamental. Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message e97e8012-cc6f-4948-b291-a82868873...@noao.edu, Rob Seaman writes: Poul-Henning Kamp wrote: What authority would that be, and what powers would it have ? Per SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE, we know that: NO positive leap second will be introduced at the end of June 2011. Please try to answer my question, rather than cite a document which at best has the legal force of friendly advice. What would happen to a country, for examples sake, lets assume USA, if it decided not follow Daniels recommendation ? I'm sure the director of BIPM would *love* to try it out with respect to the inches/meter detail... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Wed 2011/02/09 10:59:39 -, Tony Finch wrote in a message to: Leap Second Discussion List leapsecs@leapsecond.com Except that timezone adjustments continue to work much further into the future than leap seconds. If we're seriously expected to accept the quadratic catastrophy argument for immediately changing UTC, would it be too much to expect that its replacement actually solve the problem rather than simply delay it? Regards, Mark Calabretta ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Wed 2011/02/09 11:44:14 PDT, Warner Losh wrote in a message to: leapsecs@leapsecond.com The speculation on the list is that in the absence of a central authority, local governments will act as their people request when it is staying dark too late and parents can't get their kids to bed with the sun still shining, or have to drive to work in the dark too many days of the year. Yes, it seems a likely response. The underlying assumption is that people expect the Sun to be roughly overhead at noon to within a tolerance of about an hour. There's a natural force here that pushes the governments, each at their own pace, to implement the change. Given this natural push, and the complete chaos of timezones today, it is natural to think this is a good solution to the problem. Leaping timezones would be tenable if they all leapt at the same time. However, I think we agree that that won't happen. Currently the main chaotic element of timezones is concerned with the start and end date of DST. The chaos is restricted to two periods, sometime in autumn and spring, and it only amounts to one hour to and fro. Leaping timezones, each at their own pace, can only add an extra level of chaos, one that will eventually lead to multi-hour offsets that continue to grow over time. Regards, Mark Calabretta ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message c222a54a-321e-4a5f-ad7a-efb12a4fd...@noao.edu, Rob Seaman writes: Phrases like tight coupling are misleading. The ITU position has only ever been to remove *all* coupling. On this list we have often discussed various ways to relax the current constraints. It is the ITU who have been inflexible. You are fudging things as usual. The ITU proposal does not in fact talk about civil time at all, it talks only about the timescale civil time is defined relative to: UTC. The relationship between civil time and earth rotation is already a decision for respective governments, who get to decide the offset between civil time and UTC for their country. History has shown that very few, if any, governments have been unable to carry through their more or less well thought out policies in this area. Should your local government decide to keep the difference between Earth Rotation and civil time less than some tolerance, they are free to do so, by adjusting the civil time-UTC offset as they please. As evidence of this, please note that there are plenty of timezones not using multiple of 3600 seconds offsets. The ITU proposal therefore neither loosens nor removes the coupling between civil time and earth rotation. The ITU proposal transfers that decision to the countries governments, where it belongs. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue, 8 Feb 2011, Rob Seaman wrote: I'd say that history is pretty quiet on timekeeping issues in general. I think very highly of Dava Sobel's Longitude, but one book does not a library make. There's also Saving the Daylight by David Prerau. (The title has varied a bit.) Also Calendrical Calculations by Reingold and Dershowitzis tangentially relevant since it includes models for observational calendars. Any other recommendations? Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
I said: Civil timekeeping is a worldwide system. Poul-Henning Kamp wrote: No it is not. It is remarkable how the most aggressive responses to my posts are when I mention system engineering or best practices or otherwise suggest that this is fundamentally an exercise in proper system design. Nobody can prevent your government or my government from defining local time as UTC + Xh 31 minutes + 41.5 seconds. Sounds like a good argument for a coherent international process, not for tossing the UTC baby to the dingos. UTC is not civil time anywhere, I understand that you wish to assert that local time == civil time. But you also assert that computer networks worldwide must be synchronized. Is this latter somehow not a civil function? Local time is layered on UTC The former deals with local foibles. The latter with global standards. One of those standards is the synodic day. UTC is layered on TAI, which introduces a separate global standard, the SI-second. The three layers work together. If we're to entertain remodeling the underlying architecture on a fundamental scale then system engineering best practices are the tools to do this. Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Sovereign states have some degree of control over civil time; the remaining control is in the control of individuals, either through personal whims or voluntary collective action. The IAU, ITU, BIPM, ISO, and all the rest do not have control over civil timekeeping because the weights and measures inspectors who enforce measurement laws do not take orders from them, they take orders from the sovereign state that employs them. Gerry Ashton On 2/8/2011 11:50 AM, Rob Seaman wrote: I said: Civil timekeeping is a worldwide system. Poul-Henning Kamp wrote: No it is not. It is remarkable how the most aggressive responses to my posts are when I mention system engineering or best practices or otherwise suggest that this is fundamentally an exercise in proper system design. Nobody can prevent your government or my government from defining local time as UTC + Xh 31 minutes + 41.5 seconds. Sounds like a good argument for a coherent international process, not for tossing the UTC baby to the dingos. UTC is not civil time anywhere, I understand that you wish to assert that local time == civil time. But you also assert that computer networks worldwide must be synchronized. Is this latter somehow not a civil function? Local time is layered on UTC The former deals with local foibles. The latter with global standards. One of those standards is the synodic day. UTC is layered on TAI, which introduces a separate global standard, the SI-second. The three layers work together. If we're to entertain remodeling the underlying architecture on a fundamental scale then system engineering best practices are the tools to do this. Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue, 8 Feb 2011, Rob Seaman wrote: UTC is not civil time anywhere, I understand that you wish to assert that local time == civil time. But you also assert that computer networks worldwide must be synchronized. Is this latter somehow not a civil function? Civil usually relates to a particular country. My civil time is not the same as your civil time, neither is my civil service nor my civil war. I would say that worldwide co-ordination is better described as international rather than civil. On the other hand, the OED says the civil in civil time is to distinguish it from astronomical time, so the civil year has a whole number of days unlike an astronomical day, and a civil day is not defined by local apparent or mean solar time. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7, DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR ROUGH. RAIN THEN FAIR. GOOD. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 02/08/2011 07:55, Rob Seaman wrote: Regarding your current question, I would personally assert: Coupling civil timekeeping to Earth rotation is a necessary feature. I suspect some others here might not be willing (yet) to promote this to consensus :-) Phrases like tight coupling are misleading. The ITU position has only ever been to remove *all* coupling. On this list we have often discussed various ways to relax the current constraints. It is the ITU who have been inflexible. The current ITU proposal would have the effect of moving the coupling of the Earth's rotation from the time that is broadcast (now called UTC) to the timezones that local governments promulgate. While not explicitly stated in the proposal something like this would naturally happen every few hundred years. I'd be willing to agree that Coupling of Civil time to the earth is required. Coupling of the successor to UTC isn't required, or at least there's not consensus that it is required. Warner ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue 2011-02-08T13:14:27 -0700, Warner Losh hath writ: I'd be willing to agree that Coupling of Civil time to the earth is required. Coupling of the successor to UTC isn't required, or at least there's not consensus that it is required. The broadcast time signals should be as uniform as is technologically possible according to best current practices. Most governments of the world are signatories to agreements which state that Universal Time is a subdivision of the mean solar day which ultimately produces the calendar. Unless those agreements are explicitly terminated the notion of time continues to deserve input from astronomical measurements. We have the technical means to do both. The question is about the will. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick ObservatoryNatural Sciences II, Room 165Lat +36.99855 University of CaliforniaVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 02/08/2011 13:29, Steve Allen wrote: On Tue 2011-02-08T13:14:27 -0700, Warner Losh hath writ: I'd be willing to agree that Coupling of Civil time to the earth is required. Coupling of the successor to UTC isn't required, or at least there's not consensus that it is required. The broadcast time signals should be as uniform as is technologically possible according to best current practices. Most governments of the world are signatories to agreements which state that Universal Time is a subdivision of the mean solar day which ultimately produces the calendar. Unless those agreements are explicitly terminated the notion of time continues to deserve input from astronomical measurements Treaty obligation isn't something that's come up here before. Do you have references to which treaties apply? Warner ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Warner Losh wrote: The current ITU proposal would have the effect of moving the coupling of the Earth's rotation from the time that is broadcast (now called UTC) to the timezones that local governments promulgate. This would be chaos for anyone needing to compare timestamps in different locales and eras. If a simple table of second-scale adjustments is deemed unacceptable, how about squabbling over timezone policies for many thousands of nations, provinces, states and cities? The point is that the common UTC makes these negligible now, but wouldn't later because it is being demoted to take the place of TAI. While not explicitly stated in the proposal something like this would naturally happen every few hundred years. There is nothing natural about it and whatever plan is developed the ITU should explicitly include massive issues like this in the process. The ITU has no plan. The ITU has performed nothing that even vaguely resembles due diligence. I'd be willing to agree that Coupling of Civil time to the earth is required. Great! Consensus! Coupling of the successor to UTC isn't required, or at least there's not consensus that it is required. As there is no consensus that it isn't required... Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Poul-Henning Kamp wrote: Sometimes it is civil, sometimes it is military, most of the time it is corporate. We have frequently debated vocabulary here. This is why I suggested a glossary would be a good idea. Civil timekeeping has often been taken to mean something like the common worldwide timescale underlying the timezones and serving manifold purposes for everybody excepts specialists (and often for them as well). I reject the attempt to equate civil timekeeping with the big mess of timezones administered by random governments worldwide including foibles like daylight saving. In particular, the only reason DST works is that we have standard time to fall back on, and the only reason the standard timezones work is that they have UTC to fall back on. And finally: The reason I react to your mantra about best systems engineering practises is that the time window for that is long past, Rather, the window was never opened. The ITU has done nothing except pursue this one insipid initiative since day one and has trampled every effort at consensus. They ignored the results of the meeting at Torino in 2003 and they have refused to participate in this list. System engineering is like quitting smoking. It's better if you start earlier, but starting late is better than never starting. Arguing that an inherently technical issue is best addressed by crappy engineering is - well - dumb. Not to mention that the current standard is viable for centuries yet and any haste was artificially injected by the ITU themselves in the first place. Politics is the continuation of systems engineering with different means. Hence: http://www.archive.org/details/SF121 Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 2011-02-08 16:29, Poul-Henning Kamp wrote, answering Rob Seaman: Civil timekeeping is a worldwide system. No it is not. UTC is a worldwide coorporation or worldwide coordination if you will. There is no international entity which can mandate what civil time must be in any particular country, and therefore there is no other system than what emerges through voluntary coordination and cooperation. And the cooperation only happens to the extent people want to, there are no penalties for deciding on stupid timekeeping in your own country. Nobody can prevent your government or my government from defining local time as UTC + Xh 31 minutes + 41.5 seconds. In 1884, an international conference decided: That the Conference proposes the adoption of a universal day for all purposes for which it may be found convenient, and which shall not interfere with the use of local or standard time where desirable. That this universal day is to be a mean solar day; is to begin for all the world at the moment of mean midnight of the initial meridian, coinciding with the beginning of the civil day and date of that meridian; and is to be counted from zero up to twenty-four hours. That international agreement has since become, and still is, the rationale for the worldwide use of UT, UT2, and UTC as the basis for the definition of all local civil time scales, even at those strange places where the civil time scale is defined as UTC + 31 min + 41.5 s. The proposed distribution of a translate of TAI as the time scale to be distributed worldwide, and thus to be taken as the basis of all civil time scales, amounts to the abrogation of this decision of 1884. So many esoteric technical issues have been raised in the discussion about this matter that I am wondering whether the ITU-R people may still be aware of the importance of their decision: they are going to revise the agreement of 1884. Michael Deckers. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
In message 20110208202941.gg1...@ucolick.org, Steve Allen writes: Most governments of the world are signatories to agreements which state that Universal Time is a subdivision of the mean solar day which ultimately produces the calendar. What argrements are you thinking of ? And is the averaging period defined in them ? Otherwise simply picking a suitable averaging period, 1800-2100 for instance, will fix that. the notion of time continues to deserve input from astronomical measurements. I don't think notion of time deserves anything of the sort, time seems to have managed just fine before the invention of astronomers :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Warner Losh wrote: How would it be any different than today? Every few hundred years, the government moves the time zone. Heck, they do that now every few years anyway. Each government would be able to move it as they saw fit, or follow other government's leads. If the US move and Canada doesn't, then what's the harm? A) It would be taking what is currently a doubly indirect pointer and removing the layer in the middle. Dereferencing (converting to UTC) would no longer return a timescale stationary with respect to the synodic day. A robust system with innumerable connections across interfaces and stakeholders worldwide would be made brittle. B) Detailed expert knowledge would become necessary to answer even simple questions of comparing both clock intervals and Earth orientation questions either in a single place or across epochs and locations. What year did Queensland shift from NEW-UTC+10h to NEW-UTC+10h30m? No, no! The second time? C) As pointed out on numerous occasions in the past, these kaleidoscopic timezones would accelerate quadratically just like leap seconds. D) It is asserted that interval timekeeping is hard to do. This would make it orders of magnitude more difficult for many classes of use cases. It ain't all about surfing the current instant into a future so bright we have to wear shades. (And I'm skeptical that sacrificing the UTC baby to the dingo on the beach really improves the surfing anyway.) I don't disagree that there's no plan. Another point of consensus! Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 02/08/2011 14:39, Rob Seaman wrote: Warner Losh wrote: How would it be any different than today? Every few hundred years, the government moves the time zone. Heck, they do that now every few years anyway. Each government would be able to move it as they saw fit, or follow other government's leads. If the US move and Canada doesn't, then what's the harm? A) It would be taking what is currently a doubly indirect pointer and removing the layer in the middle. Dereferencing (converting to UTC) would no longer return a timescale stationary with respect to the synodic day. A robust system with innumerable connections across interfaces and stakeholders worldwide would be made brittle. I don't see why it wouldn't. If you really need synodic day, DUT1 tables would give that. Most people want intervals or do this when the clock on the wall (not the sun) says 3 o'clock. But these problems are well understood in a world where 2am might not exist on the clock on the wall. B) Detailed expert knowledge would become necessary to answer even simple questions of comparing both clock intervals and Earth orientation questions either in a single place or across epochs and locations. What year did Queensland shift from NEW-UTC+10h to NEW-UTC+10h30m? No, no! The second time? We have that today. Tell me, what time is it in Indiana? And how has that changed over the past 20 years? Indiana used to follow DST, then it didn't, then it shifted from one timezone to another. Oh, wait, only some counties did this. Even the olson database won't give you all the answers, but it will give you many of them. C) As pointed out on numerous occasions in the past, these kaleidoscopic timezones would accelerate quadratically just like leap seconds. This problem isn't solved by this method either. True. D) It is asserted that interval timekeeping is hard to do. This would make it orders of magnitude more difficult for many classes of use cases. It ain't all about surfing the current instant into a future so bright we have to wear shades. (And I'm skeptical that sacrificing the UTC baby to the dingo on the beach really improves the surfing anyway.) Given the yearly changes to the timezones today, I'm skeptical about believing that adding a few dozen more every few hundred years would be a huge burden. Warner I don't disagree that there's no plan. Another point of consensus! Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
Warner Losh replies: A) It would be taking what is currently a doubly indirect pointer and removing the layer in the middle. Dereferencing (converting to UTC) would no longer return a timescale stationary with respect to the synodic day. I don't see why it wouldn't. If you really need synodic day, DUT1 tables would give that. Um. You may or may not agree that it is necessary for UTC to remain stationary with the synodic day, but requiring DUT1 tables is certainly an admission that this would indeed no longer be the case. B) Detailed expert knowledge would become necessary to answer even simple questions of comparing both clock intervals and Earth orientation questions either in a single place or across epochs and locations. We have that today. We have a soupçon of the zest of complex design. The kaleidoscopic timezone notion is the Deepwater Horizon of meddling with timezones. Even the olson database won't give you all the answers, but it will give you many of them. But you guys continue to reject Steve Allen's zoneinfo option...which represents a system layered on a relatively static timezone DB. Punting to local governments is vastly more complex. C) As pointed out on numerous occasions in the past, these kaleidoscopic timezones would accelerate quadratically just like leap seconds. This problem isn't solved by this method either. True. More consensus! Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 02/08/2011 16:30, Rob Seaman wrote: Even the olson database won't give you all the answers, but it will give you many of them. But you guys continue to reject Steve Allen's zoneinfo option...which represents a system layered on a relatively static timezone DB. Punting to local governments is vastly more complex. The basic problem with that approach is that you need to update your timezone files for every leap second, and you can never, ever, miss an update, or you are hozed. NTP also does everything in UTC time, so if you come up with one set of data, then get updated timezone info that tells you that you missed a leap second, the underlying clock running in TAI time will suddenly be a second off. This can be mitigated somewhat if you have a working GPS receiver and can afford to wait the 30 minute it may take to get the almanac data to startup, but there are still a large number of situations where you don't know until 'later' that you've made the wrong guess at startup and now everything you've based on a TAI or TAI-like time in your application is off by 1 or more seconds. At least some versions of the timezone code also don't re-read the zonefiles if they change (stating these files every time operation is prohibitively expensive). This means long-running control programs will have systematic errors depending on when they were started relative to the timezone files. And having the program itself restart also has issues. If time were always broadcast in TAI, and if the number of leapseconds was always available, then these issues would go away. But it isn't. As the number of these issues you try to code around grows, the complexity reaches a point where you say geeze, this was a stupid idea. Warner ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 02/08/2011 17:19, Steve Allen wrote: On Tue 2011-02-08T17:03:31 -0700, Warner Losh hath writ: NTP also does everything in UTC time No, NTP does not use UTC per se. The existing implementations make that specification misleading. Rather, NTP uses the internationally approved broadcast time scale. The implementations do not know the name of that time scale. Only the documentation knows that. (This is, of course, discounting those site whose sensitivity to leap seconds is so great that they are using some sort of GPS-based or TAI-based master timeserver for their NTP.) Pedantically correct, but ntp networks operating in those modes are the exception, rather than the rule. At least with the prevalence of GPS-based ntp-servers, setting up a GPS-time network is quite a bit easier to pull off than years ago... The point of my suggestion for using zoneinfo to propagate the leap seconds is that both NTP and POSIX would de facto, silently, and inconsequentially change to using TI rather than UTC if the name of the internationally approved time scale changed to that. The systems would keep working just fine -- even better if they do not like leaps. Yes, that would work. If there were no more leap seconds then this would be a workable solution. only because you don't have either the restart or the stale leap data to worry about. The documentation could be fixed up later, and the situation would not be any more confusing than it is now. The biggest problem I have with the current state of the art is the need to restart programs when new zone files arrive. At least that was the state of the art last time I studied this code in detail, which was about 3 years ago. The second biggest problem I have is using stale leap second data to do things like set the current system time before you can get the latest info, at which point you're painted into a corner with few good solutions. Warner -- Steve Allens...@ucolick.org WGS-84 (GPS) UCO/Lick ObservatoryNatural Sciences II, Room 165Lat +36.99855 University of CaliforniaVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On Tue 2011-02-08T21:56:35 +, Poul-Henning Kamp hath writ: If you read the minutes of the conference, you will find that at best it amounts to a joint proposal on terms of reference for geographical coordinates, and that serveral questions of timekeeping specifically a declared out of scope along the way. The fact is that another generation will have to die before the teachers, students, textbooks and software written by them get accustomed to the fact that time is not longitude. Since then the longitude and latitude has moved into the care of whoever it is that defines things lige WGS84 and the second has moved into BIPM's basement. longitude and latitude belong to the IERS. So substance wise, there is as far as I can tell nothing left of the 1884 conference, apart from the heartfelt thanks to the US president for calling and hosting the conference. It is the context for understanding other things. Further evidence of this is that UN registers all internation treaties its member states have entered into, in accordance with the UN charters article 102, and you can see all of these treaties at http://treaties.un.org In there I do not find the ITU-R's Radio Regulations, so perhaps the whole point of this mail list is moot, for we are not bound to follow them? In there I also do not find Meter Convention, so perhaps the UN list is not comprehensive. The Meter Convention does say this http://www1.bipm.org/jsp/en/ViewCGPMResolution.jsp?CGPM=15RES=5 and the context for that is CCIR Recommendation TF.460-1. I believe that revision of TF.460 specifies a tolerance of 1 second as well as saying GMT. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick ObservatoryNatural Sciences II, Room 165Lat +36.99855 University of CaliforniaVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] What's the point?
On 8 Feb 2011, at 17:05, Gerard Ashton wrote: Sovereign states have some degree of control over civil time; the remaining control is in the control of individuals, either through personal whims or voluntary collective action. The IAU, ITU, BIPM, ISO, and all the rest do not have control over civil timekeeping because the weights and measures inspectors who enforce measurement laws do not take orders from them, they take orders from the sovereign state that employs them. Although it's not obvious to me that in the UK, at least, they have any practical authority over time. The Weights and Measures Act 1985 S.6(1)(c) makes it clear that they could check clocks (or at least the interval measuring aspect of them) if someone asked them to: 6Testing of other standards and equipment. (1)The Secretary of State may, if he thinks fit, on the application of any government or person, accept for testing as to accuracy or compliance with any specfication and for report— (a)any article used or proposed to be used as a standard of a unit of measurement of mass, length, capacity, area or volume, or as a standard of the weight of any coin, (b)any weighing or measuring equipment, (c)any other metrological equipment, and (d)any article for use in connection with equipment mentioned in paragraph (b) or (c) above, submitted by that government or person for the purpose at such place as the Secretary of State may direct. But the rest of the act is mostly about weighing, which conflates force and mass but I think we know what they mean, and measuring, which for these purposes usually means of length and powers of length. For example, Schedule 1 defines units of length, mass, volume and area, with the second used (to define metres in terms of the speed of light) but not defined. The schedule does also has some electrical units, because weights and measures officers' remit does run to checking electricity meters, but again the definitions depend on the (undefined) second, to get to the Watt. But there's no mention of electricity in the body of the act, not of clock, and a quick glance (not exhaustive) implies the word time is always use in such constructions as at such time as, not in terms of anything that might be measured. I can conceive of all sorts of scenarios in which either the rate or the absolute value of clocks might be a TS issue. Charging bands for telephone calls or electricity (at the moment there are two bands, but there's talk about more), congestion charging, car park fees, etc, etc. But cases that actually come to court seem to be fairly thin on the ground. ian ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
