Re: [LEAPSECS] Leap smear
On 19 Sep 2011, at 1446, Rob Seaman wrote: If you don't believe that civil time is time-of-day where day means synodic day, then assert an alternate definition for what the word day means. Then we can debate the two alternatives head-to-head independent of the complexity of how different deployed solutions will address the requirements. Clive's man on the Clapham Omnibus probably realises that timezones are a fiction, and are a discrete approximation to a continuous function (although he won't describe it like that). He might have a dim memory from school of being told about towns having their own time and standardisation coming with the railways. He'll be aware that sundials usually don't agree with his watch, and that when he crosses the channel the sun doesn't suddenly step in the sky. It might even have occurred to him that one reason the evenings are longer in Cornwall is that you're well to the west of London. Certainly, explaining those things is not difficult. In America, or mainland Europe, where you can drive your car across a timezone boundary whilst looking out of the window, he'll be even more aware that they're an approximation. Even if he doesn't know these things, English law's well-known reasonable man would not find it hard to understand that his watch ticking the same time in Norwich as in Penzance is a convenient way to make sure that he can turn the radio on in time for The Archers, but that the sun rises and sets at different times within that time zone. Therefore, he'll be able to understand that he's already accepting up to two hours' disconnect --- one for the width of the time zone, one for daylight saving --- between civil time and solar time. And he might even realise that his holiday home in Brittany (4' 20W, UTC+2 in summer) is an even more dramatic example. So he's going to be pretty resistant to the idea that a few seconds a decade matters in the slightest.Civil time is what his watch says. He already knows civil time isn't solar time. So shouting that there's a risk that civil time is going to unhitch from solar time by around a minute a century and the sky is going to fall isn't going to frighten him. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
Warner Losh i...@bsdimp.com wrote: Not at all a red-herring, but rather making a subtle point that we've already moved off of apparent solar time. We're not even using mean solar time, but mean solar time at some arbitrary location. Each step is a step away from being tied to the sun. There are many more steps possible, up to and including just going with atomic time and forgetting the sun. There's also the fact that people naturally prefer to sync their activities to sunrise or sunset, so timetabling everything to mean solar time is a very awkward imposition. This is why daylight saving time exists, because astronomical time isn't convenient. Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ Thames, Dover, Wight: Southwest 5 to 7. Moderate, occasionally rough. Rain later. Moderate or good, occasionally poor later. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
In message 5739cd71-48b7-4f98-9ba5-93f0daab0...@noao.edu, Rob Seaman writes: The whole point of DST is an adjustment from a norm. Now you are making even less sense than usual. The whole point of DST is not adjustment from a norm, that would be rulemaking for rulemakings sake. The whole point of DST are some vague economical and dubious quality-of-life arguments, and it has absolutely nothing to do with leap seconds, except to show that A) Changes to civil time are not only feasible but also relatively painless, provided computers are programmed to deal correctly with it. B) Earth Orientation is not important at sub-half-hour precision. -- 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] Leap smear
On Sep 20, 2011, at 11:02 AM, Ian Batten wrote: On 20 Sep 2011, at 1036, Rob Seaman wrote: Ask yourself if your position is really that clocks could tick at any randomly chosen rate picked out of a hat? No-one's saying that. If you're asking the question could civil clocks tick at any randomly chosen rate that is within 1ppm of what astronomers say it should be then the answer is yes. Ok. So the assertion is that 1 ppm is acceptable. Systematic errors are different than random errors (however distributed), but let's ignore that not so minor distinction. Let's see…1 ppm is 0.0864 seconds per day. That is a leap second (or equivalent drift) every 11.57 days. A leap hour (presuming such is implementable) every 114 years. Is this acceptable? Says who? What process should be followed? Who should be consulted? If the answer is easy - then it's easy to write it down. So let's say consensus is reached on 1 ppm, or maybe 10 ppm or 0.1 ppm. What is this tolerance measured against? Right! Time-of-day = mean solar time. What is LOD in all those plots? Requirements describe the problem space. Mean solar time is a requirement. 1 ppm would be a specification against a proposed solution suitable for evaluation by a trade-off, risks, costs, schedule, sensitivity analyses, etc. Glad to see consensus that clocks cannot actually tick at any old rate. What can we reach consensus on next? What process most efficiently promotes consensus? Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
Let's see…1 ppm is 0.0864 seconds per day. That is a leap second (or equivalent drift) every 11.57 days. A leap hour (presuming such is implementable) every 114 years. Is this acceptable? Says who? What process should be followed? Exactly the same process that the UK followed on the 27th of October 1968. You wouldn't be leaping UTC, you'd be leaping civil time. We're used to that. You just spring forward, but don't fall back. Need the leap hour in the opposite direction? Don't spring forward, but leap back, as we did on 31st October 1971. What's so difficult about it? Changing timezones by an hour has happened with monotonous regularity: Portugal's done it several times, for example. Britain's tried UTC+0/UTC+1 (most commonly), UTC+1 (British Standard Time, 1968--71), UTC+1/UTC+2 (British Double Summer Time, 1940--1945), and UTC+0/UTC+2 (1947), so four civil time standards in the lifespan of people still alive. There are many arguments why the proposal to move the UK (or at least not-Scotland's) time to align with mainland Europe is a good one, and some why it's a bad one, but no-one sane has attempted the oh, correcting our watches is really hard because people will just laugh. There's been multiple leap-hours in my lifetime, including one-off ones, are likely to be more, and within my parents' lifetime there's been leap-two-hours, twice. Why is one extra leap-hour per century any different? ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
So let's say consensus is reached on 1 ppm, or maybe 10 ppm or 0.1 ppm. What is this tolerance measured against? Right! Time-of-day = mean solar time. What is LOD in all those plots? Requirements describe the problem space. Mean solar time is a requirement. 1 ppm would be a specification against a proposed solution suitable for evaluation by a trade-off, risks, costs, schedule, sensitivity analyses, etc. So why aren't all those exotic investigations necessary when countries change timezones, which happens with monotonous regularity?In this case, no-one is proposing to change the SI second, rather just to use it as monotonic counter. We've already established that the link between civil time and solar time has an uncertainty measured in multiple minutes, and we've already established that one-hour steps in civil time are trivial to implement, because they happen twice a year. All we're left with is a vague need to keep the sun roughly overhead at noon (although there are few riots in Brest, France, which in the summer is about 2hr10 unhitched from solar time) which we can manage with daylight saving time type adjustments. The rest is just sky is falling stuff,. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On 20 Sep 2011 at 12:09, Ian Batten wrote: You wouldn't be leaping UTC, you'd be leaping civil time. We're used to that. Though we're not used to any local civil times being over 24 hours removed from UTC, which would happen eventually after a few millennia of UTC being uncoupled from solar time. -- == Dan == Dan's Mail Format Site: http://mailformat.dan.info/ Dan's Web Tips: http://webtips.dan.info/ Dan's Domain Site: http://domains.dan.info/ ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On 2011 Sep 20, at 04:15, Ian Batten wrote: So why aren't all those exotic investigations necessary when countries change timezones, which happens with monotonous regularity? It's a matter of representation. In that case the offset is 1) obvious to any human and customary already for a century 2) completely handled by the tz folks in the zoninfo code and database Arbitary offsets between civil time and the underlying representation are a solved problem. Furthermore, Arthur David Olson has managed the sociology of creating a civil time community which is itself civil. I think we could learn several things from them. -- Steve Allen s...@ucolick.org WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855 University of California Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
In message 4e78aa49.5060...@comcast.net, Gerard Ashton writes: On 9/20/2011 5:53 AM, Poul-Henning Kamp wrote: Earth orientation is one factor in the time of sunrise and sunset, and that is important at perhaps minute precision for many purposes, such as avoiding violation of laws regarding turning on automobile headlights, and the taking of game. Show one single court-case, where the exact time of sunrise or sunset has been a crucial factor, with a precision better than three minutes, and I'll belive you. -- 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] Leap smear
On 20 September 2011 13:51, Daniel R. Tobias d...@tobias.name wrote: You wouldn't be leaping UTC, you'd be leaping civil time. We're used to that. Though we're not used to any local civil times being over 24 hours removed from UTC, which would happen eventually after a few millennia of UTC being uncoupled from solar time. Yes, the tzdata offset solution has odd consequences. Many people know and use the +01:00 notation for Paris or -05:00 notation for New York. Having those start changing dramatically isn't appealing to me... +37:00 for Paris anyone? I'd also note that plenty of code/standards assumes that the offset is limited in range, such as -14:00 to +14:00. There is a cost to change right there. Plus, there is another more subtle down side. By using tzdata for this, it places the control in the hands of politicians. Whereas, up until now, the core definition of civil time (GMT/UTC) has essentially been controlled by scientists and technologists (sure you might argue on some finer details in that claim, but in broad brush I'd argue it is very true). Personally, I think it would be very unwise to give up control to politician of the core clock that is used by the world's population (yes, UTC would still be driven by science, but it would be irrelevant to real people, in the same way that TAI is today). Saying that people just care about the time on the news or their wall isn't enough - they do care about offsets too, and decoupling those from anything meaningful is just asking for trouble. Stephen ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On 20 Sep 2011, at 16:51, Gerard Ashton wrote: On 9/20/2011 11:24 AM, Poul-Henning Kamp wrote: In message4e78aa49.5060...@comcast.net, Gerard Ashton writes: On 9/20/2011 5:53 AM, Poul-Henning Kamp wrote: Earth orientation is one factor in the time of sunrise and sunset, and that is important at perhaps minute precision for many purposes, such as avoiding violation of laws regarding turning on automobile headlights, and the taking of game. Show one single court-case, where the exact time of sunrise or sunset has been a crucial factor, with a precision better than three minutes, and I'll belive you. I have no way to document the hunters who refrained from taking a deer one minute after what the hunter believed to be the legal hunting hours expired. Has anyone ever been prosecuted for taking a deer one minute after the legal hunting hours expired? Two minutes? Lighting up time in the UK, at least, has fallen into disrepair. It's no longer published in newspapers with anything like the prominence that it once was, and if you drove around in a car 29 minutes after sunset without your lights on the police would stop you on general principles, as the legislation covering the requirement to make yourself visible in low visibility would override any debate about lighting up times. I doubt anyone under fifty would even have heard of the concept, often than in some general sense of the evening. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On Sep 20, 2011, at 9:51 AM, Gerard Ashton wrote: On 9/20/2011 11:24 AM, Poul-Henning Kamp wrote: In message4e78aa49.5060...@comcast.net, Gerard Ashton writes: On 9/20/2011 5:53 AM, Poul-Henning Kamp wrote: Earth orientation is one factor in the time of sunrise and sunset, and that is important at perhaps minute precision for many purposes, such as avoiding violation of laws regarding turning on automobile headlights, and the taking of game. Show one single court-case, where the exact time of sunrise or sunset has been a crucial factor, with a precision better than three minutes, and I'll belive you. I have no way to document the hunters who refrained from taking a deer one minute after what the hunter believed to be the legal hunting hours expired. The hunters in the US that I know that deal with sunrise/sunset laws deal with it by going Yup, I could still see, sun must have been up. or No, it was starting to get a little dark. I don't know anybody that's out in the back country with sunrise/sunset tables and a watch that's accurate to more than 5 minutes unless they are using one of these new-fangled GPS receivers. Then again the laws about hunting in the US that I'm familiar with tend to be dusk/dawn laws not sunrise/sunset laws. Mostly because sunset is hard to observe in the bottom of a valley with irregular mountains all around, but dusk is easier to know (which likely explains the heck, it ain't dark, I didn' t need a flashlight to see the deer well enough to shoot it attitude). Warner ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On 20 September 2011 17:04, Ian Batten i...@batten.eu.org wrote: Yes, indeed, if we allowed leap seconds to build up at the current rate, there would be an issue with an additional hour being required in the range of timezones in approximately five and a half thousand years' time (one leap second per eighteen months, times 3600 seconds per hour). Five and a half thousand years ago is somewhere around the boundary between the neolithic and the bronze age, and the rate of technological change is accelerating, not slowing. I can think of few things I care about less than people in five thousand years' time having to revise the Olson tz code. http://www.ucolick.org/~sla/leapsecs/dutc.html#dutctable Looks like it could be 400-900 years to the first hour. Personally, I think it would be very unwise to give up control to politician of the core clock that is used by the world's population (yes, UTC would still be driven by science, but it would be irrelevant to real people, in the same way that TAI is today). Saying that people just care about the time on the news or their wall isn't enough - they do care about offsets too, and decoupling those from anything meaningful is just asking for trouble. Could you outline the sort of trouble you have in mind? My assessment is that most people (which thus includes politicians) don't generally trouble themselves with the finer details of standards or technology so long as it works in a way that is reasonably in tune with their basic expectations. The problems occur (cursing, annoyance or political pressure) when things are in some way out of kilter with those basic expectations. Today's UTC offset system is easy enough to explain - its the number of hours time difference of our local area to the 'standard' solar day in the UK. Vague? Yes. Imprecise? Yes. But it doesn't matter, as a general explanation - people feel that they have a *basic* handle on how the clock and the offset work, and it seems enough like common sense for them to be comfortable. However, the tzdata approach ends up with no meaningful common sense definition. The offset becomes an ever increasing offset to some arbitrary clock to the length of day 500+ years ago that a bunch of time nerds back then was more important that the length of the solar day. I posit that people would be uncomfortable about that lack of ability to link the concept of time and offset to something meaningful, like a solar day. And if people are uncomfortable, then politicians become uncomfortable. Perhaps, one or more countries would redefine time completely as a result, who knows... Now, if those supporting this proposal are wililng to say publicly that it basically punts the problem to future generations and that they don't care what those generations do, then they'd be being more honest. Stephen ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On Sep 20, 2011, at 10:13 AM, Greg Hennessy wrote: Yes, indeed, if we allowed leap seconds to build up at the current rate, there would be an issue with an additional hour being required in the range of timezones in approximately five and a half thousand years' time (one leap second per eighteen months, times 3600 seconds per hour). Of course leap seconds are expected to build up much more rapidly than that, they are expected to increase quadradically. Of course. You can see the progress in http://www.ucolick.org/~sla/leapsecs/dutc.html for various acceleration rates. Numbers turn out to be closer to 500-700 years for a 30 minute offset and 800-1000 for a 1 hour offset. 5k years out would be a ~8-12 hour delta. The reason for the ranges is that we don't known which numbers to use for long term projects. Recent history shows a much faster rate of change than the long term average from 1620 when good records first become available. The long-term records from events like eclipses, though less accurate, show a lower rate of change. (25.6s/century^2 vs 42s/century^2). To put things in perspective, ~700AD to the present has accumulated 1 hour. Warner ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On Sep 20, 2011, at 10:33 AM, Gerard Ashton wrote: So we have no choice but to suppose that the letter of the law/rule/regulation/standard is important, else why bother to establish the law/rule/regulation/standard in the first place. We do have a choice. The letter of the law/regulation is sometimes followed very carefully. Other times it is a codification of what seemed to be a reasonable approximation. With hunting, day hunting is different than night hunting. Night hunting is generally frowned upon because it makes it too easy to take the animals, too hard for game wardens to enforce the rules and too easy to shoot your fellow man thinking he was a 40-point buck. While dawn/dusk has more wiggle room in it than sunrise/sunset would on the planes, in the mountains, they are easier to police. Both are approximations of the well, you should only hunt when it is light enough and nobody carries around tables of times and everybody generally agrees when it is dusk or dawn. They could have written the rules to say You can only hunt when the ambient light from the sun is more than so many candelas which makes any time tinkering irrelevant. But such a technical refinement of the rules may lead to other unintended consequences, or it may have no practical effect at all. It is hard to say. Warner ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On Tue 2011-09-20T17:50:05 +0100, Ian Batten hath writ: You cannot imagine how little most people care about the magnitude of DUT1 in five hundred years' time. That was the attitude of factories about dumping mercury into the Rhine. It turned out to be something people did come to care about. So we also cannot imagine how much they will care about the underlying basis for civil time in 500 years. What we know now is that all existing agreements on the notion of UTC have been established with the explicit acknowledgement that it represents mean solar time. This starts with 1884 and continues through the very documents which the CCIR published about UTC. At the CCIR Plenary Assembly in 1978 when CCIR Rec. 460-2 were published the supporting documentation literally rejoices at the 1975 CGPM resolution which says that UTC is mean solar time. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165Lat +36.99855 1156 High StreetVoice: +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] Leap smear
On Sep 20, 2011, at 10:43 AM, Stephen Colebourne wrote: However, the tzdata approach ends up with no meaningful common sense definition. The offset becomes an ever increasing offset to some arbitrary clock to the length of day 500+ years ago that a bunch of time nerds back then was more important that the length of the solar day. I posit that people would be uncomfortable about that lack of ability to link the concept of time and offset to something meaningful, like a solar day. And if people are uncomfortable, then politicians become uncomfortable. Perhaps, one or more countries would redefine time completely as a result, who knows... Roads today are the size they are due to horses asses. That doesn't seem to bother people. They don't care that the size of the roads were basically set in roman times to accommodate carts drawn by horses two abreast. This standard persisted after the fall of the roman empire because the roads were there and all the people that knew how to make carriages kept making them the same size, so any new roads had to be made the same size as the old roads. When it came time to make the first trains, they were made by the carriage makers, to the standard gage for trains was approximately what the size of a road had been. In a similar vein, the roads we drove on today are the size they are because the first cars were little more than motorized carriages, also made by the same folks. Never under-estimate the reason We base the time off of time in england back in the nineteenth and twentieth centuries, but the earth has slowed down a bit, so the details are messy even though we still use that same basic scheme. coupled with tradition. Heck, that's why we use the definition of a second that makes this problem happen every couple of years instead of every few decades. We use a second which is the length of time of a particular fraction of a mean solar year in 1820. Warner ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Legal violation for failure to know sunrise/sunset to nearest minute
On Tue 2011-09-20T13:18:15 -0400, Gerard Ashton hath writ: Of course, discovering if the rules are actually enforced as rigorously as indicated by the spokeswoman would be an enormous effort, visiting the locations where the relevant court cases are stored and searching through them, or conducting polls of hunters and/or game wardens. Yet this is pretty much what Arthur David Olson and Paul Eggert have orchestrated in the tz mail list as those members comb through the various bureaucratic, legislative, administrative mazes of every jurisdiction tracking whether and when decrees have actually been issued and whether the local residents conform or not. Neverminding the political and territorial squabbles that accompany all the changes, they succeed. The technical ability to keep UTC as a timezone distinct from an underlying uniform broadcast is demonstrated. The political will to conform to existing treaties and resolutions is not evident. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165Lat +36.99855 1156 High StreetVoice: +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] Leap smear
In message ad679e84-72ae-4f73-8366-404f9cfcb...@bsdimp.com, Warner Losh write s: Both are approximations of the well, you should only hunt when it is light enough and nobody carries around tables of times and everybody generally agrees when it is dusk or dawn. In Denmark we actually have a several centuries old legal definition of dusk and dawn, promulgated by none other than Astronomer Ole Römer: Civil twilight: Sun less than 6 degrees under the horizon Nautical twilight: Sun less than 12 degrees under the horizon Astronomical twilight: Sun less than 18 degrees under the horizon -- 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] Leap smear
On Tue, Sep 20, 2011 at 3:11 AM, Ian Batten i...@batten.eu.org wrote: Civil time changes by an hour every six months. The idea that timezones will have to change by an hour in a thousand years' time isn't going to frighten anyone. I apologize for my ignorance. What does civil time changes by an hour every six months mean? ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On 20 Sep 2011, at 1808, Steve Allen wrote: On Tue 2011-09-20T17:50:05 +0100, Ian Batten hath writ: You cannot imagine how little most people care about the magnitude of DUT1 in five hundred years' time. That was the attitude of factories about dumping mercury into the Rhine. It turned out to be something people did come to care about. So we also cannot imagine how much they will care about the underlying basis for civil time in 500 years. That's a universal argument: it can be used to say that we shouldn't build the LHC, that we shouldn't add variable sized arrays to C, that we shouldn't get up tomorrow. It's difficult to remove Hg from the environment for solid reasons about energy and dilution. You can add or remove leap seconds with the stroke of a pen. They aren't comparable. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On 20 Sep 2011, at 2011, Doug Calvert wrote: On Tue, Sep 20, 2011 at 3:11 AM, Ian Batten i...@batten.eu.org wrote: Civil time changes by an hour every six months. The idea that timezones will have to change by an hour in a thousand years' time isn't going to frighten anyone. I apologize for my ignorance. What does civil time changes by an hour every six months mean? Daylight saving. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On Tue, Sep 20, 2011 at 3:36 PM, Ian Batten i...@batten.eu.org wrote: On 20 Sep 2011, at 2011, Doug Calvert wrote: On Tue, Sep 20, 2011 at 3:11 AM, Ian Batten i...@batten.eu.org wrote: Civil time changes by an hour every six months. The idea that timezones will have to change by an hour in a thousand years' time isn't going to frighten anyone. I apologize for my ignorance. What does civil time changes by an hour every six months mean? Daylight saving. Some civil time scales change by an hour every six months. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
On 20 Sep 2011, at 21:14, Doug Calvert wrote: On Tue, Sep 20, 2011 at 3:36 PM, Ian Batten i...@batten.eu.org wrote: On 20 Sep 2011, at 2011, Doug Calvert wrote: On Tue, Sep 20, 2011 at 3:11 AM, Ian Batten i...@batten.eu.org wrote: Civil time changes by an hour every six months. The idea that timezones will have to change by an hour in a thousand years' time isn't going to frighten anyone. I apologize for my ignorance. What does civil time changes by an hour every six months mean? Daylight saving. Some civil time scales change by an hour every six months. There exists at least one civil time scale in an advanced economy that changes by an hour every six months. That is sufficient for my point. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Legal violation for failure to know sunrise/sunset to nearest minute
On 9/20/2011 3:38 PM, Ian Batten wrote: They're hardly going to say we publish the regulations, but don't worry, we don't enforce them, are they? If they're enforced to the nearest minute, it shouldn't be hard for them to find a court case in which they were enforced to the nearest minute. I'm inclined to agree with They're hardly going to say 'we publish the regulations, but don't worry, we don't enforce them', are they? but that is just my own personal perception of how government agencies work; I have not a shred of proof. I strongly disagree with If they're enforced to the nearest minute, it shouldn't be hard for them to find a court case in which they were enforced to the nearest minute. So far as I know, such cases are not available online. My understanding is that only appellate court decisions are online, and then, only the most important appellate courts, or recent cases. I would not be surprised if the basic facts, such as a person of a certain name being convicted of a certain offense on a certain date being available in some kind of log or index at the courthouse, but the details of the case, such as how many minutes elapsed from the close of legal hunting hours to the time of the offense could be contained on a tape recording of the trial, perhaps never having been put in text form. Of course, if there is a search strategy I'm overlooking, feel free to point it out. Gerard Ashton ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Legal violation for failure to know sunrise/sunset to nearest minute
On 20 Sep 2011, at 2221, Gerard Ashton wrote: but the details of the case, such as how many minutes elapsed from the close of legal hunting hours to the time of the offense could be contained on a tape recording of the trial, perhaps never having been put in text form. It seems unlikely that people would be being convicted on the basis of a one-minute transgression and it not be reported in a newspaper, a magazine relating to (in this case) hunting, or blogs on the topic, or the accused's own blog, and that no-one has appealed it, offered it as an example in a how to not get arrested while hunting book, etc, etc, etc. Were it a parking offence it would make the local papers. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap smear
However, the tzdata approach ends up with no meaningful common sense definition. The offset becomes an ever increasing offset to some arbitrary clock to the length of day 500+ years ago that a bunch of time nerds back then was more important that the length of the solar day. I posit that people would be uncomfortable about that lack of ability to link the concept of time and offset to something meaningful, like a solar day. Time zones don't make sense until somebody explains that the Earth is a sphere and rotates about its axis and such. We don't have much troubles with them. It's only one more step to explain that the rotation rate is decaying and that the length of the second that they picked way back when doesn't quite match a normal day any more and that here is this neat graph of the differences... I'll bet third graders would pick it up. [I'm not saying we should drop leap seconds, just that I don't think that common sense is a good enough reason to not do it.] -- These are my opinions, not necessarily my employer's. I hate spam. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
