Re: [LEAPSECS] Worlds apart
On 28 Oct 2014, at 00:46, Rob Seaman sea...@noao.edu wrote: Their actions should aspire to agree with physical reality. Anything which alludes (whether intentionally or unintentionally) to Feynman's magisterial dissection of the Shuttle programme is OK by me! For a successful technology, reality must take precedence over public relations, for nature cannot be fooled. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] the big artillery
Just after the WP7A activity in Geneva earlier this month the CGSIC declared that leap seconds are unacceptable risk. http://www.gps.gov/cgsic/timing/2014-resolution/ Their history neglects that initial need for leap seconds was to satisfy the demands of the IAU and navigation community that the radio broadcast time signals *must* provide Universal Time. I wonder if the ITU-R process can go to its completion without introducing any document which points out that to omit leap seconds from a time scale called UTC is to redefine the word day. -- 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 https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] the big artillery
In message 20141030143121.ga20...@ucolick.org, Steve Allen writes: I wonder if the ITU-R process can go to its completion without introducing any document which points out that to omit leap seconds from a time scale called UTC is to redefine the word day. You mean the same way leapseconds redefine minute by making them have the counter intuitive numbers of seconds ? -- 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 https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] the big artillery
Day is a fundamental physical fact about a planet or moon. Minute is an artificial concept. Its intuitive role as a fraction of a day takes precedence over serving as a round number of equally artificial SI seconds. There are two kinds of time that must be accommodated. Rob Seaman NOAO -- On Oct 30, 2014, at 8:06 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 20141030143121.ga20...@ucolick.org, Steve Allen writes: I wonder if the ITU-R process can go to its completion without introducing any document which points out that to omit leap seconds from a time scale called UTC is to redefine the word day. You mean the same way leapseconds redefine minute by making them have the counter intuitive numbers of seconds ? ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] the big artillery
I see Terrestrial Time being expressed as a Julian Date quite a lot. What is the unit of that number if not Day? Dennis Ferguson On 30 Oct, 2014, at 09:16 , Rob Seaman sea...@noao.edu wrote: Day is a fundamental physical fact about a planet or moon. Minute is an artificial concept. Its intuitive role as a fraction of a day takes precedence over serving as a round number of equally artificial SI seconds. There are two kinds of time that must be accommodated. Rob Seaman NOAO -- On Oct 30, 2014, at 8:06 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 20141030143121.ga20...@ucolick.org, Steve Allen writes: I wonder if the ITU-R process can go to its completion without introducing any document which points out that to omit leap seconds from a time scale called UTC is to redefine the word day. You mean the same way leapseconds redefine minute by making them have the counter intuitive numbers of seconds ? ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] the big artillery
Well, for historical and archival purposes Julian date nearly always means traditional days, as in solar days. But for astronomical uses a fixed unit, the apocryphal atomic day is implied. This means needing to know delta T if you need to relate it back to a civil date or time. The term 'day' has an awful lot of linguistic baggage that clearly implies that the solar day is meant. But now the use of 'day' can be at the speaker's and listener's risk. The minute, hour, day, year... these are not SI units. We need to start considering it sloppy to use them as if they are. Do we mean 'atomic day'? If so we need to: 1. say so, and 2. make it official by defining, rather than just implying one. Perhaps hectosecond would be better. At least it doesn't invite confusion. Yeah, and now to convince anyone to do this. Richard Clark On Thu, 30 Oct 2014, Dennis Ferguson wrote: I see Terrestrial Time being expressed as a Julian Date quite a lot. What is the unit of that number if not Day? Dennis Ferguson On 30 Oct, 2014, at 09:16 , Rob Seaman sea...@noao.edu wrote: Day is a fundamental physical fact about a planet or moon. Minute is an artificial concept. Its intuitive role as a fraction of a day takes precedence over serving as a round number of equally artificial SI seconds. There are two kinds of time that must be accommodated. Rob Seaman NOAO -- On Oct 30, 2014, at 8:06 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 20141030143121.ga20...@ucolick.org, Steve Allen writes: I wonder if the ITU-R process can go to its completion without introducing any document which points out that to omit leap seconds from a time scale called UTC is to redefine the word day. You mean the same way leapseconds redefine minute by making them have the counter intuitive numbers of seconds ? ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] the big artillery
Poul-Henning Kamp writes: In message 20141030143121.ga20...@ucolick.org, Steve Allen writes: I wonder if the ITU-R process can go to its completion without introducing any document which points out that to omit leap seconds from a time scale called UTC is to redefine the word day. You mean the same way leapseconds redefine minute by making them have the counter intuitive numbers of seconds ? I don't see this as the same thing. If this argument is valid then leap years are also problematic. I'm still thinking the answer is leave existing 'names' alone - if you want TAI use TAI. If you want UTC, use UTC. If you want something new, call it something new. If people are using a defined name for a defined purpose and it works for them, leave it alone. If people are using a defined name for a defined purpose and it does not work for them, this group needs to come up with a new name for the thing they think will solve their problems. -- Harlan Stenn st...@ntp.org http://networktimefoundation.org - be a member! ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] the big artillery
Harlan Stenn said: I'm still thinking the answer is leave existing 'names' alone - if you want TAI use TAI. If you want UTC, use UTC. If you want something new, call it something new. If people are using a defined name for a defined purpose and it works for them, leave it alone. If people are using a defined name for a defined purpose and it does not work for them, this group needs to come up with a new name for the thing they think will solve their problems. The problem is that some people use UTC to mean TAI plus adjustments to keep it less than a second from UT1 while other people use UTC to mean the basis of legal time here. For the second set, using a new name for a different concept doesn't help. There are good reasons for wanting legal time to be TAI+n+local offset, where n is a constant (somewhere around 35?) that never changes in the future and local offset is chosen by the relevant lawmakers and is normally a multiple of 15 minutes. If you accept that these reasons override those for keeping leap seconds, then a name change won't make it easy. -- 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 https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] the big artillery
Clive D.W. Feather writes: Harlan Stenn said: I'm still thinking the answer is leave existing 'names' alone - if you want TAI use TAI. If you want UTC, use UTC. If you want something new, call it something new. If people are using a defined name for a defined purpose and it works for them, leave it alone. If people are using a defined name for a defined purpose and it does not work for them, this group needs to come up with a new name for the thing they think will solve their problems. The problem is that some people use UTC to mean TAI plus adjustments to keep it less than a second from UT1 while other people use UTC to mean the basis of legal time here. For the second set, using a new name for a different concept doesn't help. That some people are mis-using a name is not the fault of the name. There are good reasons for wanting legal time to be TAI+n+local offset, where n is a constant (somewhere around 35?) that never changes in the future and local offset is chosen by the relevant lawmakers and is normally a multiple of 15 minutes. If you accept that these reasons override those for keeping leap seconds, then a name change won't make it easy. UTC has leapseconds, and people who are using UTC for its intended purpose are happy. If there are people who want a similar timescale that does not use leapseconds, that's great, and come up with a different name for this timescale that does not use leapseconds. H ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] the big artillery
On Fri, Oct 31, 2014 at 7:01 AM, Harlan Stenn st...@ntp.org wrote: I'm still thinking the answer is leave existing 'names' alone - if you want TAI use TAI. If you want UTC, use UTC. If you want something new, call it something new. If people are using a defined name for a defined purpose and it works for them, leave it alone. If people are using a defined name for a defined purpose and it does not work for them, this group needs to come up with a new name for the thing they think will solve their problems +1 I understand the issue that UTC is a part of many laws and documents that will be difficult to change, so it is easier to change the definition of UTC. But this still does not make it right. As an extreme example, and more in jest, consider if a number of legislatures enacted laws to make maths simpler, by declaring that the adjustments past the second decimal place to pi need not apply, and hence pi will be fixed at 3.14. This will save lots of time and effort, and help programmers and implementers make fewer mistakes. Will we, because it is hard to get governments to make changes, say, OK, pi = 3.14, and any one (like Rob) who still wants the old figure can look up the correction from IAU (but not call it pi)? I know this is an inexact analogy. When it was realised that the it was easier to work with a value of (Planck Constant / 2 pi), that (h-bar) was not renamed to by the Plank Constant, it has a new name: Dirac Constant or Reduced Planck Constant. We use the h-bar more often, but do not re-purpose the original name. Give it a new name, please. Independent of what the fundamental unit is. -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
