[More NOISE, skip reading if you want SIGNAL] On Jan 24, 2011, at 5:36 AM, Christian Huitema wrote: >> Wasn't the official definition of the meter also tied to Paris? > > The invention of the meter is indeed tied to Paris. The value of the meter itself is not. > > The meter was defined by scientists commissioned by the French revolutionary assembly, but it is not exactly "tied to Paris." The original definition was 1/10,000,000 of a quarter of the Earth circumference, and the commission of scientists established the value by measuring an arc of the earth circumference between North of France and North of Spain. The unit was then materialized by a big platinum ruler kept in a locker in Paris. It is now defined in relation to the speed of light, itself set as 299,792,458 meters per second. > Reminds me of an excellent story where Superdupont saved the world from misery when a bunch of International Terrorists (with British and German accents) saved replaced the standard meter by a non-standard. http://en.wikipedia.org/wiki/Superdupont Since we are exchanging pedantic wise cracks. Instead of Platinum, we now find Cesium to be at the hearth of the measurement of a meter: 299,792,458 meters per 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. Earlier PhB wrote: > The idea that there is utility in leap seconds is ridiculous. Most astronomers I have talked to tell me that UTC is useless for their purposes anyway and the time of mid-day varies at Greenwich by 5 minutes over the course of a year so what does it matter which two days are right? Julian Date is the date mostly used in observation records etc. (at least when I did my observing runs as a graduate student). The convenience of the Julian date is that you just keep counting, the Unix time guys did the same, except that there NULL epoch was in 1970 instead of 4713 BC and the unit of counting is seconds instead of days (roughly). PhB also said: > What else is there to discuss in Paris? I vividly remember http://www.ietf.org/mail-archive/web/ietf/current/msg36670.html so those discussion may eventually contribute to more noise on the IETF list. --Olaf ________________________________________________________ Olaf M. Kolkman NLnet Labs Science Park 140, http://www.nlnetlabs.nl/ 1098 XG Amsterdam
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