Dear John, I agree with your thoughts below. My simple addition is to remark that SI is 'supported' it is 'coherent' and it is a 'system'. This means that all of its units are inter-related. A change to one means a change to all.
If you change the second, the metre also changes, m/s changes. m/s^2 changes, kg.m/s^2 (newton) changes as do all other international standards, in all crafts, trades, and professions They would all have to change to suit the 'new' second. It is simply not worth any of this effort to have another definition of the second. I think that the founders of the SI realised this issue when, in 1795, they decided that the metre as surveyed by Cassini IV was good enough for all purposes as long as it was 'supported' (at that time by Napoleon's government), and that it was part of a 'coherent' 'system'. The decision not to wait for the results of the survey of Delambre and Mechain reflected this view. We have lived quite comfortably � and successfully � with our slightly flawed definition of the metre since then. Condorcet's thought of the time, that the metric system was 'For all time, for all people' would need to be fundamentally revised if we want to start with a new second. Cheers, Pat Naughtin LCAMS Geelong, Australia on 2003-01-31 14.04, kilopascal at [EMAIL PROTECTED] wrote: > suggestion and inquiry: SI and ICAS2003-01-30 > > I don't understand the need to create new time units to parallel the second, > when we have the second, an SI unit. The problem with all of these ticks and > tocks is they are based on the variable earth day. > > Yes, it is possible, as you have shown below to give the ticks and the tocks > the same definition as the SI second. One can even define the foot and inch > by the same definition as the meter. > > The second and the SI prefixes are perfectly suitable for all measurements of > time. We don't need more complicated time units to deal with. Let's all > agree to scrap the whole idea. > > John > > > > > > ----- Original Message ----- > From: AAT at www.aatideas.org > To: U.S. Metric Association > Cc: [EMAIL PROTECTED] > Sent: Wednesday, 2003-01-29 12:49 > Subject: [USMA:24678] suggestion and inquiry: SI and ICAS > > > Madan, > > > Thank you for the suggestion about notation of years. The AAT is considering > ICAS revisions in light of comments and suggestions, and hopes to be able to > address these metrication concerns in future programming. > > > At the same time, other areas of development are also on the board. One is to > specify an IDC fixed unit that is fixed or derived from the SI second: > > > A method for defining a fixed tik unit based on the SI second is under > consideration. A tik may be designated as fixed from second (ffs) by the > following formula: By custom there are 86,400 seconds in a day, and there are > 100,000 tiks in a chron. A tik fixed from second (ffs) is thus 0.864 seconds, > and may be expressed as tt010 ffs. A chron that is fixed from second may be > likewise designated as t 1 ffs (equal to 86,400 seconds). > > "The second is the duration of 9 192 631 770 periods of the radiation > corresponding to the transition between the two hyperfine levels of the ground > state of the caesium 133 atom." (SI 2.1.1.3) From this a tik fixed from the > second would is derived from [9,192,631,770 x 0.864 = 7,942,433,849.3] > 7,942,433,849.3 periods of the radiation corresponding to the transition > between the two hyperfine levels of the ground state of the caesium 133 atom > per SI 2.1.1.3 (however calculation or application of measure is not > validated). Alternately one tok (tt100) ffs (8.64 s) would be 79,424,338,493 > periods per SI 2.1.1.3 (however calculation or application of measure is not > validated). > > However at this time the AAT ICAS department must inquire into the validity of > these derivations. > > > Sincerely,
