From: James R. Frysinger <[EMAIL PROTECTED]> wrote: <<[1] Using the megagram (and its symbol Mg) instead of the metric ton or tonne is a *very* bad idea....>>
<Excellent point on the propensity of neophytes to the use of the metric system to confuse things. Proof in point, my liberal arts college students sometimes confuse milli and micro and occasionally mega prefixes.> I can relate to that. Last night I had a similar momentary confusion between microfarads and picofarads while looking through two electronic parts catalogs for a capacitor (one used uF and the other usef pF). <Judging from the rate at which the CGPM is willing to make changes (they favor reluctance over rashness), my personal guess is that it would take over 10 years to get them to change the name of the kilogram, and more likely it would be forty of fifty years. I don't want to wait that long to see the U.S. go metric.> Me either. After the new Senate and Congress are seated, I'll ping my legislators about the much-needed FPLA reform. <<[3] Trying to retire the hectare and liter would be very foolish.....>> <Your points on this are excellent! This is meant to be a useful system, albeit one with a rigorous theoretical basis. But, rigor aside, it must be useful to the public.> Thank you. I view these units the same way I view the 24 hour clock--not ideal, but too ingrained and too useful to ditch. <I disagree here only to the extent that I think the analogs will be felt to be cm:in, dm:ft, m:yd. The decimeter is too large to be considered the replacement for the inch, in my view. And my students are more likely to confuse inches with centimeters than with decimeters when they must use dual labeled meter sticks or tapes.> You just made my point for me. :-) The decimeter can't be confused with the inch. I'm advocating awareness of all three sub-meter units (mm, cm, and dm). I've found the dm useful when measuring large things like the side of a shed, because I can stand well back and easily count them on the tape. Then I get closer to count the cm and mm. The dm also seems to be psychologically more palatable to Americans because the numbers of them are smaller (12" is about 3 dm rather than about 30 cm). <True enough! In public, it should be "the metric system" first and foremost, then *perhaps* and parenthetically "the SI". In legal documents, the introduction should always define "the metric system" as used within as meaning "the SI". That's essential for legal and technical reasons and since darned few Americans read legal documents, it won't get in their way.> Yes, I didn't mean we should suppress the name "SI." Even for materials aimed at laypeople, it would be perfectly fine to include "SI" in subtitles. <Thanks for this breath of common sense, Jason! This is one of the most intelligent posting I've seen here for weeks. Some people get college degrees and some get an education. Relatively few get both, a wag might say.> Heh! Thank you for the boost. I was inspired to write the post while I was reading threads on the sci.space.* USENET newsgroups. People were arguing over the best reusable launch vehicle to drastically lower launch costs to the point where routine manned spaceflight and space tourism would be practical. They completely missed the point that this depends solely on the cost per kilogram of payload to orbit. The cheapest way to achieve this is with simple, mass-produced Minimum Cost Design (MCD) expendable rockets using "boilerplate" tanks and simple pintle-injector rocket engines. They're not nearly as glamorous as reusable winged spaceships, but they'll get the job done, as does the current metric system. -- Jason
