Stephen, There is one *and only one* "system of units" (SI) which has properties of (a) uniqueness(only one unit for each quantity), (b) coherence(no numerical coefficients relating units other than the number one), and (c) completeness(a defined coherent unit for every quantity of interest).
The sets of units called "imperial", inch/pound, Customary, cgs, esu, emu, etc., etc. do not meet the requirements of a "system" of units. Only SI is a "system" of units. Gene. ---- Original message ---- >Date: Fri, 5 Mar 2010 10:16:03 +0000 >From: Stephen Humphreys <[email protected]> >Subject: [USMA:46834] RE: Replacement of metric signs on I-19 (Arizona) >deferred >To: "U.S. Metric Association" <[email protected]> > > Let me come back on that one with some brief > answers: > > 1) "Hundreds of systems" - We know that in reality > and in practice there are 2 systems known/used > internationally. That's just 2. >...
