Jerry, As has already been noted here, only one *system* of units, the SI, exists in the world, which meets all three minimum requirements for recognition as a "system" of units of measurement. Allow me to explain in more detail.
Requirements for a "system" of units are: 1. Uniqueness- There is one and only one coherent unit of measurement for each quantity in the system. 2. Coherence- Every unit relates to the other units in the system without numerical factors other than one (1). Factors such as 12, 3, 5280, etc. are never used to relate the units of the system. The more exacting definition of coherent units relates the coherent units with the equations for their corresponding quantities. See NIST SP 330. 3. Completeness- A coherent unit is defined for every quantity of interest is science or technology. Gene. ---- Original message ---- >Date: Sun, 1 Feb 2009 09:40:44 -0800 (PST) >From: Jeremiah MacGregor <[email protected]> >Subject: [USMA:42771] Re: Small item seen on TV >To: "U.S. Metric Association" <[email protected]> >... > I'm learning more about the situation from this > forum and I see things differently then before. I > see where the use of multiple systems creates a > mess...
