From: tjroberts137@sbcglobal.net   
      
   On 7/31/17 7/31/17   9:10 AM, Jos Bergervoet wrote:   
   > On 7/31/2017 1:35 PM, Thomas Koenig wrote:   
   >> Time certainly doesn't equal length,   
   >   
   > Then height doesn't equal width. And you might just   
   > as well use the 'fathom' to measure the former and   
   > the 'furlong' for the latter.   
      
   Well said!   
      
   > More reasonable is to compute time^2-length^2 (the   
   > metric in our universe). Having the same units in   
   > that case saves you applying a conversion constant.   
      
   This would also avoid common confusion about "the speed of light" -- in MKS   
   that   
   conversion constant is not really the (vacuum) speed of light, but rather is   
   related to a symmetry of the metric. We conflate them by using the same symbol,   
   c, for both, because it "just so happens" that this constant is equal to the   
   vacuum speed of light.   
      
   Numerically these two meanings of "c" are the same [#]; physically they are   
   quite different. This has bewildered many a student....   
      
   	[#] Well, to current measurement accuracies.   
      
   Tom Roberts   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)