From: tjroberts137@sbcglobal.net   
      
   On 1/21/18 1/21/18   3:55 AM, augustin.coppey@gmail.com wrote:   
   > I believe the uncertainty principle applies at ANY scale, and the quantum   
   > aspects are only limits of resolution, not the uncertainty principle itself.   
   > I find it bizarre and confusing to commingle the two issues.   
      
   You are confused, and make a fundamental error: confusing world   
   with model.   
      
   > If we look at the speed formula v = (x2-x1)/(t2-t1) as a transfer function   
   > with inputs and outputs (as in systems theory), we can see that the time   
   > series v(t) will always lag the time series x(t) by (t2-t1)/2 no matter what   
   > the scale or distance is.   
      
   That is a specific MODEL, and yes, this particular model has such   
   a lag. But in the world we inhabit, relative to a specified coordinate   
   system, any given object clearly has a definite velocity -- the   
   concept "lag" simply does not apply. (Measuring it is a different   
   question.)   
      
   Moreover, you got that particular model wrong. v is NOT (x2-x1)/(t2-t1),   
   but rather   
           v = lim(t1->t2) (x2-x1)/(t2-t1)   
   so the "lag" you worry about is infinitesimal, and thus negligible.   
      
   And, of course, one could use a different model which has no "lag"   
   at all, even for finite d:   
   	v(t) = lim(d->0) (x(t+d)-x(t-d)/(2 d)   
      
   > Example: even on a scale of meters and seconds, I cannot know precisely **by   
   > measurement** the speed and position of a slow moving object if I only have   
   > samples at each meter. I will know exactly the position when the object   
   > crosses the meter marker - but the calculated speed will be only an average   
   > speed between the last 2 markers, valid at the average location between the   
   > 2 markers. It is definitely NOT the speed when crossing the marker (simple   
   > proof: if the object is accelerating)   
      
   That is a limitation of your measurement system, not of the world   
   we inhabit.  That is, your INSTRUMENTATION has such a limit, not   
   the world. Better instruments have no such limit (but inherently   
   have other limits).   
      
   > So my question is: "why always discuss this measurement problem only in the   
   > context of quantum mechanics"?   
      
   There are indeed measurement issues related to all instruments,   
   outside of QM.  But in QM there are INHERENT issues that are unrelated   
   to instrumentation issues.   
      
   > It makes things more confusing than it needs to be.   
      
   No. There are issues specific to QM, that cannot be "simplified"   
   away. And also issues related to instrumentation, which are completely   
   different.   
      
   > Once it is clear that the uncertainty is a measurement principle true at any   
   > resolution,   
      
   But it ISN'T. Uncertainties in measurements do occur at all   
   resolutions, but they are resolution dependent -- better instruments   
   can reduce them. But QM puts fundamental limits on resolution for   
   some measurements, and no possible improvement in instrumentation   
   can reduce them.   
      
   > it becomes a lot easier to understand why there are limits of resolution at   
   > scales below the Planck constant.   
      
   The instrumentation issues you discuss provide no insight whatsoever   
   into the limits of QM.   
      
   Tom Roberts   
      
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