From: goldenfieldquaternions@gmail.com   
      
   On Tuesday, January 8, 2019 at 10:49:54 PM UTC-6, toadast...@gmail.com wrote:   
   > 04-JAN-2019   
   >   
   > Happy new year to all -   
   >   
   > Question:   
   >   
   > What physical status (within a given model) should be given   
   > to the property of "computability?"  For example, in the case   
   > of the information loss paradox, information clearly has   
   > a physical status, otherwise perfectly rational physicists   
   > wouldn't get so upset about losing it.   
   >   
   > So if the unitary evolution of a system -- in the form   
   > of unit probability as sum of all relevant systemic   
   > probabilities -- is, in principle, "computable," then   
   > what ponderable status should be ascribed to   
   > the notion of computability?   
   >   
   > Cheers,   
   > mj horn   
      
   Shannon, or really Shannon-Khinchin, entropy S = -k sum_n P(n)log[P(n)]   
   points to information as a physical quantity. This is carried further   
   with von Neumann entropy and quantum information. The transformations of   
   state quantum mechanically is unitary and it is not difficult to show   
   that entropy is constant. To the extent we consider these to be "quantum   
   computations" it would mean that anything computable is also observable.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)