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From: mikes@AMES-NAS.ARPA
Newsgroups: net.physics
Subject: none
Message-ID: <718@sri-arpa.ARPA>
Date: Thu, 31-Oct-85 17:07:06 EST
Article-I.D.: sri-arpa.718
Posted: Thu Oct 31 17:07:06 1985
Date-Received: Mon, 4-Nov-85 02:14:44 EST
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From:  mikes@AMES-NAS.ARPA (Peter Mikes)

re: Quantum Reality
 I want to comment on the book: Quantum Reality by Nick Herbert (Doubleday 85)
  [ ISBN 0-385-18704-1 $19...] which covers in detail some topics touched 
  upon in past discussions of this group - such as EPR, Bells theorem, collapse
  of wave function and in general interpretation of the QM and its Measurement 
  Problem...
       Herbert describes three interpretations of the measurement in QM (p146)

 a) Copenhagen int - There is no 'deep reality'. This includes  original Bohrs
                      ' only the clics of the Geiger counters are 'real'..' and
                      Wheelers "Austin interpretation" of the 'observer created
                      reality' related to 'Delayed Choice exp' (pp164-166).
 b) All-Quantum int - based on Von Neumann's Grundlagen.. offers a unified
                      view, in which the QM is 'the deep reality' underlying
                      Classical phenomena just as Relativity offers deeper
                      explanation for e.g. Maxwell eq. and of Newtons laws..
c) Neorealist int -  which inherited all former 'hidden parameters theories'
                     and Stochastic Mechanics attempts starting with Fenyes
                     and includes Bohm's Quantum potential as a Pilot Wave.
                     This is the dissident view, which most people seem to
                     believe was killed by the experiment and Bells theorem.

I want - first of all - to recommend the book. If I recall correctly, I am so
far only one who confessed on net.physics to the heresy of neorealism and  so
by this 'endorsement' I want to say that the 'minority view' is fairly presentedin the book (while apparently not professed by the  author). 

A short biased comment on the merit of the three interpretations: All three
appear to have problems: c) requires FTL interactions which are unobserved. 
I want to stress: so far not observed directly. Compare that with ortho-
dox views a) and b) which are inherently non-local and so include "actions"
which are instant distant and un-observable. They may appear less offensive
as they seem to be more ghostlike, less real..
        - a collapsing psi? So what? What is psi anyway..

 Herbert treats well the issue of 'perturbation by measurement' as underlying
cause of quantum phenomena. This is a halftruth and cliche propagated by most
if not all textbooks. One of the results EPR achieved was to discredit that.
 If you are still captive of that essentialy classic paradigm read page 110:
 " Heisenberg principle follows from .. and has nothing to do with the 
   'unavoidable disturbance of the system by measurement'."

  Also valuable is discussion on pp150-152: Is it measurement (by conscious
  observer?) or is it just an natural process (of amplification?) which is
  responsible for 'collapses' and how to 'revive a dead Shrodinger cat' by
 performing a conjugate measurement. (This is the 'irreversibility connection'
 of the QM Measurement problem upon which we have touched lightly in the past).

   The book is written for a layman, assumes nothing, and so by necessity 
 contains (still another) non-mathematical exposure of QM. There are occasional
 weaknesses - e.g. on page 35 statement : " Planck's assumption (of E=n*h*f)
 was not justified by any physical reasoning.." is most unfair. However, the
 book goes further then other exposures in explaining Bell theorem and EPR
 arguments (BEPRA?) - which 
 
  as >I hope we all know< are the crucible from which the Phoenix of the new
 theory will arise...

                     and so provides an valuable contribution. Dont miss it.