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From: mikes@AMES-NAS.ARPA
Newsgroups: net.physics
Subject: Re: Heisenberg Uncertainty Principle
Message-ID: <492@sri-arpa.ARPA>
Date: Mon, 12-Aug-85 17:18:21 EDT
Article-I.D.: sri-arpa.492
Posted: Mon Aug 12 17:18:21 1985
Date-Received: Sat, 17-Aug-85 06:03:43 EDT
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From:  mikes@AMES-NAS.ARPA (Peter Mikes)

	Subject: Re: Heisenberg Uncertainty Principle
	            In-Reply-To: Article(s) <3506@decwrl.UUCP>
	
  > Is it strictly a case of the measurement process itself disturbing the
  > individual particle, or is something else going on there? Can we
  > find a measurement process that uses small enough particles so that they
  > won't disturb the particles we are trying to measure?
	
	But you can't!
	           gwyn@brl-tgr.ARPA (Doug Gwyn )

  I would like to prefix my comment to the above by few disclaimers: 
       1) the opinions are mine, not my employers, his clients etc etc
       2) my opinions on QM are unorthodox - but I hope not in conflict with
          known facts (or even future one's)
       3) I agree, in this case (and others) with Gwyn : "You cant" in both
          accepted and other interpretations of the Quantum Noise, BUT
 I think that the fact that "there is no measurement process possible" which
 would determine p&q DOES NOT (necessarily) implies that 'it is strictly a
 measurement process itself, disturbing the particles..' . Actually I believe
 that Heisenberg analysis of different measurement setups is secondary  and
 accidental. There is something called the "fluctuations of the vacuum' which
 has nothing to do with measurement process. There is an 'intristic pressure'
 of the electron gas, which can be measured (as high pressure limit of conven-
 tional materials) and which can be calculated from the Uncertainity Principle.
 There is no measurement involved! This 'quantum pressure' is as real as an
 osmotic pressure in gas is real - neither is dependent on what WE know about
 the system. Once you accept the 'existence' of this disturbance, the Uncertain- ty Principle follows naturally as a special case. I consider the typical
 textbook presentation of Heisenbergs Principle AS CAUSE of the quantum rand-
 mness as a half-truth which cannot survive a critical analysis.
In other words 'even if you could determine p&q at the same time ( some believe
 that that is a meanigless statement) I believe that you would not be able to
 make exact predictions - just knowing the MACROSCOPIC potential and those 
 exact initial conditions.'  We all agree, I think, that 
 
	 Gwyn:"This is a matter of fundamental principle, not of
	insufficient cleverness on the part of the measurer."
 ...that you cannot measure both p&q.

  The difference of opinion is subtle and easy to be overlooked. The key, once
 again is the Einstein's definition of what is ' a complete description of
 reality'.  Later developments (Bell's uneqality and Aspects experiments) 
 did not invalidated his remarkably logical definition, they just confirmed
 that it is indeed a fundamental principle that 'you cant' discover 'hidden
 parameters' which a clever experimenter can go after to circumvent Heisen-
 bergs principle.
      Accepting both Einstein's definition and Bell's analysis, it seems to
 me that 1) there is both p and q - 2) There is no way we can determine both.
 That in itself may be disturbing (that are things which WE cannot know) but
 it's not impossible (actually - it rather natural).
 
    The real issue - which I hope somebody will respond to is this: Bells ana-
 lysis killed the 'Hidden Parameter Theories'. OK - do the concepts of the 
 'field' (these are related but non-identical concepts: Bohm's/Fenyes's 
 Quantum potential, DeBroglies Pilot Wave, and this concept of the Quantum
 Fluctuations, taken outside of the context of QED) which is influencing 
 the  microscopic particle, which is moving according to the Schrodingers eq.
 qualify as Hidden Parameters? I do not see how - and I am eager to learn.
	                                                    
         
                                              Peter M.