NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/sci/physics/12071

Internet Message Format | 1992-07-30 | 3.6 KB

Path: sparky!uunet!stanford.edu!rutgers!dziuxsolim.rutgers.edu!ruhets.rutgers.edu!bweiner
From: [e-mail] (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Bell dethroned
Message-ID: <[e-mail]>
Date: 30 Jul 92 21:51:22 GMT
References: <[e-mail]> <[e-mail]> <[e-mail]>
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 68

Douglas Danforth writes ("]" comments are me, Ben Weiner):
|The model does not use variable efficiency.  Each detector has a
|fixed efficiency equal to 81.8%.
|
|]                               you can make the results do whatever
|]you want.  Why should the detectors be variably efficient?  Shouldn't
|]this happen with any old photons, not just correlated photons?
|
|Yes.
|
|]Shouldn't, then, one be able to test this by putting a detector in
|]front of a known source, and just rotating the damn detector?
|
|Test what.  The Crown model predicts that rotating a single detector
|does not change the counts observed at that detector.
|]
|]How can anyone possibly presume to DERIVE the efficiency of a
|]detector?
|
|Because the model specifies a specific pattern of response in
|the hidden variable space.  The effeciency "derived" is the maximum
|efficiency allowed by the model that will still give the quantum results...
|
|]           Do you suppose Aspect's detectors magically had the same
|]efficiency as, much earlier, Clauser's?
|
|No.  There is a range of efficiencies possible that still admit
|realistic local theories for this two particle correlation experiment.
|...
|There is no conspiracy in the crown model.

OK, I think I understand a little better.  The detectors'
efficiency varies under rotations in hidden variable space, that is,
there is some mystery variable which is, presumably, correlated
between the two photons (or spin 1/2 particles, please note!) and
which causes detector efficiency to vary.  It's not a physical
rotation.  One can cut down the detector efficiency overall and
the statistics supposedly don't change, so your cited efficiency
(81.8%) is actually a maximum.  It seems to me that in your model
_no_ detector could ever possibly be more efficient than that,
because the hidden mechanism that prevents detection would always
operate.

I repeat:
1.  There is no known mechanism to cause such detector inefficiency.
    Not a terribly strong point - although it seems to me that any
    detector which detected more than 81.8% of any incident photons
    would be a counterexample.  I would not be surprised to hear of
    a CCD which exceeds this.
2.  It is surprising that the "hiding mechanism" would work the
    same way for photons and spin-1/2 particles.
3.  Strongest point: This argument, in which the "missing" photons
    are the ones which could make the difference in the test of QM
    predictions, has been recognized before.  Most people just do
    not believe it; one argument is that since QM predicts stronger
    correlations than a classical model, it would be strange if those
    photons which were missing were precisely those which brought down
    the correlation.  You may not be persuaded by this.  I continue
    to regard a mysterious relation between the direction of some
    hidden variable and the efficiency of detection as a
    conspiratorial effect.

Please, go right ahead and publish.  Better you should argue with
referees than with graduate students.  I do recommend that you read
Mermin's papers, because they are surprising in the depth of their
conclusions, especially given their simplicity.

Ben Weiner