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From: djo@pbhyc.UUCP
Newsgroups: sci.philosophy.tech
Subject: Re: Aspect Experiment and Meaning of QM
Message-ID: <652@pbhyc.UUCP>
Date: Tue, 26-May-87 16:47:57 EDT
Article-I.D.: pbhyc.652
Posted: Tue May 26 16:47:57 1987
Date-Received: Wed, 27-May-87 05:07:11 EDT
References: <1275@cci632.UUCP> <766@klipper.cs.vu.nl> <650@pbhyc.UUCP> <1828@sphinx.uchicago.edu>
Reply-To: djo@pbhyc.UUCP (Dan'l Oakes)
Organization: Pacific * Bell, San Ramon, CA
Lines: 25
Keywords: aspect light faster

In article <1828@sphinx.uchicago.edu> ogil@sphinx.UUCP (Lord Julius) writes:
>Now put two detectors in the holes, so you know which hole the photon went
>through on its way to the detector.  Now the probability that the original
>detector detects the photon is _independent of its position_!  Yes, just
>placing those two detectors in the holes changed the results, demonstrating
>that the universe does conform to the state of man's knowledge, at least
>in one sense.
>
>To make things even worse, if the two detectors in the holes are unreliable --
>they don't always detect a photon -- the interference pattern is a combination
>of the original, no detectors pattern and the unvarying, perfectly reliable 
>detectors pattern.  This one never fails to amaze and confuse me.  It just
>goes to demonstrate that our normal intuition is quite often (perhaps mostly)
>wrong when it comes to the realm of subatomic physics. 

Forgive me for stating the obvious, but I do believe that a modified version
of Heisenberg's Principle is applicable here -- it is not our knowledge of
"which hole the photon went through," but the presence and activity of the
detectors themselves -- and no bull about "passive detectors," please; there's
no such thing when dealing with a photon-sized mass -- which changes the
behavior of the photons as observed by the "original" detector.

And I second the nomination of Feynman's excellent book.

Dan'l Danehy-Oakes