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From: AI.Mayank@MCC.ARPA
Newsgroups: net.physics
Subject: Re: Faster than Light
Message-ID: <353@sri-arpa.ARPA>
Date: Wed, 3-Jul-85 17:59:09 EDT
Article-I.D.: sri-arpa.353
Posted: Wed Jul  3 17:59:09 1985
Date-Received: Thu, 11-Jul-85 20:10:00 EDT
Lines: 44

From:  Mayank Prakash 


>The wave function is not physical matter or an energy field.  It is a
>computational entity used to predict the results of experiments.  When you
>solve the equations of motion, you are solving for the motion of a computational
>entity which can then be used to predict the results of experiment.  It won't
>predict results that are in violation with relativity, ie that the photon
>gets absorbed sooner than the speed of light would allow for.
>
>The wave function itself is just a computational device and is not some real
>physical thing that is distributed over space.  The wave function "collapse"
>is simply the statement that there was one photon and if it gets absorbed in
>a given detector then no other detectors will absorb it.  This is about as
>simple and intuitive as you can get.
The wave function is more than just a computational device - it is the actual
probability amplitude, whose mod-squared gives the probability density of
seeing a photon at a given point. The wave function collapse is the stronger
statement that the probability amplitude, which was spread out over a
(possibly) large region of space, is now localized within a small volume in
which the photon was seen. Before the observation was made, the probability
distribution was ACTUALLY spread out, and after the photon is detected at some
point, it "collapses" to within that volume. So there is a change in the ACTUAL
porbability density of seeing that photon at other spots in space once it has
been detected at earth.

Note that you are confusing two issues here - the photon does not get absorbed
sooner that the speed of light would allow for because the wave function does
not expand faster than the speed of light, thereby ensuring that the
PROBABILITY of its being seen is zero before that time, but once that time has
elapsed, and an observation made, it collapses "instanteneously." That is the
only way contradictions can be avoided. The situation with regards to
relativity is tolerable (not completely satisfactory) only because this will
lead to no observable contradictions as long as the wave function (i.e., the
actual probability distribution, not just a mathematical entity) collapses
instantaneously.

- mayank

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II  Mayank Prakash  AI.Mayank@MCC.ARPA      (512) 834-3441		II
II  9430 Research Blvd., Echelon 1, Austin, TX 78759.			II
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