Re: Does the state-vector collapse?

From: David Blenkinsop (blenl@sk.sympatico.ca)
Date: Sat Sep 23 2000 - 09:29:10 MDT


Amara Graps wrote:

>
> . . . If one adopts
> a Bayesian approach to probability, then the Schroedinger wave
> equation simply becomes a posterior probability describing
> our incomplete information about the quantum system,
> rather than wave functions that collapse in reality upon our
> observation. It could clear up a lot of confusion.

Just a minute, hold on there! As part of your discussion, you yourself
mention the "amplitude squared" property of quantum waves, where the
wave just *has* to be considered as have a steadily "rotating" complex
vector amplitude. Now, it's my understanding that to get a normalized
probability distribution for the location of the associated electron, or
whatever, this really *does* involve squaring this complex amplitude, or
it involves squaring the sum total of any such vectors as may be
interfering in a given region of space. This is a situation quite unlike
anything in regular probability theory, something quite different added
in there, right?

Say you've got a single photon waveform, and say this wave is travelling
through two slits in a single photon, double slit experiment. The
probability of the photon hitting a screen is then a kind of
interference pattern of high and low probabilities as you move across
the screen. The waveform itself must then actually be a real, extended
structure of *some* kind, it seems to me, since it directly governs the
probability of finding the photon in the various bands of the
interference pattern.

Now, if the extended photon wave is actually real, then what happens to
most of it when the photon actually strikes the screen at one particular
spot? Does any momentum associated with the wave just suddenly vanish or
does it split off into another World, or what? These extended complex
amplitude structures have complicated shapes, and you need them for
predictions, so I'm not seeing how regular Bayesian probabilities would
explain them.

David Blenkinsop <blenl@sk.sympatico.ca>



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