QM, Bell's Inequality and Quantum Cryptosystems

[Mike Rosing]

On Thu, 2 Jan 2003, Anonymous wrote:

> No. Bell's inequality tells us that there are no "hidden variables".
>It's not that we don't know the value of the measureable prior to
>wavefunction collapse...the specific measureable doesn't exist prior to
>wavefunction collapse. When Bell formulated the testable inequality circa
>1980, and then it was experimentally violated (the inequality, that is,
>not the theory behind it), it became accepted within physics that (as
>expected) wavefunction collapse determines (right then and there) the
>value of observables, forcing the universe to choose, according to the
>probabilities. (Of course, this was basically understood from QM's
>beginnings, but prior to John Bell's work we couldn't actually test that
>this was reality.)

This really gets into my interpretation.  I don't need hidden
variables.  The crux to me is that the particles are correlated
and we use math to describe the probability of what the correlation is.
Once we measure one particle we know the other one.  Before we measure
we don't know anything.  That's all.  QM tells us what the probability
distribution is for any given measurement, it can't tell us anything
about a particular outcome.

> Taking a measurement (whether acidentally or on purpose) forces the
>quantum system to "choose" instantaneously. Einstein understood this
>aspect of Quantum Mechanics so well that he and 'P' and 'R' concocted the
>EPR gedanken to show that this implies what is effectively "action at a
>distance"...the different pieces of a quantum system, even far removed,
>spontaneously 'know' about the other parts. (In fact, I would bet that
>Einstein's original complaints about QM's action-at-a-distance may have
>been what prompted the reactionary fad of 'well, QM is merely a useful
>calculational tool...)

In my model there is no instantaneous choice.  It was chosen at
the start.  We can not know anything about the correlation until
we measure, then we know everything.

> But in the end, as strange and unreasonable as this
>action-at-a-distance may be, it's now regularly seen in the laboratory.
>(Even wierder are the 'quantum eraser' and other bizarre behaviors).

Yeah, Scientific American has some really nice "popular" descriptions
of these things.  It just doesn't seem weird to me.  It seems like
reality.  :-)

Patience, persistence, truth,
Dr. mike