#### Hans de Vries

Science Advisor

Gold Member

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EPR experiments seem to show a significantly higher

correlation rate in the detection of separated photons which

are in an entangled state. From the measured correlation we

may or may not want to draw very fundamental conclusions.

One such a far reaching conclusion would be that our world

is fundamentally non-local and that "action on a distance"

is possible. This would be in serious friction with the Special

Theory of Relativity.

Rather then saying that QM predicts non-locality we need to

be more specific and state that the correlations measured

predict non-locality, that is, if all other alternative local

explanations are exhausted.

The most successful Quantum Field Theory, The Standard Model

which unifies the Electromagnetic, Weak and Strong forces does

not need "action on a distance". Path integrals do not "jump

space" and respect Special Relativity.

Some of the champions of the Standard Model have a strong

preference for local theories. For instance Gerard ‘t Hooft:

http://www.phys.uu.nl/~thooft/quantloss/sld020.htm

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I would like to show an example of how a purely local

interpretation can give a much higher correlation equal

to the results of the Aspect and Innsbruck experiments

without the need for action on a distance.

I will discuss first the “Bell Inequality” case, the non-local

QM case and then the local alternative. I’ll use an example

based on the Wollaston Prism which is used in most if not

all EPR experiments.

The Wollaston Prism splits a light beam in two beams, one

horizontally and one vertically polarized. A single photon

is said to exit at either the horizontal or vertical output, but

never at both.

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We will look at the case where the two entangled photons at

A and B are both polarized at 45 degrees with respect to the

Wollaston prisms:

The Bell inequality case: It is presumed that the photon at

A has a 50:50 % chance to exit at the horizontal or vertical

output and the same is true for the photon at B. However,

the outcome at A and B are presumed to be completely

independent even though the particles are entangled.

The correlation is calculated to be 50%

The non-local QM case: It is presumed that the photon at

A has a 50:50 % chance to exit at the horizontal or vertical

output. However when it exits at for instance the vertical

output then “action on a distance” causes the photon at B to

be also vertically polarized as a result of the measurement at A.

The correlation is assumed to be ~100%

The alternative local model: We presume that both photons

share a property because they are entangled. They are more

equal then other seemingly equal photons. If the photon at

A leaves at the horizontal output then B will generally also leave

at the horizontal output because they share this property.

Although different photons will exit at different sides, entangled

photons will typically leave at the same side resulting in a

correlation of ~100%

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This would mean that the selection process at the Wollaston

Prism is not entirely random anymore but became predeter-

mined by the property at the place where the photons became

entangled.

This then requires a property to be explained. One possibility

I came across stems from the fact that fundamental photons

(spin 1 bosons) are either left or right circular polarized.

So called linear polarized single photons as presumed in the

EPR experiments can not be fundamental since they would

have spin 0.

Linear polarized photons must be considered to be a combination

of a photon with spin up and a photon with spin down. This now

introduces extra degrees of freedom. These degrees of freedom

may be random for arbitrary photons but equal for entangled

photons coming from a PDC.

The particular constitution of the up and down photon may make

the difference in the birefringent beam splitter where a choice

is forced for the 45% polarized combination to exit at either the

horizontal or vertical polarized output.

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This example just goes to show that one should exhaust

all possible local explanations before such far reaching

conclusions as non-locality can be made with certainty.

It’s my opinion that the above alternative should be

disproved convincingly in order to prove non-locality.

Regards, Hans

PS. The difference in correlation in the actual Aspect and

Insbruck experiments is not as high as here stated because

several things are going on at the same time. The photons

are assumed to be superposition states and various different

angles are used randomly (0, 22.5 45 and 67.5 degrees)