- #1
- 1,094
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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
--------------------------------------------------
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.
--------------------------------------------------
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%
--------------------------------------------------
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.
--------------------------------------------------
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)
--
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
--------------------------------------------------
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.
--------------------------------------------------
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%
--------------------------------------------------
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.
--------------------------------------------------
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)