[asa] Spooky Action At A Distance: Still Spooky

Floridi said:

> In my own contribution, I argued that, ultimately, genes are literally
> information (although a procedural kind of it) and that this interpretation
> allows one to unify, in a single approach to informational realism, both
> physics and biology. Basically, it makes a lot of sense to adopt a level of
> abstraction at which all processes, properties and entities, no matter
> whether just physical or also biological, are ultimately made of
> information.
>

We just had a scientific test for informational realism through the study of
what Einstein called "spooky action at a distance". First some background on
"spooky action at a distance" from Wikipedia:

> Current physical theories incorporate the upper limit on propagation of
> interaction as one of their basic building blocks, hence ruling out
> instantaneous action-at-a-distance. While a naïve interpretation of quantum
> mechanics <http://en.wikipedia.org/wiki/Quantum_mechanics> appears to
> imply the ability to send signals faster than the speed of light, careful
> reasoning about these cases shows that no *physical* signals are actually
> being sent. Einstein coined the term "spooky action at a distance" to
> describe these situations, which exhibit quantum entanglement<http://en.wikipedia.org/wiki/Quantum_entanglement>.
> Relativistic quantum field theory<http://en.wikipedia.org/wiki/Quantum_field_theory>requires interactions to propagate at speeds less than or equal to the speed
> of light, so quantum entanglement<http://en.wikipedia.org/wiki/Quantum_entanglement>cannot be used for faster-than-light-speed propagation of matter, energy, or
> information. However, it must be understood that a change to one entangled
> particle does indeed affect the other instantaneously, but this is only
> known after the experiment is performed and notes are compared, therefore
> there is no way to actually send *information* faster than the speed of
> light. Einstein could not believe this, and therefore he proposed, along
> with Boris Podolsky <http://en.wikipedia.org/wiki/Boris_Podolsky> and Nathan
> Rosen <http://en.wikipedia.org/wiki/Nathan_Rosen>, a thought experiment
> called the EPR paradox <http://en.wikipedia.org/wiki/EPR_paradox>. John
> Bell <http://en.wikipedia.org/wiki/John_Stewart_Bell> derived an
> inequality that showed a testable difference between the predictions of
> quantum mechanics and local hidden variables<http://en.wikipedia.org/wiki/Hidden_variables>theories.
> Experiments <http://en.wikipedia.org/wiki/Bell_test_experiments> testing
> Bell-type inequalities in situations analogous to EPR's thought experiments
> have been consistent with the predictions of quantum mechanics, giving
> strong evidence for nonlocality <http://en.wikipedia.org/wiki/Nonlocality>
> .
>
What Einstein believed is similar to Floridi above. The "information" is
real and therefore cannot travel faster than the speed of light. The EPR
paradox looked at locality, realism and counter factual definitiveness and
showed how it contradicted quantum theory, thus making
it "incomplete". Locality has been shown to be violated quite often by
Bell's inequality. Nevertheless, the realism above has been held onto quite
strongly by a number of scientists who thought non-locality alone was
sufficient to deal with quantum mechanics and they devised non-local
realistic theories. This idea has been blown out of the water today.
An experimental test of non-local realism
http://www.nature.com/nature/journal/v446/n7138/abs/nature05677.html

Most working scientists hold fast to the concept of 'realism'—a viewpoint
according to which an external reality exists independent of observation.
But quantum physics has shattered some of our cornerstone beliefs. According
to Bell's theorem, any theory that is based on the joint assumption of
realism and locality (meaning that local events cannot be affected by
actions in space-like separated regions) is at variance with certain quantum
predictions. Experiments with entangled pairs of particles have amply
confirmed these quantum predictions, thus rendering local realistic theories
untenable. Maintaining realism as a fundamental concept would therefore
necessitate the introduction of 'spooky' actions that defy locality. Here we
show by both theory and experiment that a broad and rather reasonable class
of such non-local realistic theories is incompatible with experimentally
observable quantum correlations. In the experiment, we measure previously
untested correlations between two entangled photons, and show that these
correlations violate an inequality proposed by Leggett for non-local
realistic theories. Our result suggests that giving up the concept of
locality is not sufficient to be consistent with quantum experiments, unless
certain intuitive features of realism are abandoned.

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Received on Wed Apr 18 18:11:45 2007