Quantum Holism, EPR, and Bell’s Theorem

Posted on 20 January 2008

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Quantum entanglement is a revelation of the undivided wholeness of nature. We find quantum physics so mystifying largely because we typically presuppose that nature is merely the sum of its parts, and not an undivided whole.

When a physicist views nature through the lens of an experiment, the measurements isolate and reveal only fragments of nature (for example, selected properties of a particular electron). When the physicist attempts to integrate multiple measurements, it is found that they can not be coherently understood as representing separate entities. They can only be understood as aspects of a wholeness that is not revealed in any single measurement.

Einstein, Podolsky, and Rosen (EPR) published a famous paper in 1935 in which they argued that quantum theory can not be a complete description of physical reality. In this paper, they described a situation in which two particles interact and then move off in separate directions. After a long time traveling apart, the particles are located far away from each other. Then EPR make the assumption that, because the particles are so far apart, they can not immediately or instantaneously influence each other in any way, and therefore they must be considered separate and independent of each other. This implies that a measurement of the properties of one of the particles can not influence the results of a measurement of the properties of the other particle. Quantum theory, in contrast, describes the two particles as a single coherent system, regardless of their spatial separation. Moreover, because quantum theory describes the two particles as a single coherent system, it does not specify the properties of the particles as independent of each other. Their properties are mysteriously entangled with each other and neither one even has definite properties until a measurement is performed on one of them. For this reason, EPR concluded that the quantum description is not a complete description of the particles as independent entities.

Bohr responded to the EPR paper by challenging the assumption made by EPR that, because the particles are spatially separated, they are separate and independent. For many years it remained a philosophical issue because, at that time, there was not any known way to settle this question with an experiment. Several decades later, however, several experiments were done (e.g., by Alain Aspect) which demonstrated that Bohr was correct: The “locality” assumption made in the EPR argument is not true of the world. There is a mysterious nonlocal connection between particles, no matter how separate they may appear to be.

These experiments are closely connected to Bell’s Theorem, which can be stated (very simply) as follows: “If things are really separate, then there is a limit to how correlated they can be with each other.” The experiments that were done showed that things are correlated more that the limit in Bell’s theorem. Therefore, we use Bell’s Theorem to conclude that things can not really be separate.

Quantum physics, and the “measurement problem” in particular, is so enigmatic because we normally assume that the world is made up of separate pieces that together form a whole, rather than as a whole that can appear to have different pieces. So, when thinking about these quantum paradoxes, rather than asking how there can be these mysterious connections between separate particles, it may be helpful to ask instead how does the appearance of separation and decoherence emerge from fundamental abiding coherence.

“Decoherence” is a misnomer. Really, there is only coherence. The theory of so-called “de-coherence” is describing what might be called the emergence of the appearance of fragmentation. There is no real fragmentation or de-coherence going on. It is only an appearance. So, the whole manifests explicitly as apparent parts, but the parts are not really separate parts. They remain a whole. There is thus no real difference between explicit and implicit. All is coherent and whole, and never truly departs from that.

Perhaps the theory of decoherence has something to teach us about the teachings of mystics. It may provide a metaphor for how fundamental wholeness can appear as having distinct aspects while still remaining whole. This is a play of form and emptiness, difference and unity. It is seen in the dance of relationship, in the experience of the world, in life. It is symmetry. It is beauty.

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Posted in: Philosophy, Science