Tuesday, June 14, 2011

Denying reality and causality

A 2007 Nature paper announced:
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. ... 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.
The full paper is here and here. A 2001 Nature paper says similar things.

If these statements were true, then there would be Nobel Prizes given to those who established them. Textbooks would describe this as one of the great and profound discoveries of all time. And if these ideas really refuted three millennia of scientific thought, what replaced reality and causality?

The actual experiment is an attempt ot refute a non-local hidden-variable theory. It confirms quantum mechanics, as it has been understood for decades.

Non-local hidden-variable theory is much stranger than quantum mechanics. An experiment reject such a strange theory tells us nothing, and certainly does not justify the radical conclusions above. If there is something wrong with reality and causality, it is going to take some very convincing experiments.

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