Sunday, April 22, 2007

QM Says Goodbye to Reality?

This was the "big" news of the week in physics. A paper by the Zeilinger's group in Austria has made a test that rules out large classes of "realism" model that could not be saved even when locality is relaxed. The test of the Leggett's inequality, which is an extension of the Bell inequality, has made QM even more verified than before.

This is a rather interesting paper because, till now, the Bell-type experiments can only violate "local realism", but are not able to distinguish if they violate either "locality", "realism", or both. Locality is the interconnectedness of entangled properties no matter how far they are in space. A measurement on one instantaneously affects the other. Realism is an idea that a system actually have definite properties moving with it locally even when we haven't measured it. The latter is what makes this purely quantum mechanical and the basis of Schrodinger's infamous cat thought experiment.

The more they test it, the more convincing it becomes....


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