In 1964, Northern Irish physicist John Bell proved mathematically that certain quantum correlations, unlike all other correlations in the Universe, cannot arise from any local cause1. This theorem has become central to both metaphysics and quantum information science. But 50 years on, the experimental verifications of these quantum correlations still have ‘loopholes’, and scientists and philosophers still dispute exactly what the theorem states.
Bell’s theorem still reverberates
Nature 510, 467–469 (26 June 2014) http://dx.doi.org/10.1038/510467a