Topic summary
Bell inequalities
Extracted from the Wikipedia article Bell's theorem.
The first laboratory experiment to observe a Bell inequality violation was conducted by John Clauser and Stuart Freedman, who published their results in 1970. More advanced experiments, known collectively as Bell tests, have been performed many times since. Often, these experiments have had the goal of "closing loopholes", that is, ameliorating problems of experimental design or set-up that could in principle affect the validity of the findings of earlier Bell tests. Bell tests have consistently found that physical systems obey quantum mechanics and violate Bell inequalities; which is to say that the results of these experiments are incompatible with local hidden-variable theories.