EPR Paradox, Quantum Nonlocality and Physical Reality

Abstract: Eighty years ago Einstein demonstrated that a particular interpretation of the reduction of wave function led to a paradox and that this paradox disappeared if statistical interpretation of quantum mechanics was adopted. According to the statistical interpretation a wave function describes only an ensemble of identically prepared physical systems. Searching for an intuitive explanation of long range correlations between outcomes of distant measurements, performed on pairs of physical systems prepared in a spin singlet state, John Bell analysed local realistic hidden variable models and proved that correlations consistent with these models satisfy Bell inequalities which are violated by some predictions of quantum mechanics. Several different local models were constructed, various inequalities proven and shown to be violated by experimental data. Some physicists concluded that Nature is definitely not local. We strongly disagree with this conclusion and we critically analyze some influential finite sample proofs of various inequalities and so called quantum Randi challenges. We also show how one can win so called Bell game.The violation of inequalities does not prove that local and causal explanation of correlations is impossible. The violation of inequalities gives only a strong argument against counterfactual definiteness and against a point of view according to which experimental outcomes are produced in irreducible random way. We also explain the meaning of sample homogeneity loophole and show how it can invalidate statistical significance tests. We point out that this loophole was not closed in several recent experiments testing local realism.