EPR paradox

The EPR paradox, or Einstein-Podolski-Rosen paradox, was at the origin of a thought experiment proposed by Einstein and his team in 1935 to violate the Heisenberg position-momentum inequalities and to show that the probabilistic interpretation of quantum mechanics could only be effective.

The use of probabilities was a provisional expedient reflecting the absence of complete knowledge about the values of certain parameters determining the individual behaviour of particles, like the kinetic theory of gases with the Maxwell distribution. Repeated in a different form relative to photon spin by David Bohm, this experiment was carried out later by Alain Aspect in 1982. In the meantime the Irish theoretician John Bell had demonstrated his famous inequalities showing that Einstein and the founders of quantum mechanics were right.

Aspect's results, and those of others, have always confirmed the standard interpretation of quantum mechanics, furthermore showing that the notion of non-locality is a central element in quantum mechanics.