Seventy Years of the EPR Paradox

Abstract

In spite of the fact that statistical predictions of quantum theory (QT) can only be tested if large amount of data is available a claim has been made that QT provides the most complete description of an individual physical system. Einstein's opposition to this claim and the paradox he presented in the article written together with Podolsky and Rosen in 1935 inspired generations of physicists in their quest for better understanding of QT. Seventy years after EPR article it is clear that without deep understanding of the character and limitations of QT one may not hope to find a meaningful unified theory of all physical interactions, manipulate qubits or construct a quantum computer. In this paper we present shortly the EPR paper and the discussion which followed it. By emphasizing the difference between quantum phenomena and hypothetical invisible sub phenomena we show that paradoxes are only found if incorrect models of sub phenomena are used. The violation of Bell and CHSH inequalities demonstrate clearly that "an entangled pair of photons" resembles neither "a pair of Bertlmann's socks" nor "a pair of fair and random dices". Finally we rephrase the EPR question by asking whether QT provides the complete description of experimental data.