Paper detail

Bell's Theorem and the Causal Arrow of Time

Einstein held that the formalism of Quantum Mechanics (QM) entails "spooky actions at a distance". Indeed, in the 60's Bell showed that the predictions of QM disagree with the results of any locally causal description. Accepting non-local descriptions while retaining causality leads to a clash with the theory of relativity. Furthermore, the causal arrow of time by definition contradicts time-reversal symmetry. For these reasons, some authors (Feynman and Wheeler, Costa de Beauregard, Cramer, Price) have advocated abandoning microscopic causality. In the present article, a simplistic but concrete example of following this line of thought is presented, in the form of a retro-causal toy-model which is stochastic and which provides an appealing description of the specific quantum correlations discussed by Bell. One concludes that Einstein's "spooky actions" may occur "in the past" rather than "at a distance", resolving the tension between QM and relativity, and opening unexplored possibilities for future reformulations of QM.