Bell's theorem: why probability factorisation fails

Abstract

The empirical proof of Bell inequality violations was a landmark moment for research into quantum foundations. It commits us to a universe without strict relativistic locality or requires that we escape through a potential loophole like many-worlds or superdeterminism. In this work, we consider a sequential, single-spin experiment whose auto-correlations match the two-spin entangled correlations of a Bell scenario. We use a counterfactual equivalence between the two to argue that Bell-type correlations are actually just a different implementation of the sequential experiment. This comports well with the counterfactual basis of the original EPR argument, and explains any apparent non-locality as a consequence of indirectly measuring quantities that do not have predefined values, due to the state-altering nature of sequential spin measurements.