Nonlocality without counterfactual reasoning

Abstract

Non-local correlations are usually understood through the outcomes of alternative measurements (on two or more parts of a system) that cannot altogether actually be carried out in an experiment. Indeed, a joint input/output -- e.g., measurement-setting/outcome -- behavior is non-local if and only if the outputs for all possible inputs cannot coexist consistently. It has been argued that this counterfactual view is how Bell's inequalities and their violations are to be seen. We propose an alternative perspective which refrains from setting into relation the results of mutually exclusive measurements, but that is based solely on data actually available. Our approach uses algorithmic complexity instead of probability, implies non-locality to have similar consequences as in the probabilistic view, and is conceptually simpler yet at the same time more general than the latter.