Quantum entanglement, fair sampling, and reality: Is the moon there when nobody looks?

Abstract

In 1981 Mermin described a clever and simplified version of Bell’s theorem. He pointed out in a straightforward way that interpreting entanglement from a local realist point of view could be problematic. I propose an extended version of Mermin’s device that can be given a simple local realist interpretation by a sample selection bias. I argue that we still have no scientific reason to believe that the moon could not be there when nobody looks.