Leggett inequalities and the completeness of quantum mechanics

TL;DR

This paper demonstrates that quantum mechanics cannot be completed with any form of realism, whether local or non-local, if we assume the arrow of time, as quantum predictions violate Leggett inequalities derived under these assumptions.

Contribution

It proves that assuming both realism (local or non-local) and arrow of time preservation leads to contradictions with quantum mechanics, violating Leggett inequalities.

Findings

Quantum mechanics violates Leggett inequalities under realism assumptions.

Realism plus arrow of time preservation is incompatible with quantum predictions.

The results are not invalidated by hidden variable theories like Bohm's.

Abstract

We consider the so called Legget inequalities which are deduced from the assumption of general (local or non-local) realism plus the arrow of time preservation. Then, instead of assuming cryto-nonlocal hidden variables, we assume any (local or non-local) realism compatible with the joint and non-joint expected values dictated by quantum mwechaanics. Hence, we prove that this double assumption is not consistent, since the corresponding general Leggett inequalities are violated by quantum mechanics. Thus, realism plus arrow of time preservation and quntum mechanics are not compatible. In other words, quantum mechanics cannot be completed with any (local or non-local) hidden variables, provide we assume the common sense of the arrow of time. The result would deserve to be experimentally tested and we discuss why it is not invalidated by hidden variable theories as the one from Bohm.