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AGPhil: Arbeitsgruppe Philosophie der Physik

AGPhil 10: Foundations of Quantum Mechanics II

AGPhil 10.4: Talk

Thursday, March 13, 2025, 18:30–19:00, HS XVII

More on a Presupposition of Bell's Theorem — •Carsten Held — Nonnenrain 2, 99096 Erfurt, Germany

In earlier work, the Bell-CHSH inequality was shown to rest on a non-trivial presupposition, i.e., that the values of elementary spin quantities are scalars, not, e.g., vectors. The theorem's argument succeeds for scalars and fails for vectors. However, the reference to vector values can be motivated from the physics of spin. Hence, it seems that the Bell-CHSH inequality fails as a proof of non-locality. But how powerful is this argument really? We discuss two objections: (A) If we introduce four unit vector values, we learn that they cannot be mapped consistently onto QM observables. (B) Given the four vector values, the contradiction vanishes but we can map them 1:1 to scalar values and for them the contradiction reappears. If we analyze these objections, we find that neither is convincing.

Keywords: Bell’s theorem, Bell-CHSH inequality, locality