2014/10/09 by Marek Żukowski, Marek Zukowski, Časlav Brukner +1 · 2 citations
Computer Science · Physics and Astronomy · #Quantum Information and Cryptography #Quantum Mechanics and Applications #Relativity and Gravitational Theory #physics.hist-ph #quant-ph
paper · pdf · doi:10.1088/1751-8113/47/42/424009
published as M. Zukowski and C. Brukner, J. Phys. A: Math. Theor. {\bf47}, 424009 (2014) · approximately the published version
openalex publication_date 2014/10/09 · arxiv created 2015/01/19 · arxiv updated 2015/01/20 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Bell's theorem is 50 years old. Still there is a controversy about its implications. Much of it has its roots in confusion regarding the premises from which the theorem can be derived. Some claim that a derivation of Bell's inequalities requires just locality assumption, and nothing more. Violations of the inequalities are then interpreted as ``nonlocality'' or ``quantum nonlocality''. We show that such claims are unfounded and that every derivation of Bell's inequalities requires a premise -- in addition to locality and freedom of choice -- which is either assumed tacitly, or unconsciously, or is embedded in a single compound condition (like Bell's ``local causality''). The premise is equivalent to the assumption of existence of additional variables which do not appear in the quantum formalism (in form of determinism, or joint probability for outcomes of all conceivable measurements, or ``additional causes`'', or ``hidden variables'', ``complete description of the state'' or counterfactual definiteness, etc.). A certain irony is that perhaps the main message of violation of Bell's inequalities is that our notion of locality should be based on an operationally well-defined no-signalling condition, rather than on local causality.