Bell's theorem allows local theories of quantum mechanics
Bell's theorem allows local theories of quantum mechanics
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贝尔定理允许量子力学的局域理论
DOI：
10.1038/s41567-022-01831-5
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发表时间：
2022
期刊：
影响因子：
19.6
通讯作者：
Hance J
中科院分区：
文献类型：
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作者：
Hance J
您的社论“基础调查”提出了一个有价值的观点，即现代科学和技术如此多地依赖于量子力学，试图了解其基础是值得花时间的 1。然而，我们认为有必要纠正社论中的一个不幸的错误，即这样的陈述：“解决这一悖论的一条途径可能是一个未被发现的、与构成相关行为的两个粒子相关的所谓隐藏变量。然而，约翰·斯图尔特·贝尔证明，这种方法无法解释量子力学任何使用隐变量的理论仍然需要非局域物理学。”这段话反映了一个常见的误解 2, 3，即贝尔定理证明再现量子力学的隐变量理论需要非局域物理学。事实上，量子力学的局部因果完成是可能的，如果它们违反了隐藏变量不以任何方式依赖于测量设置的假设。没有独立的证据表明这种假设（通常称为统计独立性）在量子系统中得到满足。因此，观察到的贝尔不等式的违反可以说表明，维持局部因果关系需要违反统计独立性。我们想强调，这不仅仅是一个解释问题。统计独立性假设对于贝尔型不等式 4-6 的表述在数学上是必要的。违反统计独立性的局部隐变量理论包括超决定论 7、逆因果论 8 和超测量 9 等理论。有些人以形而上学的理由驳回了它们，将违反统计独立性与“自由意志”或“自由选择”的存在联系起来，然后认为这些不是我们应该放弃的假设。事后看来，很难理解这种联系是如何产生的。我们认为它起源于这样的想法：隐藏变量和测量设置之间的相关性会以某种方式阻止实验者选择他们喜欢的设置。然而，这是错误地认为相关性与因果关系。任何关于自由意志的严肃哲学讨论都承认，无论如何，人类的能动性当然受到自然法则的限制。因此，统计独立性的数学假设与自由意志的哲学讨论无关。
Your Editorial ‘Survey the founda-tions’ makes the valuable point that with so much of modern science and technology dependent on quantum mechanics, trying to understand its foundations is time well spent 1. However, we see the need to correct an unfortunate mistake in the Editorial, which is the statement:“One route out of this paradox could be an undetected, so-called hidden variable associated with both particles that underlies the correlated behaviour. However, John Stewart Bell proved that such an approach cannot explain the quantum mechanical outcomes. Any theory that uses hidden variables still requires non-local physics.” This passage reflects a common misconception 2, 3 that Bell’s theorem proves that hidden variable theories reproducing quantum mechanics require non-local physics. In fact, locally causal completions of quantum mechanics are possible, if they violate the assumption that the hidden variables do not in any way depend on measurement settings. There is no independent evidence that this assumption—commonly known as statistical independence—is fulfilled for quantum systems. As a consequence, the observed violations of Bell’s inequality can be said to show that maintaining local causality requires violating statistical independence. We wish to stress that this is not merely an issue of interpretation. The statistical independence assumption is mathematically necessary for the formulation of Bell-type inequalities 4–6. Types of local hidden variables theories that violate statistical independence include those that are superdeterministic 7, retrocausal 8 and supermeasured 9. Some have dismissed them on metaphysical grounds, by associating a violation of statistical independence with the existence of ‘free will’or ‘free choice’and then arguing that these are not assumptions we should give up.It is, in hindsight, difficult to understand how this association came about. We believe it originated in the idea that a correlation between the hidden variables and the measurement setting would somehow prevent the experimentalist from choosing the setting to their liking. However, this is mistaking a correlation with a causation. And any serious philosophical discussion of free will acknowledges that human agency is of course constrained by the laws of nature anyway. For this reason, the mathematical assumption of statistical independence bears no relevance to the philosophical discussion of free will.