反事实确定性

在量子力学中，反事实确定性（，简称CFD）是指“有意义地”谈论尚未进行的测量的结果的确定性的能力（即假设物体的存在和物体的属性的能力，即使它们尚未被测量）。术语“反事实确定性”被用于物理计算的讨论，尤其是与量子纠缠现象以及贝尔不等式相关的讨论。Enrique J. Galvez, "Undergraduate Laboratories Using Correlated Photons: Experiments on the Fundamentals of Quantum Mechanics," p. 2ff., says, "Bell formulated a set of inequalities, now known as 'Bell’s inequalities,' that would test non-locality. Should an experiment verify these inequalities, then nature would be demonstrated to be local and quantum mechanics incorrect. Conversely, a measurement of a violation of the inequalities would vindicate quantum mechanics’ non-local properties."在此类讨论中，“有意义地”意味着能够在统计计算中将这些未测量的结果与已测量的结果同等对待。反事实确定性是与物理系统的物理和数学模型直接相关的一个（有时是假设但未说明的）方面，而不是关于未测量结果的含义的哲学问题。

“反事实”可能作为名词出现在物理讨论中。在这种情况下的意思是“一个可以被测量但因故没有被测量的值”。
Inge S. Helland, "A new foundation of quantum mechanics," p. 386: "Counterfactual definiteness is defined as the ability to speak with results of measurements that have not been performed (i.e., the ability to assure the existence of objects, and properties of objects, even when they have not been measured").W. M. de Muynck, W. De Baere, and H. Martens, "Interpretations of Quantum Mechanics, Joint Measurement of Incompatible Observables, and Counterfactual Definiteness" p. 54 says: "Counterfactual reasoning deals with nonactual physical processes and events and plays an important role in physical argumentations. In such reasonings it is assumed that, if some set of manipulations were carried out, then the resulting physical processes would give rise to effects which are determined by the formal laws of the theory applying in the envisaged domain of experimentation.

The physical justification of counterfactual reasoning depends on the context in which it is used. Rigorously speaking, given some theoretical framework, such reasoning is always allowed and justified as soon as one is sure of the possibility of at least one realization of the pre-assumed set of manipulations. In general, in counterfactual reasoning it is even understood that the physical situations to which the reasoning applies can be reproduced at will, and hence may be realized more than once."Text was downloaded from: http://www.phys.tue.nl/ktn/Wim/i1.pdf 

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Category:量子測量