Mysteries

Question

If a quantum system's properties are context-dependent, what implications does this have for the concept of objective reality in the quantum world, and how does this contrast with our everyday, classical understanding of objects having inherent properties regardless of observation?

Synthesized answer

According to the passages, if a quantum system's properties are context-dependent, this directly challenges the classical concept of objective reality. In classical physics, an object is assumed to "own" its properties as if it were "alone in the universe" [1]. However, in quantum mechanics, a property must be attributed to "a system on which a given measurement is made," not to an isolated system [2]. This means that the object to which one attributes physical properties is not "a system" but "a system within a context" [1][2].

This contrasts sharply with our everyday classical understanding, where objects are thought to have inherent properties (like position or velocity) regardless of observation [4]. The passages state that in quantum mechanics, it is "impossible to say that a quantum particle 'owns' a property" in the classical sense [4][5]. While some properties like mass may belong to a system in a classical way, most properties are contextual [5]. The passages argue that this contextual quantization is not paradoxical but is simply the behavior of nature, and accepting it removes many apparent contradictions in the quantum world [1].

Synthesized from the book passages below. Chat with the book on Feynman for follow-up.

From the book

ere, and one must consider probability amplitudes, which allow one to get a physical picture of Born’s law in this case. The change of context corresponds then to the passage from a representation where the momentum of the particle is defined, to another “incompatible” one where its position is defined. A usual quantum wave-packet is somewhere between these two extremes, but in any case speaking about particles or waves with a classical behavior is a fiction, sometimes useful but most often misleading. The above examples do not necessarily require to fully determine the modalities, i.e. all…
Passage [18]
ame: certainty and repeatability remain, but under more restrictive conditions than those observed in classical physics. If one legitimately considers that certainty and reproducibility are minimum requirements for a realistic description of the physical world, the inescapable consequence of the above observations is that the object to which one must attribute physical properties is not “a system”, but “a system on which a given measurement is made”, since only in this case the result does not change. Such a “contextual” description is an essential difference from Newtonian physics, and it…
Passage [10]
versity Press (2012). (2) Asher Peres, “Quantum Theory: Concepts and Methods”, Kluwer Academic Publishers (1995). (3) P. Grangier, “Contextual objectivity: a realistic interpretation of quantum mechanics”, European Journal of Physics 23:3, 331 (2002) [arXiv:quant-ph/0012122]. (4) A. Auffèves and P. Grangier, “Contexts, Systems and Modalities: a new ontology for quantum mechanics”, Found. Phys. 46, 121 (2016) [arXiv:1409.2120]. (5) A. Auffèves and P. Grangier, “Deriving Born’s rule from an Inference to the Best Explanation”, Found. Phys. 50, 1781 (2020) [arXiv:1910.13738]. (6) P. Grangier,…
Passage [25]
ch in physics since Newton has been to define objects, to attribute properties to them, and to measure these properties. One then asserts that the object “has” this property, for example that it has a position, a velocity, or a momentum. Does this “natural” approach work in quantum mechanics? Although physicists are extremely reluctant to admit it, the answer is clearly no - and this “no”, correctly interpreted, provides the empirical element that is missing in our understanding of the quantum description of the physical world. So, let’s look at a simple experiment that shows that it is…
Passage [7]
Revisiting Quantum Mysteries. Philippe Grangier philippe.grangier@institutoptique.fr Laboratoire Charles Fabry, Institut d’Optique Graduate School, CNRS, Université Paris Saclay, F 91127 Palaiseau, France, Abstract In this article we argue that in quantum mechanics, and in opposition to classical physics, it is impossible to say that an isolated quantum system “owns” a physical property. Some properties of the system, its mass for example, belong to it in a sense close to that of classical physics; but most often a property must be attributed to the system within a context. We give simple…
Passage [2]

More questions about this book