1998/01/01 by Adrian Kent · 3 citations
Chemistry · Physics and Astronomy · #History and advancements in chemistry #Quantum Mechanics and Applications #Statistical Mechanics and Entropy #gr-qc #hep-th #quant-ph
paper · pdf · doi:10.1238/physica.topical.076a00078
published as Phys.Scripta T76 (1998) 78-84 · 19 pages, TeX with harvmac. Contribution to Proceedings of the 104th Nobel Symposium, ``Modern Studies of Basic Quantum Concepts and Phenomena'', Gimo, June 1997. To appear in Physica Scripta
openalex publication_date 1998/01/01 · arxiv created 1998/09/04 · arxiv updated 2009/11/30 · openalex created_date 2020/07/02 · openalex updated_date 2026/07/30
There are good motivations for considering some type of quantum histories formalism. Several possible formalisms are known, defined by different definitions of event and by different selection criteria for sets of histories. These formalisms have a natural interpretation, according to which nature somehow chooses one set of histories from among those allowed, and then randomly chooses to realise one history from that set; other interpretations are possible, but their scientific implications are essentially the same. The selection criteria proposed to date are reasonably natural, and certainly raise new questions. For example, the validity of ordering inferences which we normally take for granted – such as that a particle in one region is necessarily in a larger region containing it – depends on whether or not our history respects the criterion of ordered consistency, or merely consistency. However, the known selection criteria, including consistency and medium decoherence, are very weak. It is not possible to derive the predictions of classical mechanics or Copenhagen quantum mechanics from the theories they define, even given observational data in an extended time interval. Attempts to refine the consistent histories approach so as to solve this problem by finding a definition of quasiclassicality have so far not succeeded. On the other hand, it is shown that dynamical collapse models, of the type originally proposed by Ghirardi-Rimini-Weber, can be re-interpreted as set selection criteria within a quantum histories framework, in which context they appear as candidate solutions to the set selection problem. This suggests a new route to relativistic generalisation of these models, since covariant definitions of a quantum event are known.