One stochastic single-world theory recently in arXiv:
https://arxiv.org/abs/1809.10427 : Evolving Realities for Quantum Measure Theory Henry Wilkes <https://arxiv.org/search/quant-ph?searchtype=author&query=Wilkes%2C+H> (Submitted on 27 Sep 2018) We introduce and explore Rafael Sorkin's \textit{evolving co-event scheme}: a theoretical framework for determining completely which events do and do not happen in evolving quantum, or indeed classical, systems. The theory is observer-independent and constructed from discrete histories, making the framework a potential setting for discrete quantum cosmology and quantum gravity, as well as ordinary discrete quantum systems. The foundation of this theory is Quantum Measure Theory, which generalises (classical) measure theory to allow for quantum interference between alternative histories; and its co-event interpretation, which describes whether events can or can not occur, and in what combination, given a system and a quantum measure. In contrast to previous co-event schemes, the evolving co-event scheme is applied in stages, in the stochastic sense, without any dependence on later stages, making it manifestly compatible with an evolving block view. It is shown that the co-event realities produced by the basic evolving scheme do not depend on the inclusion or exclusion of zero measure histories in the history space, which follows non-trivially from the basic rules of the scheme. It is also shown that this evolving co-event scheme will reduce to producing classical realities when it is applied to classical systems. Apparently young Henry Wilkes recently finished his PhD thesis: https://spiral.imperial.ac.uk/bitstream/10044/1/70797/1/Wilkes-H-2019-PhD-Thesis.pdf https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.778048 *The form and interpretation of the decoherence functional* Wilkes, Henry Luka Abstract: In this thesis we will explore the development of a realist quantum theory based on the decoherence functional using the co-event interpretation of Quantum Measure Theory. The Sum-Over-Histories theory of quantum mechanics will provide the bedding for a Hilbert-space-free stochastic-like theory that can accommodate spacetime-like objects, and can therefore be applied to quantum gravity and cosmology, as well as give an alternative perspective on quantum phenomena. The primitive objects of the theory are histories, which give different accounts of a system's evolution, and the decoherence functional, which sums the quantum interference between these histories. Quantum Measure Theory and Generalised Quantum Mechanics (a theory close to Decoherent Histories) then give alternative interpretations of the decoherence functional's relation to reality. In these theories, the decoherence functional is mathematically constrained in analogue to probability measures. However, one of the conditions, called weak positivity, can be lost under composition of isolated systems. We will extend this composition argument to take the case for a stronger condition of strong positivity for decoherence functionals. The bulk of the report will then focus on the co-event interpretation of Quantum Measure Theory, where co-events give full accounts of which events do or do not occur for a given system. The quantum nature of reality is expressed through the breaking of classical logic within these co-event descriptions. We will focus on evolving co-event schemes, which dynamically construct co-events to describe the reality of an evolving system in tandem with its progression. The evolving co-event schemes will be shown to reproduce classical logic when they are applied to classical systems. Moreover, similar to classical stochastic theory, these schemes will be shown to be invariant under the inclusion or exclusion of non-interfering histories. We will also explore a number of outstanding problems for these schemes, and will propose some potential modifications. @philipthrift On Saturday, February 8, 2020 at 2:48:22 PM UTC-6, Brent wrote: > > The problem of SW theories is that they had to postulate measurement as > special kind of random event, which seemed at first to be defined only in > relation to the mind of the measurer. So it got tangled up with the > mind-body problem. This was largely relieved by decoherence theory which > explained measurement as a purely physical process. If decoherence theory > had been better developed before Everett, MWI might never have become an > attractive interpretation. MWI got rid of the special random event by > postulating that all results happened, just to different copies of the > experimenter or intstrument. But it still left a gap as to what physically > constituted the branching process and how did this process result in the > Born rule. > > Brent > > On 2/8/2020 4:06 AM, Philip Thrift wrote: > > > > On Friday, February 7, 2020 at 10:19:58 PM UTC-6, Bruce wrote: > > A stochastic single-world theory is perfectly able to account for what we >> see. >> >> Bruce >> > > > > *Victor Stenger* said this from the time I first connected with him over > 20 years ago. > > It is rare to find any physicist in popular media that believes this. > *Sabine Hossenfelder* doesn't believe this. > > @philipthrift > > > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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