The Bare Theory and How to Fix It

Quantum mechanic~ without the collapse postulate, the ~ theory, wa.p roposed by Alben (1992) as a way of understanding Everett's relative-state fonnulation of quantum mechanics. The basic idea is to try to account for an observer's beliefs by appealing to a type of illusion predicted by the bare dteory. This paper respond~ to some recent objections to the bare thet)ry by providing a more detailed description of the sense in which it can and the sense in which it cannot account for our experience.

ABSTRACf. Everett proposed resolving the quantum measurement problem by dropping the nonlinear collapse dynamics from quantum mechanics and taking what is left as a complete physical theory. If one takes such a proposal seriously. then the question becomes how much of the predictive and explanatory power of the standard theory can one recover without the collapse postulate and without adding anything else. Quantum mechanics without the collapse postulate has several suggestive properties. which we will consider in some detail. While these properties are not enough to make it acceptable given the usual standards for a satisfactory physical theory. one might want to exploit these properties to cook up a satisfactory no-collapse formulation of quantum mechanics. In considering how this might work. we will see why any no-collapse theory must generally fail to satisfy at least one of tWo plausible-sounding conditions.

arXiv (Cornell University), 2019

Recent experiments (gedanken or otherwise) and theorems in quantum mechanics (QM), such as new iterations on Wigner's friend and delayed choice, have led many people to claim that QM is not compatible with determinate and intersubjectively consistent experience (what some call absoluteness of observed events), such as experiences of experimental outcomes. In the case of delayed choice the tension is between our experience of free will and a possible "superdeterminism" at work in QM. At the very least, some have suggested that the only way to save absoluteness of observed events, is to give up one or more of the following assumptions: free will, locality, or the completeness of QM. Our goal in this paper is to provide a take on QM that explains why there is and must always be determinate and intersubjectively consistent experience about all experimental outcomes (absoluteness of observed events). Our take accepts the completeness of the theory and requires no invocation of relative states (e.g., outcomes being relative to branches, conscious observers, etc.). And finally, this take requires no allegedly hybrid models such as claims about "subjective collapse." We provide a take on QM that yields a single world wherein all the observers (conscious or otherwise) agree about determinate and definite outcomes, because those outcomes are in fact determinate and definite. We provide a realist psi-epistemic take on QM that saves the absoluteness of observed events and the completeness of QM, without giving up free will or locality. We also show how our realist psi-epistemic account eliminates the measurement problem and, coupled with our take on neutral monism, also eliminates the hard problem of consciousness. The key to all this is to let go of the following offending assumptions: 1) physicalism, 2) fundamentalism, and relatedly 3) dualism about conscious experience, 4) the notion that fundamental explanation is always constructive, causal or dynamical, and relatedly, 5) realism about the wavefunction. Together these assumptions force us into the hard problem, they force us into the measurement problem, and they force us to seek the solutions to these problems in fundamental physics, e.g., by trying to relate these problems to one another directly, with very little success. Sometimes, when a problem is deeply intractable the best move is to jettison the offending assumptions that led to the problem in the first place. This is precisely what we do herein.

The central part of Everett's formulation of quantum mechanics is a quantum mechanical model of memory and of observation as the recording of information in a memory. To use this model as an answer to the measurement problem, Everett has to assume that a conscious observer can be in a superposition of such memory states and be unaware of it. This assumption has puzzled generations of readers. The fundamental aim of this dissertation is to find a set of simpler assumptions which are sufficient to show that Everett's model is empirically adequate. I argue that Everett's model needs three assumptions to account for the process of observation: an assumption of decoherence of observers as quantum mechanical systems; an assumption of supervenience of mental states (qualities) over quantum mechanical properties; and an assumption about the interpretation of quantum mechanical states in general: quantum mechanical states describe ensembles of states of affairs coexisting in the same system. I argue that the only plausible understanding of such ensembles is as ensembles of possibilities, and that all standard no-collapse interpretations agree in this reading of quantum mechanical states. Their differences can be understood as different theories about what marks the real state within this ensemble, and Everett's theory as the claim that no additional 'mark of reality' is necessary. Using the three assumptions, I argue that introspection cannot determine the objective quantum mechanical state of an observer. Rather, the introspective qualities of a quantum mechanical state can be represented by a (classical) statistical ensemble of subjective states. An analysis of these subjective states and their dynamics leads to the conclusion that they suffice to give empirically correct predictions. The argument for the empirical adequacy of the subjective state entails that knowledge of the objective quantum mechanical state is impossible in principle. Empirical reality for a conscious observer is not described by the objective state, but by a Everettian relative state conditional on the subjective state, and no theoretical 'mark of reality' is necessary for this concept of reality. I compare the resulting concept of reality to Kant's distinction between empirical and transcendental reality.

arXiv (Cornell University), 2019

Recent experiments (gedanken or otherwise) and theorems in quantum mechanics (QM), such as new iterations on Wigner's friend and delayed choice, have led many people to claim that QM is not compatible with determinate and intersubjectively consistent experience (what some call absoluteness of observed events), such as experiences of experimental outcomes. In the case of delayed choice the tension is between our experience of free will and a possible "superdeterminism" at work in QM. At the very least, some have suggested that the only way to save absoluteness of observed events, is to give up one or more of the following assumptions: free will, locality, or the completeness of QM. Our goal in this paper is to provide a take on QM that explains why there is and must always be determinate and intersubjectively consistent experience about all experimental outcomes (absoluteness of observed events). Our take accepts the completeness of the theory and requires no invocation of relative states (e.g., outcomes being relative to branches, conscious observers, etc.). And finally, this take requires no allegedly hybrid models such as claims about "subjective collapse." We provide a take on QM that yields a single world wherein all the observers (conscious or otherwise) agree about determinate and definite outcomes, because those outcomes are in fact determinate and definite. We provide a realist psi-epistemic take on QM that saves the absoluteness of observed events and the completeness of QM, without giving up free will or locality. We also show how our realist psi-epistemic account eliminates the measurement problem and, coupled with our take on neutral monism, also eliminates the hard problem of consciousness. The key to all this is to let go of the following offending assumptions: 1) physicalism, 2) fundamentalism, and relatedly 3) dualism about conscious experience, 4) the notion that fundamental explanation is always constructive, causal or dynamical, and relatedly, 5) realism about the wavefunction. Together these assumptions force us into the hard problem, they force us into the measurement problem, and they force us to seek the solutions to these problems in fundamental physics, e.g., by trying to relate these problems to one another directly, with very little success. Sometimes, when a problem is deeply intractable the best move is to jettison the offending assumptions that led to the problem in the first place. This is precisely what we do herein.

2007

Quantum theory is applicable, in principle, to both the microscopic and macroscopic realms. It is therefore worthwhile to investigate whether it is possible to evolve a quantum-compatible view of the properties and states of macroscopic objects in everyday thinking. It will allow a realistic interpretation of quantum theory in a manner directly consistent with the observations. The construction of such

Philosophy of Science, 2013

The paradox of Wigner's friend challenges the objectivity of description in quantum theory. A pragmatist interpretation can meet this challenge by judicious appeal to decoherence. On this interpretation, quantum theory provides situated agents with resources for predicting and explaining what happens in the physical world-not conscious observations of it. Even in Wigner's friend scenarios, differently situated agents agree on the objective content of statements about the values of physical magnitudes. In more realistic circumstances quantum Darwinism also permits differently situated agents equal observational access to evaluate their truth. In this view, quantum theory has nothing to say about consciousness or conscious experiences of observers. But it does prompt us to reexamine the significance even of everyday claims about the physical world.

arXiv (Cornell University), 2019

The interpretation of quantum mechanics has been discussed since this theme first was brought up by Einstein and Bohr. This article describes a proposal for a new foundation of quantum theory, partly drawing upon ideas from statistical inference theory. The approach can be said to have an intuitive basis: The quantum states of a physical system are under certain conditions in one-to-one correspondence with the following: 1) Focus on a concrete question to nature and then 2) give a definite answer to this question. This foundation implies an epistemic interpretation, depending upon the observer, but the objective world is restored when all observers agree on their observations on some variables. The article contains a survey of parts of the author's books on epistemic processes, which give more details about the theory. At the same time, the article extends some of the discussion in the books, and at places makes it more precise. For further development of interpretation issues, I need cooperation with interested physicists.

Entropy 2021, 23, 1197, 2021

This article reconsiders the concept of physical reality in quantum theory and the concept of quantum measurement, following Bohr, whose analysis of quantum measurement led him to his concept of a (quantum) “phenomenon,” referring to “the observations obtained under the specified circumstances,” in the interaction between quantum objects and measuring instruments. This situation makes the terms “observation” and “measurement,” as conventionally understood, inapplicable. These terms are remnants of classical physics or still earlier history, from which classical physics inherited it. As defined here, a quantum measurement does not measure any preexisting property of the ultimate constitution of the reality responsible for quantum phenomena. An act of measurement establishes a quantum phenomenon by an interaction between the instrument and the quantum object or in the present view the ultimate constitution of the reality responsible for quantum phenomena and, at the time of measurement, also quantum objects. In the view advanced in this article, in contrast to that of Bohr, quantum objects, such as electrons or photons, are assumed to exist only at the time of measurement and not independently, a view that redefines the concept of quantum object as well. This redefinition becomes especially important in high-energy quantum regimes and quantum field theory and allows this article to define a new concept of quantum field. The article also considers, now following Bohr, the quantum measurement as the entanglement between quantum objects and measurement instruments. The argument of the article is grounded in the concept “reality without realism” (RWR), as underlying quantum measurement thus understood, and the view, the RWR view, of quantum theory defined by this concept. The RWR view places a stratum of physical reality thus designated, here the reality ultimately responsible for quantum phenomena, beyond representation or knowledge, or even conception, and defines the corresponding set of interpretations quantum mechanics or quantum field theory, such as the one assumed in this article, in which, again, not only quantum phenomena but also quantum objects are (idealizations) defined by measurement. As such, the article also offers a broadly conceived response to J. Bell’s argument “against ‘measurement’”.