scholarly journals Paradoxes and Primitive Ontology in Collapse Theories of Quantum Mechanics

2018 ◽  
pp. 134-153
Keyword(s):  
Quantum Mechanics ◽  
Primitive Ontology ◽  
Collapse Theories

scholarly journals Observing a superposition

Synthese ◽  
2021 ◽  
Author(s):  
Paul Skokowski
Keyword(s):  
Quantum Mechanics ◽  
Careful Consideration ◽  
False Beliefs ◽  
Belief States ◽  
Collapse Theories

AbstractThe bare theory is a no-collapse version of quantum mechanics which predicts certain puzzling results for the introspective beliefs of human observers of superpositions. The bare theory can be interpreted to claim that an observer can form false beliefs about the outcome of an experiment which produces a superpositional result. It is argued that, when careful consideration is given to the observer’s belief states and their evolution, the observer does not end up with the beliefs claimed. This result leads to questions about whether there can be any allure for no-collapse theories as austere as the bare theory.

Philosophy of Quantum Mechanics: Dynamical Collapse Theories

2021 ◽  
Author(s):  
Angelo Bassi
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
New Technologies ◽  
Stochastic Dynamics ◽  
Laws Of Nature ◽  
Nonlinear Effects ◽  
Foundation Of Quantum Mechanics ◽  
Quantum Phenomena ◽  
The One ◽  
Collapse Theories

Quantum Mechanics is one of the most successful theories of nature. It accounts for all known properties of matter and light, and it does so with an unprecedented level of accuracy. On top of this, it generated many new technologies that now are part of daily life. In many ways, it can be said that we live in a quantum world. Yet, quantum theory is subject to an intense debate about its meaning as a theory of nature, which started from the very beginning and has never ended. The essence was captured by Schrödinger with the cat paradox: why do cats behave classically instead of being quantum like the one imagined by Schrödinger? Answering this question digs deep into the foundation of quantum mechanics. A possible answer is Dynamical Collapse Theories. The fundamental assumption is that the Schrödinger equation, which is supposed to govern all quantum phenomena (at the non-relativistic level) is only approximately correct. It is an approximation of a nonlinear and stochastic dynamics, according to which the wave functions of microscopic objects can be in a superposition of different states because the nonlinear effects are negligible, while those of macroscopic objects are always very well localized in space because the nonlinear effects dominate for increasingly massive systems. Then, microscopic systems behave quantum mechanically, while macroscopic ones such as Schrödinger’s cat behave classically simply because the (newly postulated) laws of nature say so. By changing the dynamics, collapse theories make predictions that are different from quantum-mechanical predictions. Then it becomes interesting to test the various collapse models that have been proposed. Experimental effort is increasing worldwide, so far limiting values of the theory’s parameters quantifying the collapse, since no collapse signal was detected, but possibly in the future finding such a signal and opening up a window beyond quantum theory.

An interactions-based interpretation for quantum mechanics

2020 ◽  
Vol 33 (1) ◽  
pp. 1-9
Author(s):  
J. M. Kerr
Keyword(s):  
Wave Function ◽  
Quantum Mechanics ◽  
Small Group ◽  
Planck Scale ◽  
Direct Result ◽  
Conceptual Basis ◽  
State Reduction ◽  
Background Theory ◽  
Collapse Theories ◽  
Epistemic Aspect

A small group of simple, lateral assumptions about the structure and nature of space, some of them at the Planck scale, produces a new conceptual basis. The background theory allows a rederivation of several areas of theory it interprets, leading in other areas to alternative mathematics that closely mimics existing physics, but diverging enough for testable predictions. This paper focusses on the phenomenology of quantum mechanics (QM), with a nonlocal interpretation, in which the wave function is primarily ontic, but also has an epistemic aspect. It differs widely from all other interpretations for QM, but has general similarities to some objective collapse theories, and in particular to relational QM (RQM). State reduction is set off by interactions, not measurements, but unlike in RQM, the “exchange of information” between two systems is not only made possible by the interaction, it is a direct result of it. The interpretation includes an explanation for quantization, the probabilistic aspect of QM, entanglement, and state reduction as in decoherence.

The Collapse of the Quantum State

2019 ◽  
pp. 118-142
Author(s):  
Jeffrey A. Barrett
Keyword(s):  
Quantum Mechanics ◽  
Quantum State ◽  
Quantum Measurement ◽  
Measurement Problem ◽  
Primitive Ontology ◽  
Quantum Measurement Problem

We consider Wigner’s proposal for solving the quantum measurement problem. His solution involves a strong mind-body dualism, but it is also possible to provide a purely physical collapse solution to the quantum measurement problem. To this end, we consider the GRW formulation of quantum mechanics and three ways one might interpret it: GRWr, GRWm, and GRWf. These ways of interpreting the theory differ in the metaphysical commitments one makes and, hence, in how one explains one’s measurement records and hence one’s experience. This provides an introduction to the notions of an empirical ontology and a primitive ontology. We consider some of the comparative virtues and vices of the GRW formulation of quantum mechanics.

6. Interpreting the quantum

2021 ◽  
pp. 110-132
Author(s):  
David Wallace
Keyword(s):  
Quantum Mechanics ◽  
Narrow Range ◽  
Scientific Practice ◽  
Experimental Results ◽  
Interpretation Of Quantum Mechanics ◽  
Correct Interpretation ◽  
Hidden Variable ◽  
Hidden Variable Theories ◽  
Scientific Results ◽  
Collapse Theories

This chapter surveys various proposals to interpret—that is, make sense of—quantum mechanics. We could attempt to think of quantum mechanics in purely instrumentalist terms, as an algorithm to predict observed experimental results. But this fits badly with scientific practice and is probably not viable. We could attempt to modify quantum mechanics itself to resolve the paradoxes, and there are some simple models that attempt to do that: some are ‘hidden-variable’ theories that add extra properties to the theory, some are ‘dynamical-collapse’ theories that modify the theory’s equations. But none of these models succeed in reproducing quantum theory’s predictions outside a relatively narrow range of applications. Or we could try to take the apparent indefiniteness of quantum mechanics literally, and interpret it as a theory of many parallel worlds. The correct interpretation of quantum mechanics remains controversial, but the search for understanding and interpretation of the theory has led to very substantial scientific results and is likely to lead to more.

scholarly journals Interpretive analogies between quantum and statistical mechanics

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
C. D. McCoy
Keyword(s):  
Quantum Mechanics ◽  
Statistical Mechanics ◽  
Quantum Measurement ◽  
Measurement Problem ◽  
Initial Conditions ◽  
Primitive Ontology ◽  
Quantum Measurement Problem ◽  
Classical Statistical Mechanics ◽  
Interpretive Strategies ◽  
Significant Application

AbstractThe conspicuous similarities between interpretive strategies in classical statistical mechanics and in quantum mechanics may be grounded on their employment of common implementations of probability. The objective probabilities which represent the underlying stochasticity of these theories can be naturally associated with three of their common formal features: initial conditions, dynamics, and observables. Various well-known interpretations of the two theories line up with particular choices among these three ways of implementing probability. This perspective has significant application to debates on primitive ontology and to the quantum measurement problem.

scholarly journals Non-Markovian wave-function collapse models are Bohmian-like theories in disguise

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 594
Author(s):  
Antoine Tilloy ◽  
Howard M. Wiseman
Keyword(s):  
Wave Function ◽  
Quantum Mechanics ◽  
Schrödinger Equation ◽  
Schrodinger Equation ◽  
Initial Conditions ◽  
Hidden Variables ◽  
Bohmian Mechanics ◽  
Primitive Ontology ◽  
Collapse Model ◽  
Collapse Models

Spontaneous collapse models and Bohmian mechanics are two different solutions to the measurement problem plaguing orthodox quantum mechanics. They have, a priori nothing in common. At a formal level, collapse models add a non-linear noise term to the Schrödinger equation, and extract definite measurement outcomes either from the wave function (e.g. mass density ontology) or the noise itself (flash ontology). Bohmian mechanics keeps the Schrödinger equation intact but uses the wave function to guide particles (or fields), which comprise the primitive ontology. Collapse models modify the predictions of orthodox quantum mechanics, whilst Bohmian mechanics can be argued to reproduce them. However, it turns out that collapse models and their primitive ontology can be exactly recast as Bohmian theories. More precisely, considering (i) a system described by a non-Markovian collapse model, and (ii) an extended system where a carefully tailored bath is added and described by Bohmian mechanics, the stochastic wave-function of the collapse model is exactly the wave-function of the original system conditioned on the Bohmian hidden variables of the bath. Further, the noise driving the collapse model is a linear functional of the Bohmian variables. The randomness that seems progressively revealed in the collapse models lies entirely in the initial conditions in the Bohmian-like theory. Our construction of the appropriate bath is not trivial and exploits an old result from the theory of open quantum systems. This reformulation of collapse models as Bohmian theories brings to the fore the question of whether there exists `unromantic' realist interpretations of quantum theory that cannot ultimately be rewritten this way, with some guiding law. It also points to important foundational differences between `true' (Markovian) collapse models and non-Markovian models.

Scientific Realism without the Wave Function

2020 ◽  
pp. 212-228
Author(s):  
Valia Allori
Keyword(s):  
Wave Function ◽  
Quantum Mechanics ◽  
Scientific Realism ◽  
Theory Construction ◽  
Scientific Theories ◽  
Primitive Ontology ◽  
Theory Evaluation ◽  
Spatio Temporal ◽  
True Quantum

Scientific realism assumes that our best scientific theories can be regarded as (approximately) true. Quantum mechanics has long been regarded as at odds with scientific realism. It is now known that this is not true. However, scientific realists usually assume that the wave function represents physical entities. Chapter 11 discusses a particular approach which makes quantum mechanics compatible with scientific realism without assuming this: matter is instead represented by some spatio-temporal entity dubbed the primitive ontology. It argues how within this framework one developsa distinctive theory-construction schema, which allows us to perform a more informed theory evaluation by analyzing the various ingredients of the approach and their inter-relations.

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