26 research outputs found
Primitive Ontology and the Structure of Fundamental Physical Theories
For a long time it was believed that it was impossible to be realist about quantum mechanics. It took quite a while for the researchers in the foundations of physics, beginning with John Stuart Bell [Bell 1987], to convince others that such an alleged impossibility had no foundation. Nowadays there are several quantum theories that can be interpreted realistically, among which Bohmian mechanics, the GRW theory, and the many-worlds theory. The debate, though, is far from being over: in what respect should we be realist regarding these theories? Two diff erent proposals have been made: on the one hand, there are those who insist on a direct ontological interpretation of the wave function as representing physical bodies, and on the other hand there are those who claim that quantum mechanics is not really about the wave function. In this paper we will present and discuss one proposal of the latter kind that focuses on the notion of primitive ontolog
A thought experiment in many worlds
The many-worlds interpretation of quantum mechanics (MWI) is based on three key assumptions: (1) the completeness of the physical description by means of the wave function, (2) the linearity of the dynamics for the wave function, and (3) multiplicity. In this paper, I propose a new thought experiment in which a post-measurement superposition undergoes no net change while individual branches do change under certain unitary time evolution. Moreover, I argue that MWI gives contradictory predictions for this experiment. In order to avoid the contradiction and save many worlds, it seems that we must drop one or both of the first two assumptions
A thought experiment in many worlds
The many-worlds interpretation of quantum mechanics (MWI) is based on three key assumptions: (1) the completeness of the physical description by means of the wave function, (2) the linearity of the dynamics for the wave function, and (3) multiplicity. In this paper, I propose a new thought experiment in which a post-measurement superposition undergoes no net change while individual branches do change under certain unitary time evolution. Moreover, I argue that MWI gives contradictory predictions for this experiment. In order to avoid the contradiction and save many worlds, it seems that we must drop one or both of the first two assumptions
Position Measurements and the Empirical Status of Particles in Bohmian Mechanics
The paper addresses the debate about the empirical status of particles versus wave functions in Bohmian quantum mechanics. It thereby clarifies questions and misconceptions about the role of the particles in the measurement process, the (un)reliability of position measurements ("surrealistic trajectories"), and the limited empirical access to particle positions ("absolute uncertainty"). Taking the ontological commitment of Bohmian mechanics seriously, all relevant empirical results follow from an analysis of the theory in terms of particle motions. Finally, we address the question, why particle motions rather than patterns in the wave function would be the supervenience base of conscious experience
Some remarks on the mentalistic reformulation of the measurement problem. A reply to S. Gao
Gao (2017) presents a new mentalistic reformulation of the well-known
measurement problem affecting the standard formulation of quantum mechanics.
According to this author, it is essentially a determinate-experience problem,
namely a problem about the compatibility between the linearity of the
Schroedinger's equation, the fundamental law of quantum theory, and definite
experiences perceived by conscious observers. In this essay I aim to clarify
(i) that the well-known measurement problem is a mathematical consequence of
quantum theory's formalism, and that (ii) its mentalistic variant does not
grasp the relevant causes which are responsible for this puzzling issue. The
first part of this paper will be concluded claiming that the "physical"
formulation of the measurement problem cannot be reduced to its mentalistic
version. In the second part of this work it will be shown that, contrary to the
case of quantum mechanics, Bohmian mechanics and GRW theories provide clear
explanations of the physical processes responsible for the definite
localization of macroscopic objects and, consequently, for well-defined
perceptions of measurement outcomes by conscious observers. More precisely, the
macro-objectification of states of experimental devices is obtained exclusively
in virtue of their clear ontologies and dynamical laws without any intervention
of human observers. Hence, it will be argued that in these theoretical
frameworks the measurement problem and the determinate-experience problem are
logically distinct issues
Some remarks on the mentalistic reformulation of the measurement problem. A reply to S. Gao
Gao (2017) presents a new mentalistic reformulation of the well-known measurement problem affecting the standard formulation of quantum mechanics. According to this author, it is essentially a determinate-experience problem, namely a problem about the compatibility between the linearity of the Schrödinger’s equation, the fundamental law of quantum theory, and definite experiences perceived by conscious
observers. In this essay I aim to clarify (i) that the well-known measurement problem is a mathematical consequence of quantum theory’s formalism, and that (ii) its mentalistic variant does not grasp the relevant causes which are responsible for this puzzling issue. The first part of this paper will be concluded claiming that the “physical” formulation of the measurement problem cannot be reduced to its
mentalistic version. In the second part of this work it will be shown that, contrary to the case of quantum mechanics, Bohmian mechanics and GRW theories provide clear explanations of the physical processes responsible for the definite localization of macroscopic objects and, consequently, for well-defined perceptions of measurement outcomes by conscious observers. More precisely, the macro-objectification of
states of experimental devices is obtained exclusively in virtue of their clear ontologies and dynamical laws without any intervention of human observers. Hence, it will be argued that in these theoretical frameworks the measurement problem and the determinate-experience problem are logically distinct issues
The Meaning of the Wave Function: In Search of the Ontology of Quantum Mechanics
The meaning of the wave function has been a hot topic of debate since the
early days of quantum mechanics. Recent years have witnessed a growing interest
in this long-standing question. Is the wave function ontic, directly
representing a state of reality, or epistemic, merely representing a state of
(incomplete) knowledge, or something else? If the wave function is not ontic,
then what, if any, is the underlying state of reality? If the wave function is
indeed ontic, then exactly what physical state does it represent? In this book,
I aim to make sense of the wave function in quantum mechanics and find the
ontological content of the theory. The book can be divided into three parts.
The first part addresses the question of the nature of the wave function
(Chapters 1-5). After giving a comprehensive and critical review of the
competing views of the wave function, I present a new argument for the ontic
view in terms of protective measurements. In addition, I also analyze the
origin of the wave function by deriving the free Schroedinger equation. The
second part analyzes the ontological meaning of the wave function (Chapters 6,
7). I propose a new ontological interpretation of the wave function in terms of
random discontinuous motion of particles, and give two main arguments
supporting this interpretation. The third part investigates whether the
suggested quantum ontology is complete in accounting for our definite
experience and whether it needs to be revised in the relativistic domain
(Chapters 8, 9).Comment: 199 pages, 8 figures. Draft of a forthcoming book. Endorsed by
Stephen L. Adler, GianCarlo Ghirardi, Nicolas Gisin, Peter Holland, and Wayne
Myrvold. To be published in March 2017 by Cambridge University Press
(http://www.cambridge.org/catalogue/catalogue.asp?isbn=9781107124356