Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:quant-ph/0112005 · Journal of Optics B Quantum and Semiclassical Optics

Seven steps towards the classical world

Valia Allori, Detlef D uuml rr, Shelly Goldstein, Nino Zangh�

Published Aug 1, 2002• 63 citations
arXivHTMLPDF

Abstract

Classical physics is about real objects, like apples falling from trees, whose motion is governed by Newtonian laws. In standard quantum mechanics only the wavefunctions or the results of measurements exist, and to answer the question of how the classical world can be part of the quantum world is a rather formidable task. However, this is not the case for Bohmian mechanics which, like classical mechanics, is a theory about real objects. In Bohmian terms, the problem of the classical limit becomes very simple: when do the Bohmian trajectories look Newtonian?

DOI
10.1088/1464-4266/4/4/344

Related papers

Quantum Mechanics as Classical Physics

Charles T. Sebens

Here I explore a novel no-collapse interpretation of quantum mechanics that combines aspects of two familiar and well-developed alternatives, Bohmian mechanics and the many-worlds interpretation. Despite reproducing the empirical predictions of quantum mechanics, the theory looks surprisingly classical. All there is at the fundamental level are particles interacting via Newtonian forces. There is no wave function. However, there are many worlds.

arXiv:1403.0014•Philosophy of Science•Apr 1, 2015•48 citations

Introduction: Three Worlds

Gary E. Bowman

This introductory chapter outlines the differences between classical physics and quantum physics by positing three imaginary worlds. World 1 is governed by the laws of classical Newtonian mechanics, World 2 by classical field physics, and World 3 by quantum physics. The point is that classical physics deals with well-defined, continuously-existing physical quantities, including trajectories, while quantum physics is fundamentally about physical quantities defined in terms of probability functions.

Oxford University Press eBooks•Nov 1, 2007•0 citations

Bohmian mechanics and the emergence of classicality

A. Matzkin

Bohmian mechanics is endowed with an ontological package that supposedly allows to solve the main interpretational problems of quantum mechanics. We are concerned in this work by the emergence of classicality from the quantum mechanical substrate. We will argue that although being superficially attractive, the de Broglie-Bohm interpretation does not shed new light on the quantum-to-classical transition. This is due to nature of the dynamical law of Bohmian mechanics by which the particles follow the streamlines of the probability flow. As a consequence, Bohmian trajectories can be highly non-classical even when the wavefunction propagates along classical trajectories, as happens in semiclassical systems. In order to account for classical dynamics, Bohmian mechanics needs non-spreading and non-interfering wave packets: this is achieved for practical purposes by having recourse to decoherence and dense measurements. However one then faces the usual fundamental problems associated with the meaning of reduced density matrices. Moreover the specific assets of the de Broglie-Bohm interpretation – in particular the existence of point-like particles pursuing well-defined trajectories – would play no role in accounting for the emergence of classical dynamics.

Journal of Physics Conference Series•Jun 1, 2009•0 citations

Bohmian Mechanics

Detlef Duerr, Sheldon Goldstein, Roderich Tumulka +1 more

Bohmian mechanics is a theory about point particles moving along trajectories. It has the property that in a world governed by Bohmian mechanics, observers see the same statistics for experimental results as predicted by quantum mechanics. Bohmian mechanics thus provides an explanation of quantum mechanics. Moreover, the Bohmian trajectories are defined in a non-conspiratorial way by a few simple laws.

arXiv:0903.2601•Mar 15, 2009•1 citation

Basic elements of Bohmian mechanics

Emmanuel E. Haven, Andrei Yu. Khrennikov

Short introduction to Bohmian mechanics Sheldon Goldstein in a Foundations of Physics paper [1] indicates (p. 341): “Since macroscopic objects are normally regarded as built out of microscopic constituents …there can be no problem of macroscopic reality per se in Bohmian mechanics.” Goldstein in the same paper remarks (p. 342) that this | ψ | 2 has “a status very much the same as that of a thermodynamic equilibrium.” Basil Hiley the closest collaborator of David Bohm, says the following (Hiley [2] (p. 2)): “What Bohm (1952a; 1952b) did was to show how to retain a description of all the usual properties of a classical world and yet remain completely within the quantum formalism.” The Bohm (1952) [3] [4] references in that quote refer to the original work of Bohm in which he sets out the basics of the Bohmian mechanics. As we will see later in the next section of this chapter, the appearance of an “additional term” in the Hamilton-Jacobi equation, is the hallmark of Bohmian mechanics and it is very often termed the “quantum potential.” Hiley [2] (p. 2) remarks that since the Bohmian momentum is a well-defined function of position and time, an ensemble of trajectories can be found when the quantum potential is non-zero. A unique, classical path is found when the quantum potential is zero. From the outset, we hope the reader can savor the beauty of this simple but very powerful result. Bohmian mechanics indeed shows this very gentle transition from quantum mechanics to classical mechanics via the value of the quantum potential.

Cambridge University Press eBooks•Jan 17, 2013•0 citations

A Proposal for the Classical Limit in Bohm's Theory

Davide Romano

In this paper, I describe a general strategy for deriving Newtonian mechanics from Bohm’s theory in the classical macroscopic regime. The strategy is based on two main steps: (i) the use of open systems, leading to the formation of independent subsystems; (ii) the analysis of the quantum potential for the emergent subsystems. The first step leads to and explains (within the Bohmian framework) the well-known phenomenon of decoherence. The second one provides a precise criterion for the emergence of Newtonian trajectories. In particular, I will show that, under reasonable classicality conditions, the quantum potential of the emergent subsystems becomes negligible. As a consequence, these systems will follow an approximately Newtonian dynamics.

•Aug 3, 2019•0 citations
Classical physics is about real objects, like apples falling from trees, whose motion is governed by Newtonian laws. In standard quantum mechanics only the wavefunctions or the results of measurements exist, and to answer the question of how the classical world can be part of the quantum world is a rather formidable task. However, this is not the case for Bohmian mechanics which, like classical mechanics, is a theory about real objects. In Bohmian terms, the problem of the classical limit becomes very simple: when do the Bohmian trajectories look Newtonian?
This introductory chapter outlines the differences between classical physics and quantum physics by positing three imaginary worlds. World 1 is governed by the laws of classical Newtonian mechanics, World 2 by classical field physics, and World 3 by quantum physics. The point is that classical physics deals with well-defined, continuously-existing physical quantities, including trajectories, while quantum physics is fundamentally about physical quantities defined in terms of probability functions.
Bohmian mechanics is endowed with an ontological package that supposedly allows to solve the main interpretational problems of quantum mechanics. We are concerned in this work by the emergence of classicality from the quantum mechanical substrate. We will argue that although being superficially attractive, the de Broglie-Bohm interpretation does not shed new light on the quantum-to-classical transition. This is due to nature of the dynamical law of Bohmian mechanics by which the particles follow the streamlines of the probability flow. As a consequence, Bohmian trajectories can be highly non-classical even when the wavefunction propagates along classical trajectories, as happens in semiclassical systems. In order to account for classical dynamics, Bohmian mechanics needs non-spreading and non-interfering wave packets: this is achieved for practical purposes by having recourse to decoherence and dense measurements. However one then faces the usual fundamental problems associated with the meaning of reduced density matrices. Moreover the specific assets of the de Broglie-Bohm interpretation – in particular the existence of point-like particles pursuing well-defined trajectories – would play no role in accounting for the emergence of classical dynamics.
Short introduction to Bohmian mechanics Sheldon Goldstein in a Foundations of Physics paper [1] indicates (p. 341): “Since macroscopic objects are normally regarded as built out of microscopic constituents …there can be no problem of macroscopic reality per se in Bohmian mechanics.” Goldstein in the same paper remarks (p. 342) that this | ψ | 2 has “a status very much the same as that of a thermodynamic equilibrium.” Basil Hiley the closest collaborator of David Bohm, says the following (Hiley [2] (p. 2)): “What Bohm (1952a; 1952b) did was to show how to retain a description of all the usual properties of a classical world and yet remain completely within the quantum formalism.” The Bohm (1952) [3] [4] references in that quote refer to the original work of Bohm in which he sets out the basics of the Bohmian mechanics. As we will see later in the next section of this chapter, the appearance of an “additional term” in the Hamilton-Jacobi equation, is the hallmark of Bohmian mechanics and it is very often termed the “quantum potential.” Hiley [2] (p. 2) remarks that since the Bohmian momentum is a well-defined function of position and time, an ensemble of trajectories can be found when the quantum potential is non-zero. A unique, classical path is found when the quantum potential is zero. From the outset, we hope the reader can savor the beauty of this simple but very powerful result. Bohmian mechanics indeed shows this very gentle transition from quantum mechanics to classical mechanics via the value of the quantum potential.
In this paper, I describe a general strategy for deriving Newtonian mechanics from Bohm’s theory in the classical macroscopic regime. The strategy is based on two main steps: (i) the use of open systems, leading to the formation of independent subsystems; (ii) the analysis of the quantum potential for the emergent subsystems. The first step leads to and explains (within the Bohmian framework) the well-known phenomenon of decoherence. The second one provides a precise criterion for the emergence of Newtonian trajectories. In particular, I will show that, under reasonable classicality conditions, the quantum potential of the emergent subsystems becomes negligible. As a consequence, these systems will follow an approximately Newtonian dynamics.