Quantum Measurement Problem Research Articles

Kelvin's Baltimore Lectures and Modern Theoretical Physics: Historical and Philosophical Perspectives

In 1884 Sir William Thomson (later Lord Kelvin) delivered a significant series of lectures on physics at the Johns Hopkins University in Baltimore. The lectures remain important because, through their explicit presentation of the theories and metaphysical assumptions of the Newtonian mechanistic tradition, they illuminate the roots of the revolution in physics that began around 1900.This book presents the twenty lectures in their original form for the first time. (A greatly revised version of the lectures appeared in 1904.) In addition, it contains ten original essays in which well-known historians and philosophers of science discuss the physical issues raised in the Baltimore Lectures and developments in theoretical physics since they were delivered.Several of the accompanying essays deal with differences between Kelvin's views of molecular dynamics and the wave theory of light and the ultimately more successful electromagnetic concepts of James Clerk Maxwell. Others consider G. F. FitzGerald's approach to the question of mechanical models and Ernest Rutherford's attitudes toward theoretical matters.The philosophical context of the Baltimore Lectures is taken up, along with the subsequent development of theoretical physics. Several essays reflect upon issues important in the era of relativity and quantum theory - among them the quantum-measurement problem, space-time and action at a distance, parts and wholes, locality and nonlocality, and the transition from natural philosophy to the metaphilosophy of science.Following an introduction by Robert W Kargon, the essayists who address theoretical physics in Kelvin's time and after are P. M. Harmon, Bruce J. Hunt, M. Norton Wise, Crosbie Smith, Howard Stein, Lawrence Badash, Abner Shimony, Paul Teller, John Earman, Arthur Fine, and Thomas Nickles.The editors are affiliated with the Center for the History and Philosophy of Science at the Johns Hopkins University. This volume is the second in a series published by The MIT Press for the Center. The first volume, Observation, Experiment, and Hypothesis in Modern Physical Science, edited by Peter Achinstein and Owen Hannaway, was published in 1985. A Bradford Book.

Spontaneous localization of a system of identical particles

Quantum mechanics with spontaneous localization is a recently proposed stochastic modification of theN-body Schrodinger equation which is consistent both with microphysics and macrophysics and leads to a natural solution of the problem of quantum measurement. The treatment is extended here to systems of identical particles in the framework of the first quantization formalism.

Neutron interference and quantum measurement problems

Physical implications of the neutron interference experiments are discussed from the viewpoint of the many-Hilbert-spaces theory of quantum measurements, which provides a definite criterion for measuring apparatus to give wave packet reduction. We stress that the neutron interference experiments serve for a counter test of quantum measurement theories.

Some epistemological aspects of the quantum measurement problem

Some epistemological aspects of the quantum measurement problem

The insolubility proof of the quantum measurement problem

Modern insolubility proofs of the measurement problem in quantum mechanics not only differ in their complexity and degree of generality, but also reveal a lack of agreement concerning the fundamental question of what constitutes such a proof. A systematic reworking of the (incomplete) 1970 Fine theorem is presented, which is intended to go some way toward clarifying the issue.

Deterministic quantum evolution through modification of the hypotheses of statistical mechanics

It is claimed that for all apparatus capable of performing macroscopic measurements of microscopic systems there exist special internal states for which deterministic quantum evolution alone yields a particular macroscopic outcome rather than a superposition of macroscopically distinct outcomes. We maintain that these special states are distributed uniformly (in a certain sense) among the set of all states. It is hypothesized that for all actually performed experiments the initial conditions lie among the special states. We postulate that in the absence of precise information on apparatus initial conditions one should give equal weight to those microstates that are consistent with the macroscopic stateand are special in the sense used above. Evidence is presented for this postulate's recovering the usual quantum probabilities. This theory is fully deterministic, has no collapsing wave functions, and offers a resolution of the quantum measurement problem through a revision of the usual statistical mechanical handling of initial conditions. It requires a single wave function for the entire universe and an all encompassing conspiracy to arrange the right sort of special wave function for each experiment. In other words, an apparatus is in an appropriate microstate for the experiment that will actually happen even if an ostensibly random process is used to determine that experiment from among apparent alternatives. Although we do not provide physical or philosophical justification for our central hypothesis, some perspective is given by examining the notions implicit in the usual principles of thermodynamics.

The quantum measurement problem and selection of classical states

The problem of selection of preferred basis during passage from quantum to classical systems is treated with the help of a simple example of a 2-state system like the sugar molecule. A simple principle leading to this selection is stated and demonstrated in case of the chosen example. The principle, stated simply is that the preferred basis is the one in which the system environment interaction hamiltonian is diagonal.

Lyapounov variable: Entropy and measurement in quantum mechanics

We discuss the question of the dynamical meaning of the second law of thermodynamics in the framework of quantum mechanics. Previous discussion of the problem in the framework of classical dynamics has shown that the second law can be given a dynamical meaning in terms of the existence of so-called Lyapounov variables-i.e., dynamical variables varying monotonically in time without becoming contradictory. It has been found that such variables can exist in an extended framework of classical dynamics, provided that the dynamical motion is suitably unstable. In this paper we begin to extend these results to quantum mechanics. It is found that no dynamical variable with the characteristic properties of nonequilibrium entropy can be defined in the standard formulation of quantum mechanics. However, if the Hamiltonian has certain well-defined spectral properties, such variables can be defined but only as a nonfactorizable superoperator. Necessary nonfactorizability of such entropy operators M has the consequence that they cannot preserve the class of pure states. Physically, this means that the distinguishability between pure states and corresponding mixtures must be lost in the case of a quantal system for which the algebra of observables can be extended to include a new dynamical variable representing nonequilibrium entropy. We discuss how this result leads to a solution of the quantum measurement problem. It is also found that the question of existence of entropy of superoperators M is closely linked to the problem of defining an operator of time in quantum mechanics.

Entropy, information and Maxwell’s demon after quantum mechanics

The problem of the subjective nature of entropy and its relation to information and irreversibility is examined in the light of the quantum measurement problem. The main thesis of the paper is that state collapse during a measurement and hence entropy increase in the observed universe is seen by observers who are only able to observe a restricted manifold of states determined by their concepts, language, etc., in short by their level of perception. The thesis leads to the assertion that any universe with a structure must evolve.

Irreversibility and quantum measurement—The observer’s role

The role of the observer in physical theories in the sense of the observer’s viewpoint determining prominent features of the observed phenomena is discussed with reference to the problem of irreversibility and quantum measurement, the latter being closely related to the problem of classical behaviour of quantum systems. A completely subjective interpretation of irreversibility is proposed. It is claimed that irreversibility belongs only to phenomena as observed by a restricted observer who must project all phenomena on a restricted subset of the set of all possible states. The possibility of a completely unrestricted observer who does not see irreversibility is discussed.