This book examines in detail two of the fundamental questions raised by quantum mechanics. First, is the world indeterministic? Second, are there connections between spatially separated objects? In the first part, the author examines several interpretations, focusing on how each proposes to solve the measurement problem and on how each treats probability. In the second part, the relationship between probability (specifically determinism and indeterminism) and non-locality is examined, and it is argued that there is a non-trivial relationship between probability and (...) non-locality. The author then re-examines some of the interpretations of part one of the book in the light of this argument, and considers how they fare with regard to locality and Lorentz invariance. The book will appeal to anyone with an interest in the interpretation of quantum mechanics, including researchers in the philosophy of physics and theoretical physics, as well as graduate students in those fields. (shrink)

In the The Undivided Universe, David Bohn and Basil Hiley present a radically different approach to quantum theory.

Classical physics is about real objects, like apples falling from trees, whose motion is governed by Newtonian laws. In standard quantum mechanics only the wave function 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? (shrink)

By questioning the validity of some of our basic concepts, such as space, object, and causality, quantum physics contributes quite decisively to the dramatic changes now taking place in our world picture. Veiled Reality provides a detailed view of the reasons why such a questioning arises, a survey of the corresponding conceptual and theoretical problems, and a comprehensive, up-to-date account, useful to scientists and epistemologists alike, of the various ways present-day physicists tackle these problems.The book deals with the E.P.R. reality (...) criterion, local causality, and quantum measurement including relativistic quantum collapse, decoherence theories, consistent histories approaches, and ontologically interpretable theories. Questions bearing on the connection between counterfactuality and realism, intersubjective agreement, and limits of the bearing of the verbs “to have” and “to be,” follow naturally from the analysis and are thoroughly examined. Finally, distinguishing between empirical reality and a veiled independent reality whose only knowable features are structural yields a clue to a plausible interpretation of current physics.Accessible to readers with only very elementary background in modern physics, Veiled Reality offers nonspecialists, including students in physics and philosophy, easy access to basic problems in the foundation of physics. (shrink)

The role of the environment in producing the correct classical limit in the Bohm interpretation of quantum mechanics is investigated, in the context of a model of quantum Brownian motion. One of the effects of the interaction is to produce a rapid approximate diagonalisation of the reduced density matrix in the position representation. This effect is, by itself, insufficient to produce generically quasi-classical behaviour of the Bohmian trajectory. However, it is shown that, if the system particle is initially in an (...) approximate energy eigenstate, then there is a tendency for the Bohmian trajectory to become approximately classical on a longer time-scale. The relationship between this phenomenon and the behaviour of the Wigner function post-decoherence is discussed. (shrink)

The generic Bohmian trajectories are calculated for an isolated particle in an approximate energy eigenstate, for an arbitrary one-dimensional potential well. It is shown that the necessary and sufficient condition for there to be a negligible probability of the trajectory deviating significantly from the classical trajectory at any stage in the motion is that the state be a narrowly localised wave packet. The properties of the Bohmian trajectories are compared with those in the interpretation recently proposed by García de Polavieja. (...) The reasons why the latter tend to be much more nearly classical are discussed. The implications for other trajectory interpretations are considered. (shrink)

This fascinating work goes beyond the standard interpretation of quantum theory to explore its fundamental concepts. Author Dipankar Home examines such alternative schemes as the Bohmian approach, the decoherence models, and the dynamical models of wave function collapse. Home carefully explains how a number of the anomalies in quantum theory have become amenable to precise quantitative formulations Throughout the chapters, the emphasis is on conceptual aspects of quantum theory and the implications of recent investigations into these questions.