A sophisticated and original introduction to the philosophy of quantum mechanics from one of the world’s leading philosophers of physics In this book, Tim Maudlin, one of the world’s leading philosophers of physics, offers a sophisticated, original introduction to the philosophy of quantum mechanics. The briefest, clearest, and most refined account of his influential approach to the subject, the book will be invaluable to all students of philosophy and physics. Quantum mechanics holds a unique (...) place in the history of physics. It has produced the most accurate predictions of any scientific theory, but, more astonishing, there has never been any agreement about what the theory implies about physical reality. Maudlin argues that the very term “quantum theory” is a misnomer. A proper physical theory should clearly describe what is there and what it does—yet standard textbooks present quantum mechanics as a predictive recipe in search of a physical theory. In contrast, Maudlin explores three proper theories that recover the quantum predictions: the indeterministic wavefunction collapse theory of Ghirardi, Rimini, and Weber; the deterministic particle theory of deBroglie and Bohm; and the conceptually challenging Many Worlds theory of Everett. Each offers a radically different proposal for the nature of physical reality, but Maudlin shows that none of them are what they are generally taken to be. (shrink)

This book is a critical introduction to the long-standing debate concerning the conceptual foundations of quantum mechanics and the problems it has posed for physicists and philosophers from Einstein to the present. Quantum theory has been a major infulence on postmodernism, and presents significant problems for realists. Keeping his own realist position in check, Christopher Norris subjects a wide range of key opponents and supporters of realism to a high and equal level of scrutiny. With a characteristic (...) combination of rigour and intellectual generosity, he draws out the merits and weaknesses from opposing arguments. In a sequence of closely argued chapters, Norris examines the premises of orthodox quantum theory, as developed most influentially by Bohr and Heisenberg, and its impact on varous philosophical developments. These include the ideas developed by W.V Quine, Thomas Kuhn, Michael Dummett, Bas van Fraassen, and Hilary Puttnam. In each case, Norris argues, these thinkers have been influenced by the orthodox construal of quantum mechanics as requiring drastic revision of principles which had hitherto defined the very nature of scientific method, causal explanati and rational enquiry. Putting the case for a realist approach which adheres to well-tried scientific principles of causal reasoning and inference to the best explanation, Christopher Norris clarifies these debates to a non-specialist readership and scholars of philosophy, science studies and the philosophy of science alike. Quantum Theory and the Flight From Realism suggests that philosophical reflection can contribute to a better understanding of these crucial, current issues. (shrink)

Quantum Theory and the Schism in Physics is one of the three volumes of Karl Popper’s Postscript to the Logic of scientific Discovery . The Postscript is the culmination of Popper’s work in the philosophy of physics and a new famous attack on subjectivist approaches to philosophy of science. Quantum Theory and the Schism in Physics is the third volume of the Postscript . It may be read independently, but it also forms part of (...) Popper’s interconnected argument in the Postscript . It presents Popper’s classic statement on quantum physics and offers important insights into his thinking on problems of method within science and physics as a whole. (shrink)

The basic theme of Popper's philosophy--that something can come from nothing--is related to the present situation in physical theory. Popper carries his investigation right to the center of current debate in quantum physics. He proposes an interpretation of physics--and indeed an entire cosmology--which is realist, conjectural, deductivist and objectivist, anti-positivist, and anti-instrumentalist. He stresses understanding, reminding us that our ignorance grows faster than our conjectural knowledge.

The 1927 Solvay conference was perhaps the most important meeting in the history of quantum theory. Contrary to popular belief, the interpretation of quantum theory was not settled at this conference, and no consensus was reached. Instead, a range of sharply conflicting views were presented and extensively discussed, including de Broglie's pilot-wave theory, Born and Heisenberg's quantum mechanics, and Schrödinger's wave mechanics. Today, there is no longer an established or dominant interpretation of quantum (...) theory, so it is important to re-evaluate the historical sources and keep the interpretation debate open. This book contains a complete translation of the original proceedings, with background essays on the three main interpretations of quantum theory presented at the conference, and an extensive analysis of the lectures and discussions in the light of current research in the foundations of quantum theory. The proceedings contain much unexpected material, including extensive discussions of de Broglie's pilot-wave theory (which de Broglie presented for a many-body system), and a theory of 'quantum mechanics' apparently lacking in wave function collapse or fundamental time evolution. This book will be of interest to graduate students and researchers in physics and in the history and philosophy of quantum theory. (shrink)

Philosophers of quantum mechanics have generally addressed exceedingly simple systems. Laura Ruetsche offers a much-needed study of the interpretation of more complicated systems, and an underexplored family of physical theories, such as quantum field theory and quantum statistical mechanics, showing why they repay philosophical attention. She guides those familiar with the philosophy of ordinary QM into the philosophy of 'QM infinity', by presenting accessible introductions to relevant technical notions and the foundational questions they frame--and (...) then develops and defends answers to some of those questions. Finally, Ruetsche highlights ties between the foundational investigation of QM infinity and philosophy more broadly construed, in particular by using the interpretive problems discussed to motivate new ways to think about the nature of physical possibility and the problem of scientific realism. (shrink)

Is it possible to approach quantum theory in a 'therapeutic' vein that sees its foundational problems as arising from mistaken conceptual presuppositions? The book explores the prospects for this project and, in doing so, discusses such fascinating issues as the nature of quantum states, explanation in quantum theory, and 'quantum non-locality'.

_Quantum Theory and the Schism in Physics_ is one of the three volumes of Karl Popper’s _Postscript to the Logic of scientific Discovery_. The_ Postscript_ is the culmination of Popper’s work in the philosophy of physics and a new famous attack on subjectivist approaches to philosophy of science. Quantum Theory and the Schism in Physics is the third volume of the _Postscript_. It may be read independently, but it also forms part of Popper’s interconnected argument (...) in the _Postscript_. It presents Popper’s classic statement on quantum physics and offers important insights into his thinking on problems of method within science and physics as a whole. (shrink)

I offer an account of how the quantum theory we have helps us explain so much. The account depends on a pragmatist interpretation of the theory: this takes a quantum state to serve as a source of sound advice to physically situated agents on the content and appropriate degree of belief about matters concerning which they are currently inevitably ignorant. The general account of how to use quantum states and probabilities to explain otherwise puzzling regularities (...) is then illustrated by showing how we can explain single-particle interference phenomena, the stability of matter, and interference of Bose–Einstein condensates. Finally, I note some open problems and relate this account to alternative approaches to explanation that emphasize the importance of causation, of unification, and of structure. 1 Introduction2 Two Requirements on Explanations in Physics3 What We Can use Quantum Theory to Explain4 The Function of Quantum States and Born Probabilities5 How These Functions Contribute to the Explanatory Task6 Example One: Single-Particle Interference7 Example Two: Explanation of the Stability of Matter8 Example Three: Bose Condensation9 Conclusion. (shrink)

David Wallace argues that we should take quantum theory seriously as an account of what the world is like--which means accepting the idea that the universe is constantly branching into new universes. He presents an accessible but rigorous account of the 'Everett interpretation', the best way to make coherent sense of quantum physics.

I give an introduction to the conceptual structure of quantum field theory as it is used in mainstream theoretical physics today, aimed at non-specialists. My main focuses in the article are the common structure of quantum field theory as it is applied in solid-state physics and as it is applied in high-energy physics; the modern theory of renormalisation.

I offer an account of how the quantum theory we have helps us explain the enormous variety of phenomena it is generally taken to explain. The account depends on what I have elsewhere called a pragmatist interpretation of the theory. This rejects views according to which a quantum state describes or represents a physical system, holding instead that it functions as a source of sound advice to physically situated agents like us on the content and appropriate (...) degree of belief about matters concerning which they are currently inevitably ignorant. So while the account given here is incompatible with some views of structural explanation in quantum theory it is nevertheless able to incorporate what I take to be their valuable insights. (shrink)

From the beginning, the implications of quantum theory for our most general understanding of the world have been a matter of intense debate. Einstein argues that the theory had to be regarded as fundamentally incomplete. Its inability, for example, to predict the exact time of decay of a single radioactive atom had to be due to a failure of the theory and not due to a permanent inability on our part or a fundamental indeterminism in nature (...) itself. In 1964, John Bell derived a theorem which showed that any deterministic theory which preserved locality would have certain consequences for measurements performed at a distance from one another. An experimental check seems to show that these consequences are not, in fact, realized. The correlation between the sets of events is much stronger than any local deterministic theory could allow. What is more, this stronger correlation is precisely that which is predicted by quantum theory. The astonishing result is that local deterministic theories of the classical sort seem to be permanently excluded. Not only can the individual decay not be predicted, but no future theory can ever predict it. The contributors in this volume wrestle with this conclusion. Some welcome it; others leave open a return to at lease some kind of deterministic world, one which must however allow something like action-at-a distance. How much lit it? And how can one avoid violating relativity theory, which excludes action-at-a-distance? How can a clash between the two fundamental theories of modern physics, relativity and quantum theory, be avoided? What are the consequences for the traditional philosophic issue of causality explanation and objectivity? One thing is certain; we can never return to the comfortable Newtonian world where everything that happened was, in principle, predictable and where what happened at one measurement site could not affect another set of measurements being performed light-years away, at a distance that a light-signal could not bridge. Contributors: James T. Cushing, Abner Shimony, N. David Mermin, Jon P. Jarrett, Linda Wessels, Bas C. van Fraassen, Jeremy Butterfield, Michael L. G. Redhead, Henry P. Stapp, Arthur Fine, R. I. G. Hughes, Paul Teller, Don Howard, Henry J. Folse, and Ernan McMullin. (shrink)

In his recent book Bananaworld. Quantum mechanics for primates, Jeff Bub revives and provides a mature version of his influential information-theoretic interpretation of Quantum Theory (QT). In this paper, I test Bub’s conjecture that QT should be interpreted as a theory about information, by examining whether his information-theoretic interpretation has the resources to explain (or explain away) quantum conundrums. The discussion of Bub’s theses will also serve to investigate, more in general, whether other approaches succeed (...) in defending the claim that QT is about quantum information. First of all, I argue that Bub’s interpretation of QT as a principle theory fails to fully explain quantum non-locality. Secondly, I argue that a constructive interpretation, where the quantum state is interpreted ontically as information, also fails at providing a full explanation of quantum correlations. Finally, while epistemic interpretations might succeed in this respect, I argue that such a success comes at the price of rejecting some in between the most basic scientific standards of physical theories. (shrink)

What would it mean to apply quantum theory, without restriction and without involving any notion of measurement and state reduction, to the whole universe? What would realism about the quantum state then imply? This book brings together an illustrious team of philosophers and physicists to debate these questions. The contributors broadly agree on the need, or aspiration, for a realist theory that unites micro- and macro-worlds. But they disagree on what this implies. Some argue that if (...) unitary quantum evolution has unrestricted application, and if the quantum state is taken to be something physically real, then this universe emerges from the quantum state as one of countless others, constantly branching in time, all of which are real. The result, they argue, is many worlds quantum theory, also known as the Everett interpretation of quantum mechanics. No other realist interpretation of unitary quantum theory has ever been found. Others argue in reply that this picture of many worlds is in no sense inherent to quantum theory, or fails to make physical sense, or is scientifically inadequate. The stuff of these worlds, what they are made of, is never adequately explained, nor are the worlds precisely defined; ordinary ideas about time and identity over time are compromised; no satisfactory role or substitute for probability can be found in many worlds theories; they can't explain experimental data; anyway, there are attractive realist alternatives to many worlds. Twenty original essays, accompanied by commentaries and discussions, examine these claims and counterclaims in depth. They consider questions of ontology - the existence of worlds; probability - whether and how probability can be related to the branching structure of the quantum state; alternatives to many worlds - whether there are one-world realist interpretations of quantum theory that leave quantum dynamics unchanged; and open questions even given many worlds, including the multiverse concept as it has arisen elsewhere in modern cosmology. A comprehensive introduction lays out the main arguments of the book, which provides a state-of-the-art guide to many worlds quantum theory and its problems. (shrink)

Quantum theory is one the most important and successful theories of modern physical science. It has been estimated that its principles form the basis for about 30 per cent of the world's manufacturing economy. This is all the more remarkable because quantum theory is a theory that nobody understands. The meaning of Quantum Theory introduces science students to the theory's fundamental conceptual and philosophical problems, and the basis of its non-understandability. It does (...) this with the barest minimum of jargon and very little mathematics in the main text. Readers wishing to delve more deeply into the theory's mathematical subtleties can do so in an extended series of appendices. The book brings the reader up to date with the results of new experimental tests of quantum weirdness and reviews the latest thinking on alternative interpretations, the frontiers of quantum cosmology, quantum gravity and potential application of this weirdness in computing, cryptography and teleportation. (shrink)

The received view in physicalist philosophy of mind assumes that causation can only take place at the physical domain and that the physical domain is causally closed. It is often thought that this leaves no room for mental states qua mental to have a causal influence upon the physical domain, leading to epiphenomenalism and the problem of mental causation. However, in recent philosophy of causation there has been growing interest in a line of thought that can be called (...) causal antifundamentalism: causal notions cannot play a role in physics, because the fundamental laws of physics are radically different from causal laws. Causal anti-fundamentalism seems to challenge the received view in physicalist philosophy of mind and thus raises the possibility of there being genuine mental causation after all. This paper argues that while causal anti-fundamentalism provides a possible route to mental causation, we have reasons to think that it is incorrect. Does this mean that we have to accept the received view and give up the hope of genuine mental causation? I will suggest that the ontological interpretation of quantum theory provides us both with a view about the nature of causality in fundamental physics, as well as a view how genuine mental causation can be compatible with our fundamental (quantum) physical ontology. (shrink)

While its applications have made quantum theory arguably the most successful theory in physics, its interpretation continues to be the subject of lively debate within the community of physicists and philosophers concerned with conceptual foundations. This situation poses a problem for a pragmatist for whom meaning derives from use. While disputes about how to use quantum theory have arisen from time to time, they have typically been quickly resolved, and consensus reached, within the relevant scientific (...) sub-community. Yet rival accounts of the meaning of quantum theory continue to proliferate . In this article I offer a diagnosis of this situation and outline a pragmatist solution to the problem it poses, leaving further details for subsequent articles. (shrink)

In the Critique of Pure Reason Kant argues that the empirical knowledge of the world depends on a priori conditions of human sensibility and understanding, i. e., our capacities of sense experience and concept formation. The objective knowledge presupposes, on one hand, space and time as a priori conditions of sensibility and, on another hand, a priori judgments, like the principle of causality, as constitutive conditions of understanding. The problem is that in the XX century the physical science completely changed (...) how we conceive our knowledge of the world. Face to this new situation, what was changed in our classical reason? However, if the transcendental point of view is adopted, in the specific case of quantum mechanics, we have to wonder about the general conditions of this theory that make possible such knowledge, which predictive value is much more accurate than the classical physics. The aim of this work is firstly to show the Kantian implications on Bohr’s interpretation of quantum phenomena and secondly to provide an overview of the key elements for understanding the transcendental locus of ordinary language in the quantum mechanics context, in order to give support to a transcendental pragmatic position in the analysis of science. (shrink)

Two successes of old quantum theory are particularly notable: Bohr’s prediction of the spectral lines of ionised helium, and Sommerfeld’s prediction of the fine-structure of the hydrogen spectral lines. Many scientific realists would like to be able to explain these successes in terms of the truth or approximate truth of the assumptions which fuelled the relevant derivations. In this paper I argue that this will be difficult for the ionised helium success, and is almost certainly impossible for the (...) fine-structure success. Thus I submit that the case against the realist’s thesis that success is indicative of truth is marginally strengthened. (shrink)

Nobel Laureate in physics Wolfgang Pauli studied philosophy and the history of ideas intensively, especially in his later years, to form an accurate ontology vis-à-vis quantum theory. Pauli's close contacts with the Swiss psychiatrist C.G. Jung gave him special qualifications for also understanding the basic problems of empirical knowledge. After Pauli's sudden death in 1958, this work was maintained mainly in his posthumously published correspondence, which so far extends only to 1939. Because Pauli's view differs essentially from (...) the direction physics research took after the deaths of the founding fathers of quantum theory, this article attempts to describe the main features in Pauli's revolutionary thought, which is based on nature's “epistemological lesson” as revealed by Pauli's atomic research. Pauli's conclusions have important implications for various issues in Western culture, not least with the limits of science and the relation of science to religion. (shrink)

In this paper I defend the claim that quantum theory, Specifically quantum field theory (qft), Is incompatible with leibniz's principle of the identity of indiscernibles. This is in response to r. Barnette's criticism ("philosophy of science" 45:466-470) of an argument given by alberto cortes ("philosophy of science" 43:491-505) intended to establish this claim. I show that, Using the qft point of view, Cortes' argument can be restated in a way that leaves it immune to (...) barnette's criticism. (shrink)

Empirical adequacy, formal explanation and understanding are distinct goals of science. While no a priori criterion for understanding should be laid down, there may be inherent limitations on the way we are able to understand explanations of physical phenomena. I examine several recent contributions to the exercise of fashioning an explanatory discourse to mold the formal explanation provided by quantum mechanics to our modes of understanding. The question is whether we are capable of truly understanding (or comprehending) quantum (...) phenomena, as opposed to simply accepting the formalism and certain irreducible quantum correlations. The central issue is that of understanding versus merely redefining terms to paper over our ignorance. (shrink)

We are often told that quantum phenomena demand radical revisions of our scientific world view and that no physical theory describing well defined objects, such as particles described by their positions, evolving in a well defined way, let alone deterministically, can account for such phenomena. The great majority of physicists continue to subscribe to this view, despite the fact that just such a deterministic theory, accounting for all of the phe nomena of nonrelativistic quantum mechanics, was (...) proposed by David Bohm more than four decades ago and has arguably been around almost since the inception of quantum mechanics itself. Our purpose in asking colleagues to write the essays for this volume has not been to produce a Festschrift in honor of David Bohm or to gather together a collection of papers simply stating uncritically Bohm's views on quantum mechanics. The central theme around which the essays in this volume are arranged is David Bohm's version of quantum mechanics. It has by now become fairly standard practice to refer to his theory as Bohmian mechanics and to the larger conceptual framework within which this is located as the causal quantum theory program. While it is true that one can have reservations about the appropriateness of these specific labels, both do elicit distinc tive images characteristic of the key concepts of these approaches and such terminology does serve effectively to contrast this class of theories with more standard formulations of quantum theory. (shrink)

In this new edition, Arthur Fine looks at Einstein's philosophy of science and develops his own views on realism. A new Afterword discusses the reaction to Fine's own theory. "What really led Einstein . . . to renounce the new quantum order? For those interested in this question, this book is compulsory reading."--Harvey R. Brown, American Journal of Physics "Fine has successfully combined a historical account of Einstein's philosophical views on quantum mechanics and a discussion of (...) some of the philosophical problems associated with the interpretation of quantum theory with a discussion of some of the contemporary questions concerning realism and antirealism. . . . Clear, thoughtful, [and] well-written."--Allan Franklin, Annals of Science "Attempts, from Einstein's published works and unpublished correspondence, to piece together a coherent picture of 'Einstein realism.' Especially illuminating are the letters between Einstein and fellow realist Schrodinger, as the latter was composing his famous 'Schrodinger-Cat' paper."--Nick Herbert, New Scientist "Beautifully clear. . . . Fine's analysis is penetrating, his own results original and important. . . . The book is a splendid combination of new ways to think about quantum mechanics, about realism, and about Einstein's views of both."--Nancy Cartwright, Isis. (shrink)

This book explains, in simple but accurate terms, how orthodox quantum mechanics works. The author, a distinguished theoretical physicist, shows how this theory, realistically interpreted, assigns an important role to our conscious free choices. Stapp claims that mainstream biology and neuroscience, despite nearly a century of quantum physics, still stick essentially to failed classical precepts in which mental intentions have no effect upon our bodily actions. He shows how quantum mechanics provides a rational basis for a (...) better understanding of this connection, even allowing an explanation of certain phenomena currently held to be "paranormal". These ideas have major implications for our understanding of ourselves and our mental processes, and thus also for the meaningfulness of our lives. (shrink)

_Quantum Theory and the Schism in Physics_ is one of the three volumes of Karl Popper’s _Postscript to the Logic of scientific Discovery_. The_ Postscript_ is the culmination of Popper’s work in the philosophy of physics and a new famous attack on subjectivist approaches to philosophy of science. Quantum Theory and the Schism in Physics is the third volume of the _Postscript_. It may be read independently, but it also forms part of Popper’s interconnected argument (...) in the _Postscript_. It presents Popper’s classic statement on quantum physics and offers important insights into his thinking on problems of method within science and physics as a whole. (shrink)

_Quantum Theory and the Schism in Physics_ is one of the three volumes of Karl Popper’s _Postscript to the Logic of scientific Discovery_. The_ Postscript_ is the culmination of Popper’s work in the philosophy of physics and a new famous attack on subjectivist approaches to philosophy of science. Quantum Theory and the Schism in Physics is the third volume of the _Postscript_. It may be read independently, but it also forms part of Popper’s interconnected argument (...) in the _Postscript_. It presents Popper’s classic statement on quantum physics and offers important insights into his thinking on problems of method within science and physics as a whole. (shrink)

The aim of science is the explanation of complicated systems by reducing it to simple subsystems. According to a millennia-old imagination this will be attained by dividing matter into smaller and smaller pieces of it. The popular superstition that smallness implies simplicity seems to be ineradicable. However, since the beginning of quantum theory it would be possible to realize that the circumstances in nature are exactly the other way round. The idea “smaller becomes simpler” is useful only down (...) to the atoms of chemistry. Planck’s formula shows that smaller extensions are related to larger energies. That more and more energy should result in simpler and simpler structures, this does not only sound absurd, it is absurd. A reduction to really simple structures leads one to smallest energies and, thus, to utmost extended quantum systems. The simplest quantum structure, referred to as quantum bit, has a two-dimensional state space, and it establishes a cosmological structure. Taking many of such quantum bits allows also for the construction of localized particles. The non-localized fraction of quantum bits can appear as “dark matter”. (shrink)

This chapter contains sections titled: Introduction: Interpretation Bohr and Complementarity The Einstein‐Podolsky‐Rosen (EPR) Argument Bell's Theorem and Other No‐Go Results The Measurement Problem Future Directions: Interpreting QFT.

J. Baird Callicott seeks to resolve the problem of the intrinsic value of nature by utilizing a nondualistic paradigm derived from quantum theory. His approach is twofold. According to his less radical approach, quantum theory shows that properties once considered to be “primary” and “objective” are in fact the products of interactions between observer and observed. Values are also the products of such interactions. According to his more radical approach, quantum theory’s doctrine of internal (...) relations is the model for the idea that everything is intrinsically valuable because the “I” is intrinsically valuable and related to everything else. I argue that humanity’s treatment of nature will become respectful only as humanity’s awareness evolves toward nondualism, and that such nondualistic awareness will not be produced by changes in scientific theory alone. Nevertheless, as Callicott suggests, such changes may be harbingers of evolutionary trends in human awareness. I conclude with a sketch of how nondualism, especially in its panentheistic version, provides the basis for environmental ethics. (shrink)

Quantum theory launched a revolution in physics. But we have yet to understand the revolution's significance for philosophy. Richard Healey opens a path to such understanding. The first part of this book offers a self-contained but opinionated introduction to quantum theory. The second part assesses the theory's philosophical significance.

Interpretations, or generalizations, of quantum theory that are applicable to cosmology are of interest because they must display and resolve the "paradoxes" directly. The Everett interpretation is reexamined and compared with two alternatives. Its "metaphysical" connotations can be removed, after which it is found to be more acceptable than a theory which incorporates collapse, while retaining some unsatisfactory features.

​This book summarizes the results of research the authors have pursued in the past years on the problem of implementing Bell's notion of local causality in local physical theories and relating it to other important concepts and principles in the foundations of physics such as the Common Cause Principle, Bell's inequalities, the EPR scenario, and various other locality and causality concepts. The book is intended for philosophers of science with an interest in the formal background of sciences, philosophers of physics (...) and physicists working in foundation of physics. (shrink)

J. Baird Callicott seeks to resolve the problem of the intrinsic value of nature by utilizing a nondualistic paradigm derived from quantum theory. His approach is twofold. According to his less radical approach, quantum theory shows that properties once considered to be “primary” and “objective” are in fact the products of interactions between observer and observed. Values are also the products of such interactions. According to his more radical approach, quantum theory’s doctrine of internal (...) relations is the model for the idea that everything is intrinsically valuable because the “I” is intrinsically valuable and related to everything else. I argue that humanity’s treatment of nature will become respectful only as humanity’s awareness evolves toward nondualism, and that such nondualistic awareness will not be produced by changes in scientific theory alone. Nevertheless, as Callicott suggests, such changes may be harbingers of evolutionary trends in human awareness. I conclude with a sketch of how nondualism, especially in its panentheistic version, provides the basis for environmental ethics. (shrink)

Quantum Theory, similar to Relativity Theory, requires a new concept of space-time, imposed by a universal constant. While velocity of lightcnot being infinite calls for a redefinition of space-time on large and cosmological scales, quantization of action in terms of a finite, i.e. non vanishing, universal constanthrequires a redefinition of space-time on very small scales. Most importantly, the classical notion of “time”, as one common continuous time variable and nature evolving continuously “in time”, has to be replaced (...) by an infinite manifold of transition rates for discontinuous quantum transitions. The fundamental laws of quantum physics, commutation relations and quantum equations of motion, resulted from Max Born’s recognition of the basic principle of quantum physics:To each change in nature corresponds an integer number of quanta of action. Action variables may only change by integer values ofh, requiring all other physical quantities to change by discrete steps, “quantum jumps”. The mathematical implementation of this principle led to commutation relations and quantum equations of motion. The notion of “point” in space-time looses its physical significance; quantum uncertainties of time, position, just as any other physical quantity, are necessary consequences of quantization of action. (shrink)

To mathematicians, mathematics is a happy game, to scientists a mere tool and to philosophers a Platonic mystery - or so the caricature runs. The caricature reflects the alleged 'cultural gap' between the disciplines a gap for which there too often has been, sadly, sound historical evidence. In many minds the lack of communication between philosophy and the exact disciplines is especially prominent. Yet in the past there was no separation - exact knowledge, covering both scientists and mathemati cians, (...) was known as natural philosophy and the business of providing a critical view of the nature of reality and an accurate mathematical de scription of it constituted a single task from the glorious tradition begun by the early Greek philosophers even up until Newton's day (but I am thinking of Descartes and Leibniz I). The lack of communication between these professional groups has been particularly unfortunate, for the past half century has seen the most ex citing developments in mathematical physics since Newton. These devel opments hinged on the introduction of vast new reaches of mathematics into physics (non-Euclidean geometries, covariant formulations, non commutative algebras, functional analysis and so on) and conversely have challenged mathematicians to develop the appropriate mathematical fields. Equally, these developments have posed profound philosophical problems to do with the rejection of traditional conceptions concerning the nature of physical reality and physical theorising. (shrink)

The paper compares ontic structural realism in quantum physics with ontic structural realism about space–time. We contend that both quantum theory and general relativity theory support a common, contentful metaphysics of ontic structural realism. After recalling the main claim of ontic structural realism and its physical support, we point out that both in the domain of quantum theory and in the domain of general relativity theory, there are objects whose essential ways of being (...) are certain relations so that these objects do not possess an intrinsic identity. Nonetheless, the qualitative, physical nature of these relations is in the quantum case (entanglement) fundamentally different from the classical, metrical relations treated in general relativity theory. (shrink)

Probably the most successful scientific theory ever created, quantum theory has profoundly changed our view of the world and extended the limits of our knowledge, impacting both the theoretical interpretation of a tremendous range of phenomena and the practical development of a host of technological breakthroughs. Yet for all its success, quantum theory remains utterly baffling. Quantum Reality: Theory and Philosophy cuts through much of the confusion to provide readers with an exploration (...) of quantum theory that is as authoritatively comprehensive as it is intriguingly comprehensible. Requiring no more than school level physics and mathematics background, this volume requires only an interest in understanding how quantum theory came to be and the myriad ways it both explains how our universe functions and extends the reach of human knowledge. Written by well-known physics author and teacher Dr. Jonathan Allday, this highly engaging work: Presents a thorough grounding in the theoretical machinery of quantum physics Offers a whistle-stop tour through the early part of the 20th century when the founding fathers of quantum theory forever altered the frontiers of human thought Provides an example-filled interpretation of the theory, its applications, and its pinnacle in quantum field theory (QFT), so crucial in shaping ideas about the nature of reality Separates fact from speculation regarding quantum physics’ ability to provide a starting point for philosophical queries into ultimate understanding and the limits of science The world beneath the one that we experience with our senses is profoundly mysterious, and while we may never completely unravel that mystery, quantum theory allows us to come closer than ever to understanding where the science leaves off and the mystery begins. Quantum Reality: Theory and Philosophy makes that understanding accessible to anyone possessing a quest for knowledge and a sense of awe. (shrink)

Many have suggested that the transformation standardly referred to as `time reversal' in quantum theory is not deserving of the name. I argue on the contrary that the standard definition is perfectly appropriate, and is indeed forced by basic considerations about the nature of time in the quantum formalism.