Introduction It is a pleasure to be able to contribute to this volume in honour of Professor Michael Redhead. In the foundations of physics community, his influence has been felt both through his Incompleteness, Nonlocality and Realism (1987), which has largely denned the terms of discourse in this field for the last decade, and by the new ‘Cambridge School’ of the philosophy of physics that he established there during his Professorship in the History and Philosophy of Science Department. Michael Redhead's work illustrates well what has always seemed to be a central tenet of his: that philosophers of science should use the conceptual background and the mathematical formalism of modern, successful scientific theories – especially quantum mechanics and quantum field theory – as a guide to understanding the ontology of the world (Redhead 1983, 1990) and to reexamining traditional philosophical questions (French & Redhead 1988; Redhead & Teller 1991, 1992). In his Tarner Lectures (1995) he used this type of work to anchor a general position that can be characterized as structural realism , which holds that the structures – mathematical formalism, models, analogies – of a successful scientific theory eventually define the real, even as regards central, unobservable entities. While Professor Redhead has done an outstanding job of pressing forward with this general programme, it remains arguable that he and some of his co-workers, who have, in the main, stayed within the framework of standard quantum theory and relativity, may have effectively bracketed a different and potentially fruitful alternative theory.
Introduction It is a pleasure to be able to contribute to this volume in honour of Professor Michael Redhead. In the foundations of physics community, his influence has been felt both through his Incompleteness, Nonlocality and Realism (1987), which has largely denned the terms of discourse in this field for the last decade, and by the new ‘Cambridge School’ of the philosophy of physics that he established there during his Professorship in the History and Philosophy of Science Department. Michael Redhead's work illustrates well what has always seemed to be a central tenet of his: that philosophers of science should use the conceptual background and the mathematical formalism of modern, successful scientific theories – especially quantum mechanics and quantum field theory – as a guide to understanding the ontology of the world (Redhead 1983, 1990) and to reexamining traditional philosophical questions (French & Redhead 1988; Redhead & Teller 1991, 1992). In his Tarner Lectures (1995) he used this type of work to anchor a general position that can be characterized as structural realism , which holds that the structures – mathematical formalism, models, analogies – of a successful scientific theory eventually define the real, even as regards central, unobservable entities. While Professor Redhead has done an outstanding job of pressing forward with this general programme, it remains arguable that he and some of his co-workers, who have, in the main, stayed within the framework of standard quantum theory and relativity, may have effectively bracketed a different and potentially fruitful alternative theory.
The relation between Physics and Philosophy brings to mind the proverbial marriage of high drama; the parties do not approve of each other, but separated they cannot live. Philosophers find physicists shallow, and many physicists claim that they find philosophic speculations useless or worse. Mostly both display a lack of knowledge and understanding of the methods and goals of the other. A few researchers have tried to bridge this gap and explore the worlds of both parties. Michael Redhead has worked in this borderland, and when he retired from his chair in Cambridge, a symposium was arranged to honour him. The talks presented on this occasion are now published in a volume presenting much food for thought to both philosophers and physicists. The essays in this publication do not offer easy reading; not too many readers will have the preparation to penetrate the technical arguments offered. The authors are well acquainted with both philosophical argumentation and mathematical formalism, and, following the lead of Professor Redhead, they combine these in intricate and suggestive ways. Only a close reading can offer understanding of the points of view taken by the various authors. Browsing and mere reading defines the scenery, exploring it demands much more. Many of the nine essays included investigate the meaning of terms used loosely in physics contexts: locality, beables, symmetries and time in relativity. All essays utilize the mathematical structures of physics, but the approach is mainly philosophical; concepts like reality and metaphysics are applied. Some writings are more physical in their treatment of technical questions relating to modern quantum theory. Bohmian mechanics, localized quantum states and gauge symmetries are discussed in detail. It is, however, found that these present interpretational problems that are usually glossed over in purely physical treatments. For an old sceptic like myself, it is quite refreshing to find that many assertions, taken for granted in our textbooks, are indeed doubtful and offer conceptual or technical difficulties. This insight is what a philosophical analysis can offer the working physicist; future progress may well arise from such realizations. However, the results offered by philosophical analysis are usually found unsatisfactory; the hope that philosophy can suggest novel directions for the theory remains unfounded. Philosophers can learn that modern physics rests on a very shaky conceptual foundation. The theory has evolved by a combination of serendipity and opportunism. The beast that finally has emerged is neither well founded nor internally consistent. Its only merit is that it works. That offers the ultimate philosophical problem of modern physics. If the present book can help the philosopher to behold this challenging but overwhelming wilderness, then it serves a useful purpose indeed. But the prospective researcher has to learn to master the difficult language used by the natives, who are not always friendly. I enjoyed reading the book immensely, but the technical difficulty of the text made my understanding remain mostly superficial. I hope to have the time to return some of the essays, and look into the references and issues involved. The work is genuinely what it promises: a guide From Physics to Philosophy .
There are several (general) philosophy of physics textbooks on the market.1 An
obvious question to ask at the outset then is: Why another one? In his “Some
Philosophical Aspects of Particle Physics”, Michael Redhead bemoans the common practice of philosophers of science of dealing with examples “which are no
longer of current research interest in science” ((1980), p. 279). This practice is
still common even among many philosophers of physics, and, for the most part,
the available textbooks continue to engage in this practice. Generally, one finds a
little spacetime, a little statistical mechanics, and a little quantum theory. Now,
these are of course the ‘pillars’ of modern physics, so it is what we should expect
to be covered in any textbook on the philosophy of physics worth its salt (and,
indeed, they are well represented in this book). However, the issues that are
dealt with are usually very old fashioned and very limited in scope: ‘spacetime’
means ‘the twins paradox’ (and possibly conventionalism); ‘statistical mechanics’
means ‘time asymmetry’; and ‘quantum theory’ means ‘the measurement problem’. Redhead is surely right that this leads physicists to “regard philosophy of
science as somewhat irrelevant”. Rightly so, too, if this were in fact representative of much of what actually goes on in philosophy of physics. However, the
state of play as represented in philosophy of physics and (some) philosophy of
science journals shows a very different level of engagement, with philosophers
of physics investigating the frontiers of scientific research. This disparity (or the
impression of such) is the raison d’eˆtre for the book you are now reading. The result is an introductory textbook covering those portions of philosophy of physics
research that other textbooks fail to cover, or cover only very briefly or very
simplistically. The three pillars of modern physics-relativity, quantum theory
and statistical mechanics-are still represented, then, but from a more advanced
and contemporary perspective.
Classical mechanics and quantum mechanics are two of the most successful scientific theories ever discovered, and yet how they can describe the same world is far from clear: one theory is deterministic, the other indeterministic; one theory describes a world in which chaos is pervasive, the other a world in which chaos is absent. Focusing on the exciting field of 'quantum chaos', this book reveals that there is a subtle and complex relation between classical and quantum mechanics. It challenges the received view that classical and quantum mechanics are incommensurable, and revives another, largely forgotten tradition due to Niels Bohr and Paul Dirac. By artfully weaving together considerations from the history of science, philosophy of science, and contemporary physics, this book offers a new way of thinking about intertheory relations and scientific explanation. It will be of particular interest to historians and philosophers of science, philosophically-inclined physicists, and interested non-specialists.
Classical mechanics and quantum mechanics are two of the most successful scientific theories ever discovered, and yet how they can describe the same world is far from clear: one theory is deterministic, the other indeterministic; one theory describes a world in which chaos is pervasive, the other a world in which chaos is absent. Focusing on the exciting field of 'quantum chaos', this book reveals that there is a subtle and complex relation between classical and quantum mechanics. It challenges the received view that classical and quantum mechanics are incommensurable, and revives another, largely forgotten tradition due to Niels Bohr and Paul Dirac. By artfully weaving together considerations from the history of science, philosophy of science, and contemporary physics, this book offers a new way of thinking about intertheory relations and scientific explanation. It will be of particular interest to historians and philosophers of science, philosophically-inclined physicists, and interested non-specialists.
This is the first volume that focuses specifically on phenomenological approaches to quantum mechanics. It is also the first volume focusing on the philosophical implications of QBism. This coincidence is not accidental. Phenomenology's rich potential for our understanding of quantum mechanics has long been overlooked by analytic philosophers and phenomenologists alike. The experience-first approach of phenomenology, its descriptive methodology, and Husserl's critique of mathematization do not sit well with “mainstream” analytic philosophy of physics. But as this volume will demonstrate, it sits nicely with the basic tenets of QBism. Conversely, QBism constitutes the most consistent and best-developed interpretation of quantum mechanics that fully embraces the Bohrian idea that a proper understanding of science must be based on the concept of experience. However, since its inception in the early 2000s, QBism has struggled to connect with the philosophical community. Not only are the underlying intuitions shaping and dominating contemporary philosophy of quantum mechanics—namely, that a scientific theory must be purged of all subjective and operational notions such as “experience” or “measurement” and that, consequently, a successful approach to quantum mechanics must be formulated as a “quantum theory without observers”—at odds with QBism. It seems that sometimes the incommensurability already starts at the level of the basic conceptual framework which, in the case of mainstream analytic philosophy, is not very well suited to express some of QBism's main tenets. Considering this situation, the main hypothesis of this volume is that phenomenology and QBism are natural bedfellows, and that both can profit from mutual exchange. In order to make this exchange as profitable as possible, the aim of this introductory chapter is to identify, clarify, and motivate some of the cornerstones of phenomenological approaches to quantum mechanics, to shed light on the main ideas and virtues of QBism, and to discuss points of contact and points of possible conflict between these two projects.
This novel text directly addresses common claims and misconceptions around quantum mechanics and presents a fresh and modern understanding of this fundamental and essential physical theory. It begins with a non-mathematical introduction to some of the more controversial topics in the foundations of quantum mechanics. For those more familiar with the theoretical framework of quantum mechanics, the text moves on to a general introduction to quantum field theory, followed by a detailed discussion of cutting-edge topics in this area such as decoherence and spontaneous coherence. Several important philosophical problems in quantum mechanics are considered, and their interpretations are compared, notably the Copenhagen and many-worlds interpretations. The inclusion of frequent real-world examples, such as superconductors and superfluids, ensures the book remains grounded in modern research. This book will be a valuable resource for students and researchers in both physics and the philosophy of science interested in the foundations of quantum mechanics.