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Physics Today

What is ‘real’: A brief comparison

Karl David Stephan

Published Jun 1, 2008• 0 citations
Publisher

Abstract

Steven French’s review of Bernard d’Espagnat’s 500-page tome On Physics and Philosophy (Physics Today, Physics Today 0031-9228 60 6 2007 66 https://doi.org/10.1063/1.2754610. June 2007, page 66 ) got my attention, with its repeated discussion of something d’Espagnat calls “the Real.” I must confess I have not seen d’Espagnat’s book, but the more I read about this Real in French’s review, the more I thought I’d heard of it somewhere before. In the true scientific spirit of bringing to the attention of a researcher the results of prior research bearing on his work, I have interspersed citations from the Summa Theologica by Thomas Aquinas (1225–74) between passages from French’s review of d’Espagnat’s book.French states that the Real “nevertheless exerts an influence on the phenomena.”Aquinas wrote, “As there can be nothing which is not created by God, so there can be nothing which is not subject to His government” (part 1, question 103, article 5).French writes, “The grand laws of physics are ‘highly distorted reflections … of the great structures of “the Real”’ (page 455)…. The Real, although impossible to conceive, is nonseparable; from it, both consciousness and empirical reality ‘co-emerge.’”Aquinas wrote, “From the knowledge of sensible things the whole power of God cannot be known; nor therefore can His essence be seen. But because they are His effects and depend on their cause, we can be led from them so far as to know of God whether He exists, and to know of Him what must necessarily belong to Him, as the first cause of all things, exceeding all things caused by Him” (part 1, question 12, article 12).Aquinas maintained that there cannot ultimately be any disagreement between faith and reason because both come from an infinitely faithful and infinitely reasonable God. It is amusing that an apparently secular philosopher such as d’Espagnat, writing for a modern audience of physicists and philosophers and basing his thought on the latest results of quantum mechanics, has nevertheless arrived at conclusions in harmony with the greatest philosopher of the Middle Ages.© 2008 American Institute of Physics.

DOI
10.1063/1.2947632

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Steven French’s review of Bernard d’Espagnat’s 500-page tome On Physics and Philosophy (Physics Today, Physics Today 0031-9228 60 6 2007 66 https://doi.org/10.1063/1.2754610. June 2007, page 66 ) got my attention, with its repeated discussion of something d’Espagnat calls “the Real.” I must confess I have not seen d’Espagnat’s book, but the more I read about this Real in French’s review, the more I thought I’d heard of it somewhere before. In the true scientific spirit of bringing to the attention of a researcher the results of prior research bearing on his work, I have interspersed citations from the Summa Theologica by Thomas Aquinas (1225–74) between passages from French’s review of d’Espagnat’s book.French states that the Real “nevertheless exerts an influence on the phenomena.”Aquinas wrote, “As there can be nothing which is not created by God, so there can be nothing which is not subject to His government” (part 1, question 103, article 5).French writes, “The grand laws of physics are ‘highly distorted reflections … of the great structures of “the Real”’ (page 455)…. The Real, although impossible to conceive, is nonseparable; from it, both consciousness and empirical reality ‘co-emerge.’”Aquinas wrote, “From the knowledge of sensible things the whole power of God cannot be known; nor therefore can His essence be seen. But because they are His effects and depend on their cause, we can be led from them so far as to know of God whether He exists, and to know of Him what must necessarily belong to Him, as the first cause of all things, exceeding all things caused by Him” (part 1, question 12, article 12).Aquinas maintained that there cannot ultimately be any disagreement between faith and reason because both come from an infinitely faithful and infinitely reasonable God. It is amusing that an apparently secular philosopher such as d’Espagnat, writing for a modern audience of physicists and philosophers and basing his thought on the latest results of quantum mechanics, has nevertheless arrived at conclusions in harmony with the greatest philosopher of the Middle Ages.© 2008 American Institute of Physics.
Why is so shop-soiled a topic as scientific realism once again prominent in the philosophy of science? Realism fought a great battle when Copernican and Ptolemaic world views were at issue long ago. Towards the end of the nineteenth century worries about atomism strongly contributed to anti-realism among philosophers of science. Is there a comparable scientific issue today? Maybe. One way to understand quantum mechanics is to take an idealist line. Some people argue that human observation plays an integral role in the very nature of a physical system, so that the system changes simply when it is measured. Talk of ‘the measurement problem in quantum mechanics’, the ‘ignorance interpretation’, and ‘the collapse of the wave packet’ make it no accident that contributions to the philosophy of quantum mechanics play an important part in the writings of the more original figures in the realist debate. A number of the ideas of Hilary Putnam, Bas van Fraassen or Nancy Cartwright seem to result from taking quantum mechanics as the model of all science. Conversely, numerous physicists wax philosophical. Bernard d'Espagnat has made one of the most important recent contributions to a new realism. He is partly motivated by the dissolution, in some parts of modern physics, of old realist concepts such as matter and entity. He is especially driven by some recent results, that bear the general name of Bell's inequality, and which have been thought to call in question concepts as various as logic, the temporal order of causation, and action at a distance.
On several levels there is now a debate whether or not the concept of God can be made compatible with modern science. In an attempt to elucidate this debate, I give an account of my own experiences from writing a book on the foundation of quantum mechanics. It turns out that one can give two independent arguments for the existence of God by taking as departure an epistemic (knowledge-based) interpretation of quantum theory. Nevertheless I argue that any religious belief should be the result of an existential choice governed by each individual’s own context (history, personality, culture). My own faith is that God is greater than Christianity, and that Christianity is greater than the dogmas claimed by the Church.
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 .
ENERAL philosophy claims to be the critical subject which lays down for all of us what we may be allowed to think, and yet it has played no part whatever in the great revolutions of human thought of the present century-those connected with relativity and the quantum theory. It might have been expected that the scientists would have been constantly consulting the philosophers as to the legitimacy of their various speculations, but nothing of the kind has happened. Since no one can dispense with some sort of metaphysic, each scientist has made one for himself, and no doubt they contain many crudities, but it would seem that a deep interest in metaphysic is a disadvantage rather than an advantage to the physicist-at least I have the impression that those of my friends who are most inclined to speculate on the ultimate things appear to be the ones whose scientific work is most hampered by doing so. Now I propose to risk a similar indiscretion. I want to embody in it the practical philosophy of a physicist, and I do not mean it as an attack on the pure philosophers, who are very reasonable people, only chargeable with the minor offence of not having made me want to read their books! I had better begin by stating shortly the ideas I intend to discuss. There is a notable contrast between the way we think about things and the way we think we ought to think about them.
I am very grateful to the Master and Fellows of Trinity College for inviting me to give the Tarner Lectures. What I want to do in this book, stated boldly and baldly, is to consider the relevance of developments in modern theoretical physics to metaphysical questions about the ultimate nature of reality. By metaphysical questions I mean the very general sorts of questions that arise out of a critical examination of the principles, concepts and fundamental presuppositions that lie behind modern physics. How should we interpret the claims that physicists seem to be making about the world? Are they intended to be understood as literally true, for example, and exactly what are those claims, given that the pages of theoretical physics monographs are largely filled with abstract mathematical formalism? In the first chapter, I shall be looking at a range of philosophical points of view in the framework of which such questions can be addressed, and attempt the difficult task of adjudicating between the different approaches. At the end of the day I shall be arguing for a pretty straightforward metaphysical realism, that the external world exists independently of our knowledge of it. In the second chapter I shall look at arguments from various branches of modern physics that are sometimes claimed to bring in an essential role for subjectivity in physics, bringing the observer into a central role, creating his own reality.