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Glimpsing Reality:

Ideas in Physics and the Link to Biology

Edited by Paul Buckley and F. David Peat

Twenty years ago Paul Buckley and F. David Peat asked several physicists, biologists, and chemists who had been involved in some of the most exciting discoveries in modern scientific thought to participate in the interviews that formed the heart of the book *A Question of Physics: Conversations in Physics and Biology. Glimpsing Reality* is an expanded version of that book.

The conversations — with Bohm, Pattee, Penrose, Rosen, Rosenfeld, Somorjai, Weizsacker, Wheeler, and Nobel prizewinners Heisenberg and Dirac, co-founders of quantum theory, and Prigogine — explore issues which have shaped modern physics and ones which hint at what may form the next scientific revolution. The discussions range over a set of basic problems in physical theory and their possible solutions — the understanding of space, time, and cosmology, the genesis of quantum theory and criticism of the standard interpretations of it, quantum and relativity theories and attempts to unite them — and the conceptual links between physics and biology. The approach is nontechnical, with an emphasis on the basic assumptions of modern science and their implications for understanding the world we live in.

All of the original interviews have been preserved. An introduction has been added to expand the thematic content of the mini-introductions preceding each interview. A new conversation (between the editors) has been added, a dialogue that places the fundamental ideas of quantum theory in a broad perspective to include work on chaos theory and superstring theory. Also new to this volume are two original essays that further develop the main thrust of the text — an exploration of the boundaries between physics and biology with the supervening idea being quantum theory and problems of its interpretation.

PAUL BUCKLEY was formerly associate professor of chemistry at l'Universite Laval. He has been science adviser to several government agencies and was, in 1992-3, Visiting Scientist in the Department of Physiology and Biophysics at Dalhousie University.

F. DAVID PEAT is a physicist and author of many books, including *Einstein's Moon: Bell's Theorem and the Curious Quest for Quantum Reality; Super-strings and the Search for the Theory of Everything;* and *Synchronicity, the Bridge between Matter and Mind.*

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Ideas in Physics and

the Link to Biology

EDITED BY PAUL BUCKLEY AND F. DAVID PEAT

UNIVERSITY OF TORONTO PRESS

Toronto Buffalo London

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© University of Toronto Press Incorporated 1996

Toronto Buffalo London

Printed in Canada

ISBN 0-8020-0575-6 (cloth)

ISBN 0-8020-6994-0 (paper)

Revised and expanded edition of *A Question of Physics:*

*Conversations in Physics and Biology*

(University of Toronto Press 1979).

Printed on acid-free paper

**Canadian Cataloguing in Publication Data**

Main entry under title:

Glimpsing reality : ideas in physics and the link

to biology

Rev. ed.

Previously published under title: A question of

physics.

ISBN 0-8020-0575-6 (bound) ISBN 0-8020-6994-0 (pbk.)

I. Physicists — Interviews. 2. Biologists—

Interviews. I. Buckley, Paul, 1938—

II. Peat, F. David, 1938— . III. Title: A

question of physics.

QC15.B83 1995 530 C95-932356-2

University of Toronto Press acknowledges

the financial assistance to its publishing program

of the Canada Council and the

Ontario Arts Council.

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TO OUR PARENTS

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Preface to the Revised Edition ix

Preface to the First Edition xi

Introduction to the Revised Edition xiii

CONVERSATIONS

Carl Friedrich von Weizsacker 61

Robert Rosen, Howard Hunt Pattee, and Raymond L. Somorjai:

a symposium in theoretical biology 111

F. David Peat and Paul Buckley: reflections after twenty years 151

ESSAYS

Paul Buckley: evolution and quantum consciousness 161

Robert Rosen: the Schrodinger question: What is life? fifty years later 168

Appendix: the troubles of quantum theory 191

Glossary 195

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Twenty years ago we asked several physicists, including two of the co-founders of quantum theory, Werner Heisenberg and Paul Dirac, to participate in the interviews which form the heart of this book. The present work is an expanded version of *A Question of Physics*, which appeared in 1979. All of the original interviews have been preserved without change. An introduction has been added to expand the thematic content of the mini-introductions preceding the conversations. A new conversation has been added, which is intended as a kind of update on developments since the first edition appeared, and two original essay-type contributions have been included to further develop some of the ideas presented in the main text.

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This book contains interviews with physicists, biologists, and chemists who have been involved in some of the most exciting discoveries in modern scientific thought. Some time ago we approached the Canadian Broadcasting Corporation with a proposal for a series of radio programs in which the revolutions taking place in physics during the last fifty years could be explored. The series would attempt to re-create the elation and argument, the disappointment and confusion, which physicists experienced during the origins of the quantum theory, along with some of the more exciting developments in quantum and relativity theories. By presenting science through the voices of its practitioners we hoped to convey a vivid, if at times unpolished, first-hand account. The resulting interviews are the origin of the present book, in which we have preserved the tempo and integrity of the original dialogues by indulging in the minimum amount of editing.

The success of the venture depended to a great extent upon the enthusiasm of the scientists we interviewed, and here we feel lucky in having selected physicists who have not only made important contributions to human thought but have also the ability to transmit their ideas clearly and directly.

In selecting topics for discussion we have betrayed our own prejudices. Rather than dwell upon the successes of modern physics we have explored the cracks in its fifty-year-old facade. We have concentrated on areas which, we feel, hint at the next scientific revolution. Perhaps in this context we own an apology to an important group of scientists — those engaged in elementary particle research. Some physicists feel that the search for ‘ultimate building-blocks of matter’ is one of the most promising modern areas of research. It was our belief, however, that there are {xii} deeper questions to be explored, and that the goal of ‘the most fundamental particle’ is somewhat of a throwback to the presuppositions of classical physics.

We have also included in this book, which is otherwise concerned with the problems of physics, a round-table discussion on theoretical biology. This young subject has all the intellectual challenge and excitement associated with physics in the twenties. Possibly in reading of the biologist's responses to his present difficulties we may be better able to understand the situation which faced physicists at a time when no atomic theory existed and there was simply an accumulation of spectroscopic data and a new and confusing quantum principle. The discussion also provides an example of the way in which traditional boundaries between the sciences are erased as similar questions are raised and mathematical techniques employed in diverse disciplines.

We hope that this book will serve as a useful overview for the practitioner of science and, at the same time, give the non-scientist some understanding of the revolution which has taken place in our understanding of the world. It was our intention to avoid technical terms and maintain a level of discussion accessible to a broad audience, but at times the scientists we interviewed became involved in questions which have troubled the scientific community for nearly half a century. They are to be excused for occasionally forgetting that ‘the collapse of the wave function,’ ‘non-classical logic,’ and ‘the Copenhagen interpretation’ are not topics which the average family discusses over morning coffee. We trust that our short appendix will be helpful in providing a background for such questions.

For assistance in the preparation of the manuscript, we extend our deepest thanks to Jane Wykes, who cheerfully undertook the arduous task of verifying the transcripts with the original tapes and typed the first edited version.

PAUL BUCKLEY

F. DAVID PEAT

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One of the things which makes physical theory intellectually attractive to many persons is the great amount of discussion which characterized quantum theory during its early stages and which continues enthusiastically, if less intensely, at the present time. Today there is fresh discussion centred on the foundations of quantum mechanics, and it appears that those foundations are not as firm as one had earlier thought. Though quantum mechanics is, in its formalism and in its detailed practice, extremely hard edged and very successful, it does invite alternative interpretations which are competing for attention. It seems to some that the revolution in science, which accompanied the early days of the century that is drawing to a close, is not yet finished despite the outstanding efforts of many great minds. But one really need not ask whether the revolution is finished for there are always the voices of dissent, and good questions keep getting asked even if decades go by before true attention is paid to them. All this just adds to the excitement which currently prevails in physics and which likely influences the work of other disciplines and activities. At the same time, however, one finds a note of seriousness, not to say unease, as a characteristic of the present mood.

Werner Heisenberg and Leon Rosenfeld are this book's spokespersons for the standard interpretation, also known as the Copenhagen interpretation, and they comment extensively upon its characteristics. Heisenberg calls the interpretation abstract, and possibly this has been a stumbling-block for some physicists, though the limitations of using ordinary language in physical descriptions are evident. Heisenberg and Rosenfeld communicate very clearly their sensitivities on the issue of language and the boundaries of classical concepts. They also give us many insights on the conditions of the origin of the quantum theory, thus leaving us with valuable pointers for contemporary studies in the history and philosophy of science. Of course, the interpretation may {xiv} be formulated more rigorously than can be set out in these two interviews, but most would admit that it is good to hear the story from those near the centre of the action in the discussions of the 1920s in Copenhagen, Göttingen, and other European cities.

There is one alternative interpretation which has been recently pointed to in the pages of *Scientific American* (May 1994) and this is David Bohm's ‘ontological interpretation.’ It is a serious contender among some theoretical physicists, biding its time until the day arrives and the orthodox interpretation no longer maintains its general acceptance. In his interview David Bohm explores meaning in a probing critique of attitudes in physics. Once again the question of the use of language is brought into the foreground where it belongs. The feeling that there is something newly positive about quantum theory is exemplified by Carl Weizsacker, who directs our attention to tense logic and to the issue of human time. He also discusses historical perspectives as they might apply to our period and this theory.

Paul Dirac surely represents the many physicists who remain untroubled by problems of interpretation; in his interview he resolutely refuses to talk about it. He prefers instead to comment upon certain cosmological issues, but he does make a few remarks on the then current state of theoretical physics. We are especially glad to have this interview as it is one of the very few that he consented to give. The interview with Roger Penrose introduces some of his imaginative work on twistors and the nature of space-time. John Wheeler ranges over geometrical ideas of space and time and also opens up some of the inner feelings possible in science, pointing toward its beauty. Wheeler also believes that the quantum theory allows us to feel that we are participating with Nature in the unfolding universe.

Ilya Prigogine firmly states a belief in participation based upon his results in the field of irreversible thermodynamics involving dissipative structures. This work seems to open out toward a biological frame and the more sophisticated notions of order which life sustains. Life itself is the subject of the mini-symposium involving Howard Pattee, Robert Rosen, Raymond Somorjai, and the co-authors. It becomes the locus of a spirited search for coherence in life's complexity and how best to grasp it. They attempt to demonstrate how physics and biology might relate in a more fruitful way than is found at present.

Along with its sharp edges and hard-won understanding, quantum mechanics may stimulate new feelings of participation in Nature. ‘Evolution and Quantum Consciousness’ by Paul Buckley is a series of reflections studying the implications of the coexistence of a theory of evolution and a quantum theory. In his essay, ‘The Schrödinger Question: What Is Life? Fifty Years Later,’ Robert Rosen examines some of the consequences for biology of asking this question today in Schrödinger's own manner. And because Erwin Schrödinger {xv} is one of the co-founders of the quantum theory this makes another connection for us between the sciences of matter and the sciences of life which are presented in this book.

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*Bateson, Gregory* An original thinker who has made contributions in various fields, including anthropology, psychiatry, and cybernetics. His writings have stressed the preoccupation of the mind with perceiving differences and differences of differences. This notion led Bateson to his Double Bind theory of schizophrenia, which was later applied by R.D. Laing in his studies of family influence in mental illness.

*combinatorics* A branch of mathematics concerned with the packing and arranging of patterns and designs and with combinations and permutations. Roger Penrose used combinatorics in the study of large networks of spinors in an attempt to derive the properties of space.

*commutation* In mathematics, the interchange of order of two quantities added, multiplied, etc. For the natural numbers the order of multiplication does not affect the result. The order is significant, however, when matrices (q.v.) are multiplied together. Matrices whose products depend on the order of multiplication are said to be non-commuting. The results of two quantum mechanical measurements generally depend on the order in which they are carried out; that is, they are non-commuting.

*complementarity* An idea propounded by Niels Bohr that nature is so rich that a single description will be insufficient to exhaust the definition of a phenomenon.

*confonnal invariance* A property attributed to an equation or theory which is unchanged by the operations of the conformal symmetry group. The conformal group is an extension of the Lorentz group (q.v.) and contains all symmetry operations in space-time which leave the light cone (q.v.) unchanged. The group relates to massless particles in special relativity. {196}

*continuum* Loosely speaking a continuum of numbers occurs when between any two numbers, no matter how close they are chosen, there can be found an infinity of other numbers. The natural numbers form a continuum, but the integers do not.

*dissipative structures* Statistical mechanics (q.v.) is often taught as that branch of science in which chance reigns supreme and structures are doomed to erosion through random fluctuations of their constituents. In contrast Ilya Prigogine points out that nature throws up stable complex structures which are capable of adaptation and survival. He sees such *dissipative structures* as arising in ‘open systems’ through the free exchange of energy and materials with the environment.

*Einstein-Rosen-Podolski paradox* Several of the founders of quantum mechanics had misgivings about the theory and the Copenhagen interpretation (see Appendix). To make their doubts more concrete Einstein, Schrödinger, Wigner, and others devised hypothetical situations (*gedanken* experiments) which lead to paradoxes when discussed. Bohr denied that such paradoxes existed and believed that such *gedanken* experiments, of which the Einstein-Rosen-Podolski experiment is one example, were capable of unambiguous interpretation.

*entropy* A quantity occurring in thermodynamics and statistical mechanics which relates to the ‘disorder’ present in a system. Unlike temperature, pressure, energy, and mass the entropy of a system cannot be measured directly but is inferred from other quantities.

*genotype, phenotype* The *genotype* is the total genetic information possessed by an organism. As the organism develops and interacts with its environment so a certain amount of its genetic potential (genotype) finds expression as size, shape, colour, behaviour, etc. This individual manifestation of the genotype by a particular organism or group of organisms is called the *phenotype.*

*Gödel's theorem* A consequence of the study of the foundations of mathematics and other deductive systems by the mathematician Kurt Gödel, the theorem states that certain deductive systems are inherently incomplete, in the sense that there always exist propositions within the system which cannot be proved. The implications which have followed from this theorem are often imaginative but controversial. It has been suggested, for example, that the theorem implies that the ability of computers will never duplicate that of the human brain.

*Hamilton-Jacobi theory* Classical mechanics is often presented as being based on Newton's laws of motion but the same results can be obtained using different assumptions and starting-points. One of these is the Hamilton-Jacobi theory, whose equations appear far more abstract than those of Newton's mechanics. Discussions of classical mechanics in the {197} Hamilton-Jacobi form illuminate correspondences with quantum mechanics.

*invariance* A property attributed to the equations of a particular theory (Maxwell's equations, Schrödinger's equation, field equations of general relativity, etc.) which are unchanged by a variety of symmetry transformations. The equations are then said to be invariant with respect to the operations of that particular symmetry group (q.v.).

*isospin* In the early days of quantum theory it was discovered that the electron possesses a two-valued degree of freedom, its spin (q.v.), in addition to its other degrees of freedom. It was later found that the idea of spin symmetry in space could be extended to include a degree of freedom corresponding to spin in an abstract space (isospace). By introducing the notion of isospin it became possible to consider two different particles as a single particle possessing different isospin states. The relationship between an abstract or ‘internal’ symmetry such as isospin and the symmetries of space-time is not clear.

*least action* One of the possible formulations of classical mechanics (see Hamilton-Jacobi theory). Whereas Newton's equations of motion build up the movement of particles by considering the instantaneous forces present at each element of their path, the principle of least action is based on an over-all property of the motion — that the particle assumes a trajectory that will minimize its ‘action.’

*light cone* The volume traced out in space-time from a source of light, which might be thought of as the ‘history,’ in space-time, of a light beam. Two space-time points which lie within each other's light cone are causally connected because they can exchange signals and experience each other's influences. Two points which lie outside each other's light cone cannot influence each other in any way since signals moving faster than the velocity of light would be required to connect them.

*Lorentz group* The group of symmetry operations in space-time which leave the laws of nature unchanged in the special theory of relativity.

*matrix* A mathematical object consisting of an array of numbers. Matrices obey different rules of operation than do ordinary numbers and, when multiplied, do not generally commute (q.v.). In Heisenberg's formulation of quantum mechanics the operations or experiments of quantum theory are represented by operations on matrices and the experimental results by the numbers found in these matrices.

*propositional calculus* The laws of logic could be thought of as a set of procedural rules together with initial assumptions. If each proposition is represented by a mathematical symbol and the rules of procedure by mathematical operations then a logical discourse can be represented by a set of symbolic manipulations. This symbolic form is called the {198} propositional calculus. The propositional calculus has been used to analyse the statements of quantum theory.

*Riemannian geometry* Bernard Riemann investigated geometries which are more general than those assumed in Euclid. The methods of Riemannian geometry were used by Einstein in the mathematical formulation of the general theory of relativity in which space-time possesses curvature and is non-Euclidean.

*Russell's paradox* Formulated during Bertrand Russell's investigations on the foundations of mathematics, the paradox concerns self-referential systems and can be stated as follows: if *R* is the set of all sets that do not belong to themselves, does *R* belong to itself? An informal statement of the paradox is made in terms of a barber in a certain village: This barber is the man who shaves all men who do not shave themselves. Who shaves the barber? Biological systems have sometimes been discussed in these terms; for example, dna contains all the genetic material that describes a system, and included in this description is a description of ona and all the information it contains.

*spinors, twistors* Spinors are mathematical objects that correspond to the electron's two-valued spin in quantum theory; spinors are also used in relativity theory. The twistor is a mathematical generalization of the two-component spinor made by Roger Penrose; it possesses four components and is of value in exploring the connections between quantum and relativity theories.

*statistical mechanics* Solids, liquids, and gases appear very different from the atoms and molecules which compose them. When attempts were first made to derive the properties of macroscopic systems from their constituents the astronomical number of entities involved made ‘exact’ calculations impossible. It was therefore decided to treat the motions of atomic particles in a statistical fashion using statistical mechanics and derive macroscopic properties such as pressure and temperature through averaging processes.

*superposition principle* A principle applied in quantum mechanics, where any linear superposition of allowable states of a system is itself an allowable state and, conversely, any state contains components from all other states.

*symmetry breaking* An idea which has become fashionable in modern physics, symmetry breaking occurs when a stable (or ground) state of a system appears to violate the symmetries which are present in the physical equations which govern it. For example, the equations which govern magnetic matter are spherically symmetric yet a ferromagnet violates this symmetry by exhibiting a preferred direction in space — the {199} direction of its magnetic axis. Attempts have been made in particle physics to relate symmetry breaking to the appearance of certain particles. One of us (DP) has attempted to relate symmetry breaking in large quantum systems to the manifestation of classical variables.

*symmetry group* A mathematical group containing the various symmetry operations (rotation through a certain angle, reflection about a certain axis, translation over a certain distance) which leave the appearance of an object or an equation unchanged.

*Wittgenstein's theory of language* Ludwig Wittgenstein, an Austrian philosopher who spent much of his creative life at Cambridge, was preoccupied with language and in the *Tractatus Logico-Philosophicus* attempted to fix the boundaries of unambiguous philosophical argument through a theory of language. Language was believed to ‘picture’ the world, and the domain of philosophy was the analysis of scientific propositions within this picture. In his later life Wittgenstein pointed out the limitations of his ‘picture’ theory of language and stressed the richness and variety of language and spoke of ‘language games.’ In *Philosophical Investigations* he concludes that many of the traditional problems of philosophy have arisen because language has been used in an insensitive fashion.