From Uncommon Wisdom: Conversations with remarkable people, by Fritjof Capra, pp. 17­21, 40­43, 48­63, 65­70.

Howling with the Wolves

Werner Heisenberg

My interest in the change of world view in science and society was stimulated when as a young physics student of nineteen I read Werner Heisenberg's Physics and Philosophy, his classic account of the history and philosophy of quantum physics. This book exerted an enormous influence on me and still does. It is a scholarly work, quite technical at times, but also full of personal and even highly emotional passages. Heisenberg, one of the founders of quantum theory and, along with Albert Einstein and Niels Bohr, one of the giants of modern physics, describes and analyzes in it the unique dilemma encountered by physicists during the first three decades of the century, when they explored the structure of atoms and the nature of subatomic phenomena. This exploration brought them in contact with a strange and unexpected reality that shattered the foundations of their world view and forced them to think in entirely new ways. The material world they observed no longer appeared as a machine, made up of a multitude of separate objects, but rather as an indivisible whole; a network of relationships that included the human observer in an essential way. In their struggle to grasp the nature of atomic phenomena, scientists became painfully aware that their basic concepts, their language, and their whole way of thinking were inadequate to describe this new reality.

In Physics and Philosophy, Heisenberg provides not only a brilliant analysis of the conceptual problems but also a vivid account of the tremendous personal difficulties these physicists faced when their research forced them to expand their consciousness. Their atomic experiments impelled them to think in new categories about the nature of reality, and it was Heisenberg's great achievement to recognize this clearly. The story of his struggle and triumph is also the story of the meeting and symbiosis of two exceptional personalities, Werner Heisenberg and Niels Bohr.

Heisenberg became involved in atomic physics at the age of twenty when he attended a series of lectures given by Bohr at Gottingen. The topic of the lectures was Bohr's new atomic theory, which had been hailed as an enormous achievement and was being studied by physicists throughout Europe. In the discussion following one of these lectures Heisenberg disagreed with Bohr on a particular technical point, and Bohr was so impressed by the clear arguments of this young student that he invited him to come for a walk so that they could carry on their discussion. This walk, which lasted for several hours, was the first meeting of two outstanding minds whose further interaction was to become the major force in the development of atomic physics.

Niels Bohr, sixteen years older than Heisenberg, was a man with supreme intuition and a deep appreciation for the mysteries of the world; a man influenced by the religious philosophy of Kierkegaard and the mystical writings of William James. He was never fond of axiomatic systems and declared repeatedly: "Everything I say must be understood not as an affirmation but as a question." Werner Heisenberg, on the other hand, had a clear, analytic, and mathematical mind and was rooted philosophically in Greek thought, with which he had been familiar since his early youth. Bohr and Heisenberg represented complementary poles of the human mind, whose dynamic and often dramatic interplay was a unique process in the history of modern science and led to one of its greatest triumphs.

When I read Heisenberg's book as a young student I was fascinated by his account of the paradoxes and apparent contradictions that plagued the investigation of atomic phenomena in the early 192Os. Many of these paradoxes were connected with the dual nature of subatomic matter, which appears sometimes as particles, sometimes as waves. "Electrons," physicists used to say in those days, "are particles on Mondays and Wednesdays and waves on Tuesdays and Thursdays." And the strange thing was that the more physicists tried to clarify the situation, the sharper the paradoxes became. It was only very gradually that physicists would develop a certain intuition for when an electron would appear as a particle and when as a wave. They would, as Heisenberg put it, "get into the spirit of the quantum theory" before developing its exact mathematical formulation. Heisenberg himself played a decisive role in this development. He saw that the paradoxes in atomic physics appeared whenever one tried to describe atomic phenomena in classical terms, and he was bold enough to throw away the classical conceptual framework. In 1925 he published a paper in which he abandoned the conventional description of electrons within an atom in terms of their positions and velocities, which was used by Bohr and everybody else, and replaced it with a much more abstract framework, in which physical quantities were represented by mathematical structures called matrices. Heisenberg's "matrix mechanics" was the first logically consistent formulation of quantum theory. It was supplemented one year later by a different formalism, worked out by Erwin Schrodinger and known as "wave mechanics." Both formalisms are logically consistent and are mathematically equivalent- the same atomic phenomenon can be described in two mathematically different languages.

At the end of 1926, physicists had a complete and logically consistent mathematical formalism, but they did not always know how to interpret it to describe a given experimental situation. During the following months Heisenberg, Bohr, Schrodinger, and others gradually clarified the situation in intensive, exhaustive, and often highly emotional discussions. In Physics And Philosophy Heisenberg described this crucial period in the history of quantum theory most vividly:

An intensive study of all questions concerning the interpretation of quantum theory in Copenhagen finally led to a complete . . . clarification of the situation. But it was not a solution which one could easily accept. I remember discussions with Bohr which went through many hours till very late at night and ended almost in despair; and when at the end of the discussion I went alone for a walk in the neighboring park I repeated to myself again and again the question: Can nature possibly be so absurd as it seemed to us in these atomic experiments?

Heisenberg recognized that the formalism of quantum theory cannot be interpreted in terms of our intuitive notions of space and time or of cause and effect; at the same time he realized that all our concepts are linked to these intuitive notions. He concluded that there was no other way out than to retain the classical intuitive concepts but to restrict their applicability. Heisenberg's great achievement was to express these limitations of classical concepts in a precise mathematical form which now bears his name and is known as the Heisenberg uncertainty principle. It consists of a set of mathematical relations that determine the extent to which classical concepts can be applied to atomic phenomena and thus stake out the limits of human imagination in the subatomic world.

The uncertainty principle measures the extent to which the scientist influences the properties of the observed objects through the process of measurement. In atomic physics scientists can no longer play the role of detached, objective observers; they are involved in the world they observe, and Heisenberg's principle measures this involvement. At the most fundamental level the uncertainty principle is a measure of the unity and interrelatedness of the universe. In the 192Os physicists, led by Heisenberg and Bohr, came to realize that the world is not a collection of separate objects but rather appears as a web of relations between the various parts of a unified whole. our classical notions, derived from our ordinary experience, are not fully adequate to describe this world. Werner Heisenberg, like no one else, has explored the limits of human imagination, the limits to which our conventional concepts can be stretched, and the extent to which we must become involved in the world we observe. His greatness was that he not only recognized these limitations and their profound philosophical implications but was able to specify them with mathematical clarity and precision.

At the age of nineteen, I did not by any means understand all of Heisenberg's book. In fact, most of it remained a mystery to me at this first reading, but it sparked a fascination with that epochal period of science that has never left me since. For the time being, however, a more thorough study of the paradoxes of quantum physics and their resolution had to wait while, for several years, I received a thorough education in physics; first in classical physics, and then in quantum mechanics, relativity theory, and quantum field theory. Heisenberg's Physics and Philosophy remained my companion during these studies and, looking back on this time, I now can see that it was Heisenberg who planted the seed that would mature, more than a decade later, in my systematic investigation of the limitations of the Cartesian world view. "The Cartesian partition," wrote Heisenberg, "has penetrated deeply into the human mind during the three centuries following Descartes, and it will take a long time for it to be replaced by a really different attitude toward the problem of reality." . . .

On April 11, 1972, I drove to Munich to meet the man who had had a decisive influence on my scientific career and my philosophical interests, the man who was considered one of the intellectual giants of our century. Heisenberg received me in his office at the Max Planck Institute, and when I sat down face to face with him at his desk I was immediately impressed. He was impeccably dressed in a suit and tie, his tie pinned to his shirt by a pin that formed the letter h, which is the symbol for Planck's constant, the fundamental constant of quantum physics. I noticed these details gradually during our conversation. What impressed me most right away was Heisenberg's clear blue­gray eyes, holding forth a gaze that showed clarity of mind, total presence, compassion, and serene detachment. For the first time I felt that I was sitting with one of the great sages of my own culture.

I began the conversation by asking Heisenberg to what extent he was still involved in physics, and he told me that he was pursuing a research program with a group of colleagues, that he came to the Institute every day, and that he was following the research in fundamental physics around the world with great interest. When I asked him what kind of results he still hoped to achieve, he gave me a brief outline of the goals of his research program, but he also said that he found as much pleasure in the process of research as in achieving those goals. I had the strong feeling that this man had pursued his discipline to the point of complete self­realization.

What was most astonishing about these first few minutes of our conversation was that I felt completely at ease. There was absolutely no trace of any posturing or pomp; Heisenberg never made me feel the difference in our status even for a second. We began to discuss recent developments in particle physics, and to my amazement I found myself contradicting Heisenberg only a few minutes into our discussion. My initial feelings of awe and reverence had quickly given way to the intellectual excitement felt in a good discussion. There was complete equality-two physicists discussing the ideas they found most exciting in the science they loved.

Naturally, our conversation soon drifted to the 192Os, and Heisenberg entertained me with many fascinating stories of that period. I realized that he loved to talk about physics and to reminisce about those exciting years. For example, he gave me a vivid description of discussions between Erwin Schrodinger and Niels Bohr that took place when Schrodinger visited Copenhagen in 1926 and presented his newly discovered wave mechanics, including the celebrated equation that bears his name, at Bohr's institute. Schrodinger's wave mechanics was a continuous formalism involving familiar mathematical techniques, while Bohr's interpretation of quantum theory was based on Heisenberg's discontinuous and highly unorthodox matrix mechanics, which involved so­called quantum jumps.

Heisenberg told me that Bohr tried to convince Schrodinger of the merits of the discontinuous interpretation in long debates that often took entire days. In one of these debates Schrodinger exclaimed in great frustration: "If one has to stick to this damned quantum jumping, then I regret having ever been involved in this thing." Bohr, however, pressed on and berated Schrodinger so intensely that Schrodinger finally got sick. "I remember well," Heisenberg continued with a smile, "how poor Schrodinger was lying in bed in Bohr's home and Mrs. Bohr was serving him a bowl of soup, while Niels Bohr was sitting on his bed insisting: 'But Schrodinger, you must admit . . .' "

When we talked about the developments that led Heisenberg to formulate the uncertainty principle, he told me an interesting detail that I had not found in any written account of the period. He said that in the early 192Os Niels Bohr suggested to him during one of their long philosophical conversations that they might have reached the limits of human understanding in the realm of the very small. Maybe, Bohr wondered, physicists would never be able to Bmd a precise formalism to describe atomic phenomena. Heisenberg added with a fleeting smile, his gaze lost in reverie, that it was his great personal triumph to prove Bohr wrong on this account.

While Heisenberg was telling me these stories, I noticed that he had Jacques Monod's Chance and Necessity lying on his desk, and since I had just read this book myself with great interest I was very curious to hear Heisenberg's opinion. I told him that I thought Monod, in his attempt to reduce life to a game of roulette, governed by quantum­mechanical probabilities, had not really understood quantum mechanics. Heisenberg agreed with me and added that he found it sad that Monod's excellent popularization of molecular biology was accompanied by such bad philosophy.

This led me to discuss the broader philosophical framework underlying quantum physics and in particular its relation to that of Eastern mystical traditions. Heisenberg told me that he had repeatedly thought that the great contributions of Japanese physicists during recent decades might be owing to a basic similarity between the philosophical traditions of the East and the philosophy of quantum physics. I remarked that the discussions I had had with Japanese colleagues had not shown me that they were aware of this connection, and Heisenberg agreed: "Japanese physicists have a real taboo against speaking about their own culture, so much have they been influenced by the United States." Heisenberg believed that Indian physicists were somewhat more open in this respect, which had also been my experience.

When I asked Heisenberg about his own thoughts on Eastern philosophy, he told me to my great surprise not only that he had been well aware of the parallels between quantum physics and Eastern thought, but also that his own scientific work had been influenced, at least at the subconscious level, by Indian philosophy.

In 1929 Heisenberg spent some time in India as the guest of the celebrated Indian poet Rabindranath Tagore, with whom he had long conversations about science and Indian philosophy. This introduction to Indian thought brought Heisenberg great comfort, he told me. He began to see that the recognition of relativity, interconnectedness, and impermanence as fundamental aspects of physical reality, which had been so difficult for himself and his fellow physicists, was the very basis of the Indian spiritual traditions. "After these conversations with Tagore," he said, "some of the ideas that had seemed so crazy suddenly made much more sense. That was a great help for me."

At this point I could not help but pour out my heart to Heisenberg. I told him that I had come across the parallels between physics and mysticism several years ago, had begun to study them systematically, and was convinced that this was an important line of research. However, I could not find any financial support from the scientific community and found working without such support extremely difficult and draining. Heisenberg smiled: "I, too, am always accused of getting too much into philosophy." When I pointed out that our situations were rather different, he continued his warm smile and said: "You know, you and I are physicists of a different kind. But every now and then we just have to howl with the wolves." [a German equivalent of to run with the pack] These extremely kind words of Werner Heisenberg-"You and I are physicists of a different kind"-helped me, perhaps more than anything else, to keep my faith during the difficult times.

At my second visit, Heisenberg received me as if we had known each other for years, and again we spent over two hours in animated conversation. our discussion of current developments in physics this time was concerned mostly with the "bootstrap" approach to particle physics in which I had become interested in the meantime and about which I was very curious to hear Heisenberg's opinion.

The other purpose of my visit, of course, was to find out what Heisenberg thought about The Tao of Physics. I showed the manuscript to him chapter by chapter, briefly summarizing the content of each chapter and emphasizing especially the topics related to his own work. Heisenberg was most interested in the entire manuscript and very open to hearing my ideas. I told him that I saw two basic themes running through all the theories of modern physics, which were also the two basic themes of all mystical traditions-the fundamental interrelatedness and interdependence of all phenomena and the intrinsically dynamic nature of reality. Heisenberg agreed with me as far as physics was concerned and he also told me that he was well aware of the emphasis on interconnectedness in Eastern thought. However, he had been unaware of the dynamic aspect of the Eastern world view and was intrigued when I showed him with numerous examples from my manuscript that the principal Sanskrit terms used in Hindu and Buddhist philosophy-brahman, rta, lila, karma, samsara, etc.-had dynamic connotations. At the end of my rather long presentation of the manuscript Heisenberg said simply: "Basically, I am in complete agreement with you."

As after our first meeting, I left Heisenberg's office in extremely high spirits. Now that this great sage of modern science had shown so much interest in my work and was so much in agreement with my results I was not afraid to take on the rest of the world. I sent Heisenberg one of the first copies of The Tao of Physics when it came out in November 1975, and he wrote to me right away that he was reading it and would write to me again once he had read more. This letter was to be our last communication. Werner Heisenberg died a few weeks later, on my birthday, while I was sitting on the sunny deck of my apartment in Berkeley consulting the I Ching. I shall always be grateful to him for writing the book that was the starting point of my search for the new paradigm and has given me continuing fascination with this subject, and for his personal support and inspiration. . . .

Geoffery Chew

The famous words of Isaac Newton, "I am standing on the shoulders of giants," are valid for every scientist. We all owe our knowledge and our inspiration to a "lineage" of creative geniuses. My own work within and beyond the field of science has been influenced by a large number of great scientists, several of whom play major roles in this story. As far as physics is concerned, my major sources of inspiration have been two outstanding men: Werner Heisenberg and Geoffrey Chew. Chew, who is now sixty, belongs to a different generation of physicists than Heisenberg, and although very well known within the physics community he is by no means as famous as the great quantum physicists. However, I have no doubt that future historians of science will judge his contributions to physics as equal to theirs. While Einstein revolutionized scientific thought with his theory of relativity, and Bohr and Heisenberg, with their interpretation of quantum mechanics, introduced changes so radical that even Einstein refused to accept them, Chew has made the third revolutionary step in twentieth­century physics. His "bootstrap" theory of particles unifies quantum mechanics and relativity theory into a theory that displays both the quantum and relativistic aspects of subatomic matter to their fullest extents and, at the same time, represents a radical break with the entire Western approach to fundamental science.

According to the bootstrap hypothesis, nature cannot be reduced to fundamental entities, like fundamental building blocks of matter, but has to be understood entirely through selfconsistency. Things exist by virtue of their mutually consistent relationships, and all of physics has to follow uniquely from the requirement that its components be consistent with one another and with themselves. The mathematical framework of bootstrap physics is known as S­matrix theory. It is based on the concept of the S matrix, or "scattering matrix," which was originally proposed by Heisenberg in the 194Os and has been developed, over the past two decades, into a complex mathematical structure, ideally suited to combine the principles of quantum mechanics and relativity theory. Many physicists have contributed to this development, but Geoffrey Chew has been the unifying force and philosophical leader in S­matrix theory, much in the same way that Niels Bohr was the unifying force and philosophical leader in the development of quantum theory half a century earlier.

Over the past twenty years, Chew, together with his collaborators, has been using the bootstrap approach to develop a comprehensive theory of subatomic particles, along with a more general philosophy of nature. This bootstrap philosophy not only abandons the idea of fundamental building blocks of matter, but accepts no fundamental entities whatsoever-no fundamental constants, laws, or equations. The material universe is seen as a dynamic web of interrelated events. None of the properties of any part of this web is fundamental; they all follow from the properties of the other parts, and the overall consistency of their interrelations determines the structure of the entire web.

The fact that the bootstrap philosophy does not accept any fundamental entities makes it, in my opinion, one of the most profound systems of Western thought. At the same time, it is so foreign to our traditional scientific ways of thinking that it is pursued by only a small minority of physicists. Most physicists prefer to follow the traditional approach, which has always been bent on finding the fundamental constituents of matter. Accordingly, basic research in physics has been characterized by an ever­progressing penetration into the world of submicroscopic dimensions, down into the realms of atoms, nuclei, and subatomic particles. In this progression, the atoms, nuclei, and hadrons (i.e., the protons, neutrons, and other strongly interacting particles) were, in turn, considered to be "elementary particles." None of them, however, fulfilled that expectation. Each time, these particles turned out to be composite structures themselves, and each time physicists hoped that the next generation of constituents would finally reveal themselves as the ultimate components of matter. The most recent candidates for the basic material building blocks are the so­called quarks, hypothetical constituents of hadrons, which have not been observed so far and whose existence is made extremely doubtful by serious theoretical objections. In spite of these difficulties, most physicists still hang on to the idea of basic building blocks of matter, which is so deeply ingrained in our scientific tradition.

Bootstrap and Buddhism

When I first became aware of Chew's approach to understanding nature not as an assemblage of basic entities with certain fundamental properties, but rather as a dynamic web of interrelated events, in which no part is more fundamental than any other part, I was immediately attracted to it. At that time, I was in the midst of my study of Eastern philosophies, and I realized right away that the basic tenets of Chew's scientific philosophy stood in radical contrast to the Western scientific tradition but were in full agreement with Eastern, and especially Buddhist, thought. I immediately set out to explore the parallels between Chew's philosophy and that of Buddhism, and I summarized my results in a paper entitled "Bootstrap and Buddhism." I argued in this paper that the contrast between "fundamentalists" and "boots/rappers" in particle physics reflects the contrast between two prevailing currents in Western and Eastern thought. The reduction of nature to fundamentals, I pointed out, is basically a Greek attitude, which arose in Greek philosophy together with the dualism between spirit and matter, whereas the view of the universe as a web of relationships is characteristic of Eastern thought. I showed how the unity and mutual interrelation of all things and events have found their clearest expression and most far­reaching elaboration in Mahayana Buddhism, and how this school of Buddhist thought is in complete harmony with bootstrap physics both in its general philosophy and in its specific picture of matter.

Before writing this paper I had heard Chew speak at several physics conferences and had met him briefly when he came to give a seminar at UC Santa Cruz, but I did not really know him. In Santa Cruz I was very impressed by his highly philosophical and thoughtful talk, but also rather intimidated. I would have loved to have a serious discussion with him, but I felt that I was far too ignorant for it and merely asked Chew a rather trivial question after the seminar. Two years later, however, after writing my paper, I was confident that my thinking had now evolved to a point where I could have a real exchange of ideas with Chew, and I sent him a copy of the paper and asked him for his comments. Chew's answer was very kind and extremely exciting to me. "Your way of describing the [bootstrap] idea," he wrote, "should make it more palatable to many and to some, perhaps, so esthetically appealing as to be irresistible."

This letter was the beginning of an association which has been a source of continuing inspiration to me and has decisively shaped my entire outlook on science. Later on Chew told me, to my great surprise, that the parallels between his bootstrap philosophy and Mahayana Buddhism had not been new to him when he received my article. In 1969, he told me, he and his family were preparing to spend a month in India, and during this preparation his son, half­humorously, pointed out the parallels between the bootstrap approach and Buddhist thought. "I was stupefied,'' said Chew. "I just couldn't believe it, but then my son went on and explained it to me, and it made a lot of sense." I wondered whether Chew, like so many physicists, felt threatened by having his ideas compared to those in mystical traditions. "No," he told me, "because I had already been accused of being on the mystical side. People had often commented that my approach to physics was not grounded in the same way that most physicists approached things. So it wasn't such a shock to me. It was a shock, but I quickly realized the appropriateness of the comparison."

Many years later, Chew described his encounter with Buddhist philosophy in a public lecture he gave in Boston, which was, to me, a beautiful demonstration of the depth and maturity of his thought:

I remember very keenly my astonishment and chagrin-I think it was in 1969-when my son, who was then a senior in high school and had been studying Oriental philosophy, told me about Mahayana Buddhism. I was stunned, and there was a sense of embarrassment in discovering that my research had, somehow, become based on ideas that sounded terribly unscientific when they are associated with Buddhist teachings.

Now, of course, other particle physicists, since they are working with quantum theory and relativity, are in the same position. However, most of them are reluctant to admit, even to themselves, what is happening to their discipline, which is, of course, beloved for its dedication to objectivity. But for me, the embarrassment that I felt in 1969 has gradually been replaced by a sense of awe, which is combined with a sense of gratitude that I am alive to see such a period of development.

During my visit to California in 1973, Chew invited me to give a lecture about the parallels between modern physics and Eastern mysticism at UC Berkeley, where he received me very graciously and spent most of the day with me. Since I had not made any significant contributions to theoretical particle physics for the previous couple of years and was well aware of the workings of the academic system, I knew very well that it was absolutely impossible for me to obtain a research position at the Lawrence Berkeley Laboratory, one of the most prestigious physics institutes in the world, where Chew headed the theory group. Nevertheless, I asked Chew at the end of the day whether he saw any possibility for me to come here and work with him. He told me, as I had expected, that he would not be able to get a research grant for me, but he added immediately that he would be delighted to have me here and to extend his hospitality and full access to the Lab's facilities whenever I chose to come. I was, of course, very excited and encouraged by this offer, which I accepted happily two years later.

When I wrote The Tao of Physics, I made the close correspondence between bootstrap physics and Buddhist philosophy its high point and finale. So, when I discussed the manuscript with Heisenberg, I was naturally very curious to hear his opinion about Chew's approach. I expected Heisenberg to be in sympathy with Chew, because in his writings he often emphasized the conception of nature as an interconnected network of events, which is also the starting point of Chew's theory. Moreover, it was Heisenberg who originally proposed the concept of the S matrix, which Chew and others developed into a powerful mathematical formalism twenty years later.

Indeed, Heisenberg told me that he was in complete agreement with the bootstrap picture of particles being dynamic patterns in an interconnected network of events. He did not believe in the quark model and even went so far as to call it nonsense. However, Heisenberg, like most physicists today, could not accept Chew's view that there should be nothing fundamental in one's theory, and in particular no fundamental equations. In 1958 Heisenberg had proposed just such an equation, which soon became known popularly as "Heisenberg's world formula," and he spent the rest of his life trying to derive the properties of all subatomic particles from this equation. So he was naturally very attached to the idea of a fundamental equation and unwilling to accept the bootstrap philosophy to its full? radical extent. "There is a fundamental equation," he told me, "whatever its formulation may be, from which the spectrum of elementary particles can be derived. one must not escape into the fog. Here I disagree with Chew."

Heisenberg did not succeed in deriving the spectrum of elementary particles from his equation, but Chew has recently succeeded in doing just that with his bootstrap theory. In particular, he and his collaborators have been able to derive results characteristic of quark models without any need to postulate the existence of physical quarks; to do, so to speak, quark physics without quarks.

Before that breakthrough, the bootstrap program had become severely mired in the mathematical complexities of S­matrix theory. In the bootstrap view, every particle is related to every other particle, including itself, which makes the mathematical formalism highly nonlinear, and this nonlinearity was impenetrable until recently. In the mid­sixties, therefore, the bootstrap approach went through a crisis of faith, and the support for Chew's idea dwindled to a handful of physicists. At the same time, the quark idea gained momentum, and its adherents presented the bootstrappers with the challenge to explain the results achieved with the help of quark models.

The breakthrough in bootstrap physics was initiated in 1974 by a young Italian physicist, Gabriele Veneziano, but when I saw Heisenberg in January 1975 I was not aware of Veneziano's discovery. If I had been, I might have been able to show Heisenberg how the first outlines of a precise bootstrap theory were already emerging, out of the fog as it were.

The essence of Veneziano's discovery was the recognition that topology-a formalism well known to mathematicians but never before applied to particle physics-can be used to define categories of order in the interconnectedness of subatomic processes. With the help of topology, one can establish which interconnections are the most important and formulate a first approximation in which only those are taken into account, and then one can add the others in successive approximative steps. In other words, the mathematical complexity of the bootstrap scheme can be disentangled by incorporating topology into the S­matrix framework. When this is done, only a few special categories of ordered relationships turn out to be compatible with the well­known properties of the S matrix. These categories of order are precisely the quark patterns observed in nature. Thus, the quark structure appears as a manifestation of order and necessary consequence of self­consistency, without any need to postulate quarks as physical constituents of hadrons.

When I arrived in Berkeley in April 1975, Veneziano was visiting LBL (the Lawrence Berkeley Laboratory) and Chew and his collaborators were extremely excited about the new topological approach. For me, too, this was a very fortunate turn of events, as it gave me the opportunity to reenter active research in physics with relative ease after a lapse of three years. Nobody in Chew's research group knew anything about topology, and when I joined the group I had no research project on my hands; so I threw myself wholeheartedly into the study of topology and soon acquired some expertise in it, which made me a valuable member of the group. By the time everybody else caught up I had also reactivated my other skills and was able to participate fully in the topological bootstrap program.

Discussions with Chew

I have remained a member of Chew's research team at LBL ever since 1975 with greatly varying degrees of involvement, and this association has been extremely satisfying and enriching for me. Not only have I been very happy to be back in physics, I have had the unique privilege of a close collaboration and continual exchange of ideas with one of the truly great scientists of our time. My many interests beyond physics have kept me from doing research with Chew full time, and the University of California has never found it appropriate to support my part­time research, or to acknowledge my books and other publications as valuable contributions to the development and communication of scientific ideas. But I do not mind. Shortly after I returned to California, The Tao of Physics was published in the United States by Shambhala and then by Bantam Books, and has since become an international best­seller. The royalties from these editions and the fees for lectures and seminars, which I have given with increasing frequency, finally put an end to my financial difficulties, which had persisted through most of the seventies.

Over the past ten years I have seen Geoffrey Chew regularly and have spent hundreds of hours in discussion with him. The subject of our discussions was usually particle physics and, more specifically, the bootstrap theory, but we were in no way restricted by it and would often branch out quite naturally to discuss the nature of consciousness, the origin of space­time, or the nature of life. Whenever I was actively engaged in research, I would participate in all seminars and meetings of our research group, and when I was busy lecturing or writing I would see Chew at least every two or three weeks for a couple of hours of intensive discussions.

These sessions have been very useful for both of us. They have helped me enormously in keeping current with Chew's research and, more generally, with the important developments in particle physics. on the other hand, they have forced Chew to summarize the progress of his work at regular intervals, using the appropriate technical language to its full extent but concentrating on the principal developments without getting lost in unnecessary details or minor temporary difficulties. He has often told me that these discussions were a valuable aid for him in keeping his mind attentive to the grand design of the research program. Since I would enter the discussions with full knowledge of the main achievements and outstanding problems but unencumbered by the details of the day­to­day research routine, I was often able to pinpoint inconsistencies or ask for clarification in a way that would stimulate Chew and lead him to new insights. over the years I got to know Geoff, as Chew is commonly called by his friends and colleagues, so well, and my thinking was so much influenced by his, that our interchanges would often generate a state of excitement and mental resonance that is very conducive to creative work. For me, these discussions will always belong among the high points of my scientific life.

Anybody who meets Geoff Chew will immediately find him a very kind and gentle person, and anybody who engages him in a serious discussion is bound to be impressed by the depth of his thinking. He has the habit of addressing every question or problem at the deepest possible level. Again and again I have heard him deal with questions for which I had ready­made answers as soon as I heard them, by saying slowly, after a few moments of reflection, "Well, you are asking a very important question," and then carefully mapping out the broad context of the question and advancing a tentative answer at its deepest and most significant level.

Chew is a slow, careful, highly intuitive thinker, and to watch him struggle with a problem has become a fascinating experience for me. I would often see an idea rising from the depth of his mind to the conscious level, and would watch him depict it in tentative gestures with his large, expressive hands before he would carefully and slowly formulate it in words. I have always felt that Chew has his S matrix in his bones; that he uses his body language to give these highly abstract ideas a tangible shape.

From the beginning of our discussions I had wondered about Chew's philosophical background. I knew that Bohr's thinking was influenced by Kierkegaard and William James, that Heisenberg had studied Plato, that Schrodinger had read the Upanishads. I had always known Chew as a very philosophical person and, given the radical nature of his bootstrap philosophy, I was extremely curious about any influences of philosophy, art, or religion on his thinking. But whenever I talked to Chew I became so absorbed in our discussions of physics that it seemed a waste of time to break the flow of the discussion and ask Chew about his philosophical background. It took me many years to put that question to Chew, and when I finally did I was utterly surprised by his answer.

He told me that in his younger years he had tried to model himself after his teacher, Enrico Fermi, who was famous for his pragmatic approach to physics. "Fermi was an extreme pragmatist who was not really interested in philosophy at all," Chew explained. "He simply wanted to know the rules that would allow him to predict the results of experiments. I remember him talking about quantum mechanics and laughing scornfully at people who spent their time worrying about the interpretation of the theory, because he knew how to use those equations to make predictions. And for a long time I tried to think that I was going to behave as much as possible in the spirit of Fermi."

It was only much later, Chew told me, when he started to write and give talks, that he began to think about philosophical questions. When I asked him to tell me about people who had influenced his thinking, all the names he mentioned were those of physicists, and when I wondered in great surprise whether he had been influenced by any school of philosophy, or anything outside physics, he simply replied, "Well, I am certainly not aware of any. I can't identify anything like that."

It seems, then, that Chew is a truly original thinker who derived his revolutionary approach to physics and his profound philosophy of nature from his own experience of the world of subatomic phenomena; an experience which, of course, can only be indirect, through complicated and delicate instruments of observation and measurement, but which, for Chew, nevertheless is very real and meaningful. one of Chew's secrets may be that he immerses himself completely in his work and is capable of intense concentration for prolonged periods of time. In fact, he told me that his concentration is virtually continuous: "one aspect of the way I operate is that I almost never stop thinking about the problem of the moment. I rarely turn off, unless something is very immediate, like driving a car when it's dangerous. Then I will stop thinking, but for me continuity is crucial; I have to keep going."

Chew also told me that he very rarely reads anything outside his domain of research, and he said that he remembered an anecdote about Paul Dirac, one of the famous quantum physicists, who once replied to the question whether he had read a certain book with absolute and straightforward seriousness: "I never read. It prevents me from thinking." "Now, I will read things," Chew said laughingly as he recounted the anecdote, "but I have to have a very specific motivation for doing so."

One might think that Chew's continuous and intense concentration on his conceptual world would make him a rather cold and somewhat obsessed person, but just the opposite is true. He has a warm and open personality; he hardly ever appears to be tense or frustrated and will often laugh happily and spontaneously during a discussion. As long as I have known Geoff Chew, I have experienced him as being very much at peace with himself and the world. He is extremely kind and considerate and manifests in his everyday life the tolerance that he considers to be characteristic of his bootstrap philosophy. "A physicist who is able to view any number of different, partially successful models without favoritism," he wrote in one of his papers, "is automatically a bootstrapper." I have always been impressed by the harmony between Chew's science, his philosophy, and his personality, and although he considers himself a Christian and is close to the Catholic tradition, I cannot help feeling that his approach to life shows, basically, a Buddhist attitude.

Bootstrapping space­time

Since bootstrap physics is not based on any fundamental entities, the process of theoretical research differs in many ways from that of orthodox physics. In contrast to most physicists, Chew does not dream of a single decisive discovery that will establish his theory once and for all, but rather sees his challenge in constructing, slowly and patiently, an interconnected network of concepts, none of which is any more fundamental than the others. As the theory progresses, the interconnections in this network become more and more precise; the entire network comes more and more into focus, as it were.

In this process, the theory also becomes ever more exciting as more and more concepts are "bootstrapped"-that is, explained through the overall self­consistency of the conceptual web. According to Chew, this bootstrapping will include the basic principles of quantum theory, our conception of macroscopic space­time, and, eventually, even our conception of human consciousness. "Carried to its logical extreme," writes Chew, "the bootstrap conjecture implies that the existence of consciousness, along with all other aspects of nature, is necessary for self­consistency of the whole."

At present, the most exciting part of Chew's theory is the prospect of bootstrapping space­time, which appears to be feasible in the near future. In the bootstrap theory of particles, there is no continuous space­time. Physical reality is described in terms of isolated events that are causally connected but are not embedded in continuous space and time. Space­time is introduced macroscopically, in connection with the experimental apparatus, but there is no implication of a microscopic spacetime continuum.

The absence of continuous space and time is, perhaps, the most radical and most difficult aspect of Chew's theory, for physicists as well as for lay people. Chew and I recently discussed the question of how our everyday experience of separate objects moving through continuous space and time can be explained by such a theory. Our conversation was triggered by a discussion of the well­known paradoxes of quantum theory.

"I think that this is one of the most puzzling aspects of physics," Chew began, "and I can only state my own point of view, which I don't think is shared by anybody else. My feeling is that the principles of quantum mechanics, as they are stated, are not satisfactory and that the pursuit of the bootstrap program is going to lead to a different statement. I think that the form of this statement will include such things as: you should not try to express the principles of quantum mechanics in an a priori accepted space­time. That is the flaw of the present situation. Quantum mechanics has something intrinsically discrete about it, whereas the idea of space­time is continuous. I believe that if you try to state the principles of quantum mechanics after having accepted space­time as an absolute truth, then you will get into difficulties. My feeling is that the bootstrap approach is going to eventually give us simultaneous explanations for space­time, quantum mechanics, and the meaning of Cartesian reality. All these will come together, somehow, but you will not be able to begin with space­time as a clear, unambiguous basis and then put these other ideas on top of it."

"Nevertheless," I argued, "it seems evident that atomic phenomena are embedded in space­time. You and I are embedded in space and time, and so are the atoms we consist of. Space­time is a concept that is extremely useful, so what do you mean by the statement that one should not embed atomic phenomena in space­time?"

"Well, first of all, I take it as obvious that the quantum principles render inevitable the idea that objective Cartesian reality is an approximation. You cannot have the principles of quantum mechanics and, at the same time, say that our ordinary ideas of external reality are an exact description. You can produce enough examples, showing how a system subject to quantum principles begins to exhibit classical behavior when it becomes sufficiently complex. That is something which people have repeatedly done. You can actually show how classical behavior emerges as an approximation to quantum behavior. So the classical Cartesian notion of objects and all of Newtonian physics are approximations. I don't see how they can be exact. They have to depend on the complexity of the phenomena which are being described. A high degree of complexity, of course, can end up averaging out in such a way that it produces effective simplicity. This effect makes classical physics possible."

"So you have a quantum level at which there are no solid objects and at which classical concepts do not hold; and then, as you go to higher and higher complexity, the classical concepts somehow emerge?"


"And you are saying, then, that space­time is such a classical concept?"

"That's right. It emerges along with the classical domain and you should not accept it at the beginning."

"And now you have also some ideas about­ how space­time will emerge at high complexity?"

"Right. The key notion is the idea of gentle events, and the whole idea is uniquely associated with photons."

Chew then went on to explain that photons-the particles of electromagnetism and light-have unique properties, including that of being massless, which allow them to interact with other particles in events that cause only very slight disturbances. There can be an infinite number of these "gentle events," and as they build up, they result in an approximate localization of the other particle interactions, and thus the classical notion of isolated objects emerges.

"But what about space and time?" I asked.

"Well, you see, the understanding of what a classical object is, of what an observer is, of what electromagnetism is, of what space­time is-all these are tied together. once you have the idea of gentle photons in the picture, you can begin to recognize certain patterns of events as representing an observer looking at something. In this sense, I would say, you can hope to make a theory of objective reality. But the meaning of spacetime will come at the same moment. You will not start with space­time and then try to develop a theory of objective reality . . . .

Geoffrey Chew has had an enormous influence on my world view, my conception of science, and my way of doing research. Although I have repeatedly branched out very far from my original field of research, my mind is essentially a scientific mind, and my approach to the great variety of problems I have come to investigate has remained a scientific one, albeit within a very broad definition of science. It was Chew's influence, more than anything else, that helped me to develop such a scientific attitude in the most general sense of the term.

My continuing association and intensive discussions with Chew, together with my studies and practice of Buddhist and Taoist philosophy, have allowed me to become completely comfortable with one of the most radical aspects of the new scientific paradigm-the lack of any firm foundation. Throughout the history of Western science and philosophy, there has always been the belief that any body of knowledge had to be based on firm foundations. Accordingly, scientists and philosophers throughout the ages have used architectural metaphors to describe knowledge. Physicists looked for the "basic building blocks" of matter and expressed their theories in terms of "basic" principles, "fundamental" equations, and "fundamental" constants. Whenever major scientific revolutions occurred it was felt that the foundations of science were moving. Thus Descartes wrote in his celebrated Discourse on Method:

In so far as [the sciences] borrow their principles from philosophy, I considered that nothing solid could be built on such shifting foundations.

Three hundred years later, Heisenberg wrote in his Physics and Philosophy that the foundations of classical physics, that is, of the very edifice Descartes had built, were shifting:

The violent reaction to the recent development of modern physics can only be understood when one realizes that here the foundations of physics have started moving; and that this motion has caused the feeling that the ground would be cut from under science.

Einstein, in his autobiography, described his feelings in terms very similar to Heisenberg's:

It was as if the ground had been pulled out from under one, with no firm foundation to be seen anywhere, upon which one could have built.

It appears that the science of the future will no longer need any firm foundations, that the metaphor of the building will be replaced by that of the web, or network, in which no part is more fundamental than any other part. Chew's bootstrap theory is the first scientific theory in which such a "web philosophy" has been formulated explicitly, and he agreed in a recent conversation that abandoning the need for firm foundations may be the major shift and deepest change in natural science:

"I think that is true, and it is also true that because of the long tradition of Western science the bootstrap approach has not become reputable yet among scientists. It is not recognized as science precisely because of its lack of a firm foundation. The whole idea of science is, in a sense, in conflict with the bootstrap approach, because science wants questions which are clearly stated and which can have unambiguous experimental verification. Part of the bootstrap scheme, however, it that no concepts are regarded as absolute and you are always expecting to find weaknesses in your old concepts. We are constantly downgrading concepts that in the recent past would have been considered fundamental and would have been used as the language for questions.

"You see," Chew went on to explain, "when you formulate a question, you have to have some basic concepts that you are accepting in order to formulate the question. But in the bootstrap approach, where the whole system represents a network of relationships without any firm foundation, the description of our subject can be begun at a great variety of different places. There isn't any clear starting point. And the way our theory has developed in the last few years, we quite typically don't know what questions to ask. We use consistency as the guide, and each increase in the consistency suggests something that is incomplete, but it rarely takes the form of a well­defined question. We are going beyond the whole question­and­answer framework."

A methodology that does not use well­defined questions and recognizes no firm foundation of one's knowledge does indeed seem highly unscientific. What turns it into a scientific endeavor is another essential element of Chew's approach, which represents another major lesson I learned from him- recognition of the crucial role of approximation in scientific theories.

When physicists began to explore atomic phenomena at the beginning of the century, they became painfully aware of the fact that all the concepts and theories we use to describe nature are limited. Because of the essential limitations of the rational mind, we have to accept the fact that, as Heisenberg has phrased it, "every word or concept, clear as it may seem to be, has only a limited range of applicability." Scientific theories can never provide a complete and definitive description of reality. They will always be approximations to the true nature of things. To put it bluntly, scientists do not deal with truth; they deal with limited and approximate descriptions of reality.

This recognition is an essential aspect of modern science, and it is especially important in the bootstrap approach, as Chew has emphasized again and again. All natural phenomena are seen as being ultimately interconnected, and in order to explain any one of them we need to understand all the others, which is obviously impossible. What makes science so successful is the fact that approximations are possible. If one is satisfied with an approximate understanding of nature, one can describe selected groups of phenomena in this way, neglecting other phenomena which are less relevant. Thus one can explain many phenomena in terms of a few, and consequently understand different aspects of nature in an approximate way without having to understand everything at once. The application of topology to particle physics, for example, resulted in an approximation of precisely that kind, which led to the recent breakthrough in Chew's bootstrap theory.

Scientific theories, then, are approximate descriptions of natural phenomena, and according to Chew it is essential that one should always ask, as soon as a certain theory is found to work: Why does it work? What are its limits? In what way, exactly, is it an approximation? These questions are seen by Chew as the first step toward further progress, and the whole idea of progress through successive approximative steps is for him a key element of the scientific method.

The most beautiful illustration of Chew's attitude, for me, was an interview he gave to British television a few years ago. When asked what he would see as the greatest breakthrough in science in the next decade, he did not mention any grand unifying theories or exciting new discoveries, but said simply: "the acceptance of the fact that all our concepts are approximations."

This fact is probably accepted in theory by most scientists today but is ignored by many in their actual work, and it is even less known outside of science. I vividly remember an after­dinner discussion which illustrated the great difficulty most people have in accepting the approximate nature of all concepts, and which, at the same time, was for me another beautiful example of the depth of Chew's thinking. The discussion took place in the home of Arthur Young, the inventor of the Bell helicopter, who is a neighbor of mine in Berkeley, where he founded the Institute for the Study of Consciousness. We were sitting around the dinner table of our hosts-Denyse and Geoff Chew, my wife Jacqueline and I, and Ruth and Arthur Young. As the conversation turned to the notion of certainty in science, Young brought up one scientific fact after another, and Chew showed him through careful analysis how all of these "facts" were really approximate notions. Finally, Young cried out, rather frustrated: "Look, there are some absolute facts. There are six people sitting around this table right now. This is absolutely true." Chew just smiled gently and looked at Denyse, who was pregnant at that time. "I don't know, Arthur," he said quietly. "Who can tell precisely where one person begins and the other ends?"

The fact that all scientific concepts and theories are approximations to the true nature of reality, valid merely for a certain range of phenomena, became evident to physicists at the beginning of the century in the dramatic discoveries that led to the formulation of quantum theory. Since that time, physicists have learned to see the evolution of scientific knowledge in terms of a sequence of theories, or "models," each more accurate and comprehensive than the previous one but none of them representing a complete and final account of natural phenomena. Chew has added a further refinement to this view that is typical of the bootstrap approach. He believes that the science of the future may well consist of a mosaic of interlocking theories and models of the bootstrap type. None of them would be any more fundamental than the others, and all of them would have to be mutually consistent. Eventually, a science of this kind would go beyond the conventional disciplinary distinctions, using whatever language becomes appropriate to describe different aspects of the multileveled, interrelated fabric of reality.

Chew's vision of a future science an interconnected network of mutually consistent models, each of them being limited and approximate and none of them being based on firm foundations-has helped me enormously in applying the scientific method of investigation to a wide variety of phenomena. Two years after I joined Chew's research group I began to explore the new paradigm in several fields beyond physics-in psychology, health care, economics, and others. In doing so, I had to deal with a disconnected and often contradictory collection of concepts, ideas, and theories, none of which seemed developed sufficiently to provide the conceptual framework I was looking for. Very often, it was not even clear which questions I should ask to increase my understanding, and I certainly could not see any theory that seemed more fundamental than the others.

In this situation, it was natural for me to apply Chew's approach to my work, and so I spent several years patiently integrating ideas from different disciplines into a slowly emerging conceptual framework. During this long and arduous process it was especially important to me that all the interconnections in my network of ideas were mutually consistent, and I spent many months checking the entire network, sometimes by drawing large nonlinear conceptual maps to make sure all the concepts were hanging together consistently.

I never lost confidence that a coherent framework would eventually emerge. I had learned from Chew that one can use different models to describe different aspects of reality without regarding any one of them as fundamental, and that several interlocking models can form a coherent theory. Thus the bootstrap approach became a living experience for me not only in my research in physics but also in my much broader investigation of the change in paradigms, and my ongoing discussions with Geoff Chew have been a continuing source of inspiration for my entire work.