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Nobel Prize winner Werner Heisenberg s classic account explains the central ideas of the quantum revolution, and his celebrated Uncertainty Principle The theme of Heisenberg s exposition is that words and concepts familiar in daily life can lose their meaning in the world of relativity and quantum physics This in turn has profound philosophical implications for the nature of reality and for our total world view


10 thoughts on “Physics and Philosophy: The Revolution in Modern Science

  1. Robert Robert says:

    REVIEW OF THE BOOK AS A WHOLEReally, the title should have warned me that I was unlikely to get along with this book but it doesn t actually say, Physics and Metaphysics I have very little time for metaphysics it s day is long since past couple of millenia, at least and it is really only of historical interest to those concerned with understanding nature Far too much of the book is spent on either comparing quantum mechanics QM with Western metaphysics or pondering unanswerable conund REVIEW OF THE BOOK AS A WHOLEReally, the title should have warned me that I was unlikely to get along with this book but it doesn t actually say, Physics and Metaphysics I have very little time for metaphysics it s day is long since past couple of millenia, at least and it is really only of historical interest to those concerned with understanding nature Far too much of the book is spent on either comparing quantum mechanics QM with Western metaphysics or pondering unanswerable conundrums, like, does anything exist when it isn t being observed and what type of reality is really real What science does with increasing precision over time is attempt to explain the contents and behaviour of nature, not whether it is dogmatically objective or some other type of objective or subjective or, who knows, subjunctive or conjunctive or metastatically cancerousThis comparison with western metaphysics is as profitless as the later 80s 90s fad for comparison with eastern philosophy Metaphysics, regardless of hemisphere did not lead to nuclear reactors and smart phones, so any apparent correspondences are vague, incomplete and of no practical use.Heisenberg seems inconsistent at times, which is a bit naff in a book on science or philosophy, let alone both For instance, he states categorically that no human observer is actually necessary in QM but later seems to tacitly assume the opposite He s also wrong about a few things, but only in the light of 50 years worth of further scientific investigations.I also don t know who the intended audience is he assumes quite a bit of knowledge of both physics and metaphysics certainly too much of the former for a non physicist audience now or then and too much of the latter for present day non philosophy students.Probably the only really valuable insight I got from the book was the point that General Relativity isn t a limiting case or approximation of or to any other physical theory it famously can t be integrated into any current quantum theory but it can t be derived from any other classical theory either, not can any other classical theory be derived from it It just stands there in majestic aloofness It has done since it was first published and still does now.The other segment of interest to me was the final chapter on the influence of science in general and modern physics in particular on contemporary society here s where I think general philosophical thought might profitably be focused, along with close examination of recent history.The book also seems badly organised why does the chapter on alternatives to the Copenhagen Interpretation of QM not follow immediately after the chapter on the Copenhagen Interpretation itself, for instance I find it difficult to recommend this book to anybody if you want to become familiar with the central concepts of QM, The Character of Physical Law by R.P Feynman is enormously better Einstein s own book is a much better introduction to Relativity theory especially if you can remember school algebra If you are interested in the philosophy of science, this book won t help It s too out of date to work as an introduction to the state of contemporary fundamental physics The only bits that seem to remain really relevant are the thoughts about the use of language in science and the thoughts on science s impact on society at large.Below the lineor less chapter by chapter thoughts whilst reading.___________________________________________________________________________Insufficient room in the status update field so I m gonna have to post my thoughts here as I go along.Despite the lack of mathematics, I already can t recommend this for non physicists I think they d be terribly confused and horribly lost by the end of Chapter 2 On the other hand, this might be very good for current physics undergrads who ve done an atomic physics course already.Interesting errors and confusions in Chapter 3 Conservation of energy Heisenberg states that initially this was believed to be true only statistically for quantum systems but in fact turned out to be exactly true always This is not correct conservation of energy can only be said to hold to the accuracy given by fanfare The Heisenberg Uncertainty Principle One of the bizarre consequences of this is the phenomenon of quantum tunneling, which was unknown at the time of publication.Heisenberg states that quantum mechanical experiments consist of three parts, an initial set up in terms of classical physics, an unobservable part only describable in terms of what we would now call the probability wave function, and a measurement only describable in terms of classical physics Only the middle part of this is correct it is entirely possible to describe an experimental set up in quantum terms and also the measurement of the result in quantum terms, too The middle bit is indeed not describable in any normal sense Take the photon double slit experiment The emission of the photons can be described quantum mechanically but so can their reception at the detector if you use photo multiplier detectors, for example.Ah I hear you cry, but the real observation is by the human eye, when the flash from the photo multiplier hits the retina Sorry the optic nerve is a receptor of quanta, too The whole system is describable quantum mechanically.Heisenberg then goes on toor less follow my argument in a vague way It s enormously easier to make it precise in the light of half a century s technological advances And here s something really important that we agree on The human observer is not in any way an essential part of the system The idea that the entire universe stopped being just a cloud of probabilities the day a sufficiently astute observer appeared is not in any way required by or implicit in the Copenhagen Interpretation.and we re only about 1 6th the way throughChapter 4 Waffling comparison of ancient Greek philosophy and quantum mechanics The most important thing here is the bit where he explains the difference i.e QM is based on experiment where as ancient Greek philosophy is based on yabbering on without having a clue.Some interesting points are raised, though What s a particle is a very hard question to answer in QM It s a probability wave packet, isn t a very good answer it s a form of energy is better except, what s energy Today you might get, it s a resonance in a field Leading straight on to, What s field Well, it s something emitted by particles that controls how they interact with each other This is just wave particle duality all over again, with waves disguised as fields.He also expresses the views that the ultimate quantum theory would take the form of a single equation that would yield solutions representing the fundamental particles and the forces between them and that in fact there will turn out to only be one kind of particle that is truly fundamental The former is the approach taken by current Guess the Lagrangian approaches to the problem and the latter is adopted in string theories all 10 500 of them.Chapter 5 Physics vs Metaphysics Physics wins Or summat.Is there such a thing as objective reality Yes OK I can agree with that But I don t really understand when he starts trying to distinguish between types of objective reality I mean, in science you get successive different theories of the behaviour of objective reality but that doesn t seem to be what is being discussed It doesn t seem to be the old causality vs indeterminacy chestnut, either Colour me baffled and not caring much, either.Chapter 6 Relation of QM to other sciences.Here Heisenberg seems to be groping after a coherent general philosophy of Emergent Behaviour without quite getting there seemsin the Emergent camp than the Reductionist camp, anyway One interesting comment is that biology requires physics chemistry plus history The history allows for evolutionary theory by way of genetics But one could view history as actually being emergent from physics by way of the 2nd Law of Thermodynamics, a connection he does not make.He also discusses the main theories of physics in relation to each other Newtonian mechanics is an approximation to Special Relativity which assumes an infinite speed of light It is also an approximation to QM assuming an infinitely small Planck s Constant Thermodynamics can be understood as a statistical theory of particles and can be derived from either QM or Newton s Laws But General Relativity sits there looking lonely and mean, yet beautiful, and defying all attempts to integrate it into any other aspect of physics as any kind of limiting case or emergent theory.The error regarding the description of QM experiments in terms of classical physics is repeated.Chapter 7 Relativity.Einstein s book will give you a clearer understanding of Special Relativity and the Principle of Equivalence but you will need to know some school algebra On the other hand, that is a whole book about the same length as this one, not one lecture chapter A point re iterated through out the chapters so far is the use by physicists of ordinary language in specialised ways This is essential as it turns out that ordinary concepts like space and time, on closer examination turn out to be muchsubtle and complex phenomena than is readily appreciated in daily life I think one of the later chapters goes into this in depth.Heisenberg emphasises that General Relativity is not on a strong experimental footing it wasn t then but it is now Some of the cosmological questions raised have been answered, others haven t and recently new and evenfreaky ones have been found.Chapter 8 seems as far as I can tell to come down to, Does the particle exist when you re not looking Well, that question isn t anyanswerable than the question in classical physics, Does that brick exist when you re not looking Looking here means doing anything in order to verify the existence of the particle brick Assuming something doesn t exist when you re not looking is essentially Solipsistic Cartesian and denied by the persistence of macroscopic objects.The Everett Many Worlds Interpretation hadn t been thought up yet, so isn t discussed The main focus is on hidden variables notions.I m getting impatient for this to be overThe remainder A chapter surveying the contemporary state of sub atomic physics Of course, it s out of date Most interesting now for it s speculation that the number of types of truly elementary particles will drop, possibly to one What happened between then and now is that the number went up for some time, then dropped again as quark theory was verified and recently went up by one again with the discovery of a Higgs like boson Given the current experimental evidence hypotheses theories in cosmology, one would think the number willlikely go up rather than down in the immediate future.Chapter on language in science and physics in particular in relation to every day language Perhaps the most obvious pervasive theme of the book.Final chapter on the effects of modern physics and nuclear physics in particular on society at large and it s mode of thought More interesting than almost the entirety of the rest of the book


  2. Martina Martina says:

    This has got to be one of the most singular reading experiences ever Ever Heisenberg s book is so unusual, refreshing and unique I m not even sure on which shelf to put it The funny thing is, this book is not so much about physics, or about philosophy, for that matter Perhaps aapt title would be The life and times of Werner H It reads like a novel, and, in a way, it is a novel I would call it a novelized autobiography , for Werner talks about his life, his work, his thoughts in a This has got to be one of the most singular reading experiences ever Ever Heisenberg s book is so unusual, refreshing and unique I m not even sure on which shelf to put it The funny thing is, this book is not so much about physics, or about philosophy, for that matter Perhaps aapt title would be The life and times of Werner H It reads like a novel, and, in a way, it is a novel I would call it a novelized autobiography , for Werner talks about his life, his work, his thoughts in a series of episodes, referencing many political and historical events and famous persons he had a chance to meet It s all written in a lively style, which is quite unexpected for someone who is deemed to be a great physicist of the 20th century and physicists are supposed to have dull writing styles P As most people, I m curious about the lives of people who had done something worthwhile It s a benevolent kind of curiosity that drives one to ask questions about the person behind that big name a person with likes, dislikes and quirks, a person who wasn t born with an innate knowledge of his or her discipline, but who had to work to get where he or she is at And in that regard, Physics and philosophy is a great accomplishment, because we have a chance to get to know the real Werner Heisenberg Not just the guy who founded matrix mechanics and gave the world the uncertainty principle, but a nature lover with a penchant for music, who had engaged in the works of a youth organization and who had no qualms whatsoever to work as a lumberjack just to alleviate the financial strain from his father But all this information islike a subtext of the book Heisenberg, for the most part, concentrates on his studies and professional career, and doesn t talk about physics in a textbook manner Rather, he talks about the problems that preoccupied him at the time, with just enough hints so that readers versed in physics know what he s saying, and that the laymen readers don t get bored But for me, the biggest thing Werner accomplished with this book, is the portrayal of the zeitgeist in his country in his youth and later on in the world No, I m not going to romanticize the time he lived in We all know about the gruesome things that had happened time frame Heisenberg was twelve at the beginning of WWI I m referring to the general climate after the 1st World War It was a time when people read , played music together by and by, Heisenberg was an excellent piano player , and were not afraid to dabble in things that weren t their specialty Almost everyone had interests on the side, and pretty substantial ones like reading philosophy books and even young people were not shy to discuss their personal thoughts on this or that matter I was amazed at how perceptive many of those young people were at the time according to the conversations Heisenberg had relayed in the book To make things evenexciting, it was a dawn of a new time, the birth of atomic and molecular physics, quantum mechanics, and relativistic physics So it s not all together surprising that many of the scientists Heisenberg had encountered, even during his university years, ended up as Nobel prize winners We meet a whole host of them throughout the book, and somehow, we get to know them as people, or at least Heisenberg s impression of them His teacher Sommerfeld, and his university colleague Pauli then Bohr himself, Einstein, Schr dinger, Dirac Just reading about Werner meeting all these people especially from today s perspective is totally mind blowing It s true that Heisenberg had edited out a large quantity of physics talk with them, but he included other conversations which were not so much on philosophy, butabout life and beyond Those conversation revealed much about the participants They even managed to endear Niels Bohr to me, and by that alone, you can tell how persuasive Heisenberg s writing is view spoiler Just Niels view on war, and Denmark really tugged at my heartstrings i hangs head i hide spoiler I also loved that we got deeper insight into Heisenberg s own thinking processes His account on how he got to the groundbreaking idea of the uncertainty principle should be mandatory reading view spoiler Fun fact at the same time, Bohr was on a skiing vacation in Norway, where he developed his complementarity idea hide spoiler The book is also incredibly witty, especially when Heisenberg paints humorous scenes view spoiler Those who know to what I m referring When Schr dinger visited Bohr in his home in Copenhagen Chapter 6 , they had heated debates concerning quantum mechanics that went on for days and nights But when Schr dinger got down with fever from all those exertions, Mrs Bohr made him tea, gave him cakes, and tucked him in bed, while Niels sat by his bedside, evangelizing his theories Surely you must see Yeah, you know that scene, and so does my whole neighborhood They could hear me laughing hide spoiler And it s chock full of memorable quotes if I started to quote now, I would probably use up all my characters If you have a chance to read this book, do it You won t be sorry


  3. Austin Wright Austin Wright says:

    Physics and Philosophy by Werner Heisenberg ReviewPhysics and Philosophy is a book published in 1962 by Werner Heisenberg, a giant of modern physics , about the theory of Quantum Mechanics and its philosophical implications This book is certainly best read with prior knowledge of some classical and some quantum physics I actually read it knowing little or nothing about quantum physics, and the parts that described in detail the physics seemed technical and hard to understand, yet still i coul Physics and Philosophy by Werner Heisenberg ReviewPhysics and Philosophy is a book published in 1962 by Werner Heisenberg, a giant of modern physics , about the theory of Quantum Mechanics and its philosophical implications This book is certainly best read with prior knowledge of some classical and some quantum physics I actually read it knowing little or nothing about quantum physics, and the parts that described in detail the physics seemed technical and hard to understand, yet still i could make sense partly of most of it But then I took a course in quantum cryptography and looking back at it it all makes well enough sense So knowledge of physics is very highly recommended As far as the philosophy goes i found it much easier to understand as he talks about high level concepts in ancient greek and renaissance thinking If fully understood this book can really help to inform our perception of reality and how quantum mechanics has changed that Forever we have imagined the world as objectively real that whether or not we observe something it is the same, that one thing must be in one single place at any given time, that time and space are infinitely divisible and constant This book uses the proven theories of quantum mechanics and relativity to help break those notions on what reality truly is and it is this aspect of the book that i find most enthralling It uses logic, experimental evidence, and facts to undermine objective reality and replace it with a weird, alien view of everything This book is incredibly importantso for philosophers thank physicists because it breaks many core assumptions down and replaces them with new and strange, yet experimentally proven results that, taken to logical fruition, produce the likes of Schrodinger s Cat which is in a superposition of dead and alive, that is to say, both dead and alive simultaneously It are these ideas that radically change the basis of much thought ever since the beginning of human history.I recommend this book only if you have at least a rudimentary understanding of some physics and algebra, and if you are open minded enough to question the very core beliefs of reality, because that can certainly be alot to fully grasp Otherwise this book can seem very technical when it talks about physics, and strange about philosophy But if you can understand and accept the statements made here then it is an absolute must read provoking some deep insight into some of the largest and most fundamental questions of reality


  4. Cassandra Kay Silva Cassandra Kay Silva says:

    Heisenberg the famous Nobel Prize winner takes us through the building up of our current understanding of Quantum Reality and the physics that lead up to this He gives a good discussion of the Uncertainty principle of which he is so famous for and how this will impact the future of physics and how we see the world The title is misleading however, don t expect much philosophy out of this book, and of course it was written when many ideas of modern physics were not even hardly fleshed out yet I Heisenberg the famous Nobel Prize winner takes us through the building up of our current understanding of Quantum Reality and the physics that lead up to this He gives a good discussion of the Uncertainty principle of which he is so famous for and how this will impact the future of physics and how we see the world The title is misleading however, don t expect much philosophy out of this book, and of course it was written when many ideas of modern physics were not even hardly fleshed out yet I think this makes it interesting to see where he though physics might go, and compare this to the current state It makes you wonder what he would have though of the work going on in Geneva, and how he would have looked at some of the physics of today


  5. Amy Amy says:

    Some Knots Have Knotted LimbsToward the end of Physics and Philosophy Werner Heisenberg presciently mentions the incompatibility of quantum mechanics with relativity and the need for coherent concepts that allow for both theories without mathematical inconsistencies Today unified field theories of quantum gravity that attempt to reconcile quantum mechanics with relativity are being explored by physicists in proposals like string theory Heisenberg also mentions that the physicists of his time w Some Knots Have Knotted LimbsToward the end of Physics and Philosophy Werner Heisenberg presciently mentions the incompatibility of quantum mechanics with relativity and the need for coherent concepts that allow for both theories without mathematical inconsistencies Today unified field theories of quantum gravity that attempt to reconcile quantum mechanics with relativity are being explored by physicists in proposals like string theory Heisenberg also mentions that the physicists of his time were discovering elementary particles by experimenting with high speed particle accelerators which he calls big accelerating machines , referencing a machine in Geneva, what we now know as the operational Large Hadron Collider at CERN that is testing aspects of string theory by attempting to recreate conditions of the universe during the Big Bang Heisenberg s discerning comments about the future are not surprising given the intricate attention he pays to contemporary and historical conditions through contextualizing quantum mechanics in relation to everything from Einstein s relativity Heisenberg s uncertainty principle rebuts Einstein s notion that probability cannot be expressed in physical reality to atomic weaponry to Western philosophical thought Descartes, Berkeley, and Kant.Heisenberg relates quantum theory to the first conceptions of atomic science, starting with Thales, who says that water is the fundamental substance of reality After Thales, Anaximander says the fundamental substance is ageless and eternal but nothing that can be known his student Anaximenes says the fundamental substance is air Heisenberg notes that Hereclitus argument for fire being the fundamental substance comes closest to his contemporary understanding of atomic science if only the word, fire, was replaced with the word, energy It was Empedocles who shifted the debate from monism to pluralism by proposing the fundamental substance could not be one substance but instead the four basic elements When Anaxagoras proposed that matter is composed of small seeds and that all change is caused by mixture and separation, he was just one step to the concept of the atom, which occurred with Leucippus and Democritus proposing that the smallest unit of matter is finite, eternal, and indestructible and that motion is made possible by the empty space between these units Plato then articulated a theory of matter that combined Democritus atomism with the teachings of Empedocles and Pythagoras who inspired schools of ritualistic Dionysian number theorists who took religious oaths to the tetraktys, the fourth triangular number of 10 to propose that the smallest units of matter are mathematical forms, about which Heisenberg comments, here it is quite evident that the form isimportant than the substance of which it is the form Like a poem Describing his understanding of the structure of language, Heisenberg quotes from Goethe s Faust, where Mephistopheles tells the student that while formal education instructs that logic braces the mind in Spanish boots so tightly laced and that even spontaneous acts require a sequential process one, two, three , in truth, the subtle web of thought Is like the weaver s fabric wrought, One treadle moves a thousand lines, Swift dart the shuttles to and fro, Unseen the threads unnumber d flow, A thousand knots one stroke combines In addition to the swift darts and unseen threads of the imagination science must also be based on logic, open to pattern and swerve Yet Heisenberg acknowledges there is no adequate language for quantum theory, which suggests that any novel science must concurrently create a novel language poems where a thousand knots one stroke combines


  6. Mengsen Zhang Mengsen Zhang says:

    ok it s a great book I m giving three stars based on my personal experience with this book I do not fully understand his composition of this book I have to ignore many passages to have a holistic impression of what he s arguing about.Based on what I understand, I would give this book another name Language and Dispute the evolution of human knowledge I would say it sabout language and reality rather than physics and philosophy The most charming part of this book to me, is his ana ok it s a great book I m giving three stars based on my personal experience with this book I do not fully understand his composition of this book I have to ignore many passages to have a holistic impression of what he s arguing about.Based on what I understand, I would give this book another name Language and Dispute the evolution of human knowledge I would say it sabout language and reality rather than physics and philosophy The most charming part of this book to me, is his analysis of the notion of matter or atom, or the essence of objects about how it evolves from ancient philosophy to classical physics and then to modern physics He compared the representation of reality with mathematical language and natural language The use of language is stabilized by the connection between words, but what a word itself is representing is very unstable alright..uncertain if we like As a description of the world propagates via linguistic representation, the abstraction and precision of the description becomes lost person by person, or generation by generation until, some how, modern experimental apparatus widen the spectrum of events can be observed, and save the mental effort for people to achieve that order of abstraction I also found the bonus read on science and religion quite interesting Especially the little story about the debate between Heisenberg, Dirac and Pauli over the relationship between science and religion I love Pauli the most It is a miniature reflection of the book most likely to be unintended Apparently, among these three giants of quantum physics, there was a very uncertain representation of events by the word religion or God Some of them referred to a description of reality, while others referred to the utility of that description And it is fun to see them arguing about the symbols rather the reality they each have in mind


  7. Anna Hiller Anna Hiller says:

    This is really a book about physics that only lightly touches on philosophy A good reason to read it would be to understand why it is that 20th century physics totally changed the world, something that I think is generally forgotten these days in spite of our ab use of technology, the prodigal wunderkind of the advances in science over the last 200 years or so The thing to remember about Heisenberg s book is that it was written at the height of the Cold War, and therefore beneath the shadow o This is really a book about physics that only lightly touches on philosophy A good reason to read it would be to understand why it is that 20th century physics totally changed the world, something that I think is generally forgotten these days in spite of our ab use of technology, the prodigal wunderkind of the advances in science over the last 200 years or so The thing to remember about Heisenberg s book is that it was written at the height of the Cold War, and therefore beneath the shadow of nuclear weapons in fact, he states that right on page one And so his conclusion with its conflicting apocalyptic utopian possibilities for the future is very much a product of his time Heisenberg s style is very indirect and hesitant, kind of surprising considering his prominence in the field Altogether informative, if a bit dated Lindley s introduction in the 2007 edition is fantastic, and makes up for the timewarp


  8. Bob Nichols Bob Nichols says:

    Heisenburg traces philosophical thought from Greeks permanence versus change ultimate elements of reality to Descartes the partition of mind and matter to Newton classical physics mechanics These philosophical ideas have, Heisenburg writes, formed the way we see the world and the language we use to describe it.Heisenburg argues that ideas and language pertaining to the empirical world are not adequate to deal with the realities of quantum physics ultimate reality as energy, out of which Heisenburg traces philosophical thought from Greeks permanence versus change ultimate elements of reality to Descartes the partition of mind and matter to Newton classical physics mechanics These philosophical ideas have, Heisenburg writes, formed the way we see the world and the language we use to describe it.Heisenburg argues that ideas and language pertaining to the empirical world are not adequate to deal with the realities of quantum physics ultimate reality as energy, out of which sub particles are formed, the behavior of which can be determined only in terms of probability Nor are classical descriptions adequate to deal with the realities of relativity theory light as a universal constant the stretching, contracting and linking of space and time the equivalence of mass and energy Heisenburg believes that the spread of science around the world can deepen and widen Western philosophical thought that confines our way of seeing the world He is hopeful that new ways of thinking will also unify cultural differences and eliminate arms in the age of nuclear weapons Based on what Heisenburg writes, the starting point for a new worldview might have energy as the ultimate reality, that energy is motion, motion creates counter motion, that such interactions are rearrangements of energy and matter and that change and transformation is perpetual Might this view have implications for our philosophical understanding Are, for example, freedom the movement of energy and matter life s free movement to seek objects of sustenance to temporarily overcome entropy equality balance and the elimination of energy power differentials and dialectical processes movement, counter movement, balance embedded in the physics of energy and matter The Kindle edition was filled with many typographical errors and the introduction to the book was difficult Energy is in fact the substance from which all elementary particles, all atoms, and therefore all things are made, and energy is that which moves Energy is a substance, since its total amount does not change, and the elementary particles can actually be made from this substance A question remains about the nature of motion whether its source is external gravitational effects in warped space time internal atoms in motion dissipation of heat , or both


  9. Daniel Prasetyo Daniel Prasetyo says:

    The essence of quantum physics from one of it s founder Mind blowing..


  10. Oscar Despard Oscar Despard says:

    This slender volume is a superb introduction to quantum theory, as explained by one of its discoverers Heisenberg has aimed this discursive essay at the general reader, with the aim of explaining subatomic mechanics in natural language insofar, Heisenberg makes clear, as that may be possible In doing so, he avoids the delight in obscurity that characterises some superficial descriptions of that theory though this book stimulates the reader s mind, it does not overwhelm it.Nevertheless, Heisen This slender volume is a superb introduction to quantum theory, as explained by one of its discoverers Heisenberg has aimed this discursive essay at the general reader, with the aim of explaining subatomic mechanics in natural language insofar, Heisenberg makes clear, as that may be possible In doing so, he avoids the delight in obscurity that characterises some superficial descriptions of that theory though this book stimulates the reader s mind, it does not overwhelm it.Nevertheless, Heisenberg does not hesitate to elucidate the fundamental changes that modern physics necessitates in our engrained perception of reality He explains without condescension how such ideas will interact with pre existing cultures, and he graciously tracks the development of natural science through the centuries back to pre Socratic philosophers, from the relatively prominent, like Demosthenes, to theobscure, like Anaxagoras His grace is equalled by his honesty He acknowledges the flaws and benefits of Cartesian metaphysics, which allowed classical physics to flourish but is primarily responsible for the ontology that we must overturn to understand quantum mechanics He also comments on the usefulness of the Kantian notion of the a priori status of Newtonian physics he counsels against any hope to escape them entirely since they are the only basic concepts by which we can interpret the natural world Therefore, he holds them to be in a sense a priori, in spite of the fact that their status as objective truth, and indeed the very idea that such truth is possible, has been toppled by his own uncertainty principle.Of course, his uncertainty principle is the startling discovery at the heart of this book, and he clearly refutes any classical reinterpretations of it, but he is very modest in his references to it Apart from off hand mentions of jokes made by Bohr, or disputes with Einstein, one could read this book without realising that its author had won the Nobel Prize, or in fact that he had articulated the principle of uncertainty that he so often cites This decision not to mention details he deems unnecessary exemplifies the understatement and concision that characterise this book, which it would almost seem false to flatter by calling elegance The pleasantness of the writing is underlined by its lack of pretension Aware as Heisenberg is of the wider implications of quantum theory, he is also reluctant to claim too much for it Nevertheless, his musings on the unification between atomic physics and chemistry, and on whether such a development is possible in biology, are well worth reading If I am to avoid this review becoming as long as the book about which it is, I must conclude This erudite essay succeeds in its stated goal of explaining the concepts of quantum mechanics to the general reader It does so without direct use of mathematical symbols, a particular challenge for such a counter intuitive area of science It was a fascinating read that I would highly recommend to anyone interested and confused, which so often coincide, in the world described by quantum theory