List of participants Preface Part I. Introduction: 1. The function of the colloquium - editorial 2. The conceptual problem of quantum theory from the experimentalist's point of view O. R. Frisch Part II. Niels Bohr and Complementarity: The Place of the Classical Language: 3. The Copenhagen interpretation C. F. von Weizsacker 4. On Bohr's views concerning the quantum theory D. Bohm Part III. The Measurement Problem: 5. Quantal observation in statistical interpretation H. J. Groenewold 6. Macroscopic physics, quantum mechanics and quantum theory of measurement G. M. Prosperi 7. Comment on the Daneri-Loinger-Prosperi quantum theory of measurement Jeffrey Bub 8. The phenomenology of observation and explanation in quantum theory J. H. M. Whiteman 9. Measurement theory and complex systems M. A. Garstens Part IV. New Directions within Quantum Theory: What does the Quantum Theoretical Formalism Really Tell Us?: 10. On the role of hidden variables in the fundamental structure of physics D. Bohm 11. Beyond what? Discussion: space-time order within existing quantum theory C. W. Kilmister 12. Definability and measurability in quantum theory Yakir Aharonov and Aage Petersen 13. The bootstrap idea and the foundations of quantum theory Geoffrey F. Chew Part V. A Fresh Start?: 14. Angular momentum: an approach to combinatorial space-time Roger Penrose 15. A note on discreteness, phase space and cohomology theory B. J. Hiley 16. Cohomology of observations R. H. Atkin 17. The origin of half-integral spin in a discrete physical space Ted Bastin Part VI. Philosophical Papers: 18. The unity of physics C. F. von Weizsacker 19. A philosophical obstacle to the rise of new theories in microphysics Mario Bunge 20. The incompleteness of quantum mechanics or the emperor's missing clothes H. R. Post 21. How does a particle get from A to B? Ted Bastin 22. Informational generalization of entropy in physics Jerome Rothstein 23. Can life explain quantum mechanics? H. H. Pattee 24. Discussion: phenomena and sense data in quantum theory D. S. Linney and C. F. von Weizsacker Index of persons Index of subjects.
List of participants Preface Part I. Introduction: 1. The function of the colloquium - editorial 2. The conceptual problem of quantum theory from the experimentalist's point of view O. R. Frisch Part II. Niels Bohr and Complementarity: The Place of the Classical Language: 3. The Copenhagen interpretation C. F. von Weizsacker 4. On Bohr's views concerning the quantum theory D. Bohm Part III. The Measurement Problem: 5. Quantal observation in statistical interpretation H. J. Groenewold 6. Macroscopic physics, quantum mechanics and quantum theory of measurement G. M. Prosperi 7. Comment on the Daneri-Loinger-Prosperi quantum theory of measurement Jeffrey Bub 8. The phenomenology of observation and explanation in quantum theory J. H. M. Whiteman 9. Measurement theory and complex systems M. A. Garstens Part IV. New Directions within Quantum Theory: What does the Quantum Theoretical Formalism Really Tell Us?: 10. On the role of hidden variables in the fundamental structure of physics D. Bohm 11. Beyond what? Discussion: space-time order within existing quantum theory C. W. Kilmister 12. Definability and measurability in quantum theory Yakir Aharonov and Aage Petersen 13. The bootstrap idea and the foundations of quantum theory Geoffrey F. Chew Part V. A Fresh Start?: 14. Angular momentum: an approach to combinatorial space-time Roger Penrose 15. A note on discreteness, phase space and cohomology theory B. J. Hiley 16. Cohomology of observations R. H. Atkin 17. The origin of half-integral spin in a discrete physical space Ted Bastin Part VI. Philosophical Papers: 18. The unity of physics C. F. von Weizsacker 19. A philosophical obstacle to the rise of new theories in microphysics Mario Bunge 20. The incompleteness of quantum mechanics or the emperor's missing clothes H. R. Post 21. How does a particle get from A to B? Ted Bastin 22. Informational generalization of entropy in physics Jerome Rothstein 23. Can life explain quantum mechanics? H. H. Pattee 24. Discussion: phenomena and sense data in quantum theory D. S. Linney and C. F. von Weizsacker Index of persons Index of subjects.
Introduction: Conceptual issues in quantum field theory Part I. Philosophers' Interests in Quantum Field Theory: 1. Why are we philosophers interested in quantum field theory 2. Quantum field theory and the philosopher Part II. Three Approaches to the Foundations of Quantum Field Theory: 3. The usefulness of a general theory of quantized fields 4. Effective field theory in condensed matter physics 5. The triumph and limitations of quantum field theory 6. Comments Discussions Part III. Does Quantum Field Theory Need a Foundation: 7. Does quantum field theory need a foundation? Part IV. Mathematics, Statistical Mechanics and Quantum Field Theory: 8. Renormalization group theory: its basis and formulation in statistical physics 9. Where does quantum field theory fit into the big picture? 10. The unreasonable effectiveness of quantum field theory 11. Comment: the quantum field theory of physics and of mathematics Part V. Quantum Field Theory and Spacetime: Introduction 12. Quantum field theory and spacetime: formalism and reality 13. Quantum field theory of geometry 14. 'Localization' in quantum field theory: how much of QFT is compatible with what we know about spacetime 15. Comments VI. 16. What is quantum field theory and what did we think it was? 17. Comments Discussions Part VII.Renormalization Group: 18. What is fundamental physics? A renormalization group perspective 19. Renormalization group: an interesting yet puzzling idea Part VIII. Non-Abelian Gauge Theory: 20. Gauge fields, gravity and Bohm's theory 21. Is the Aharonov-Bohm effect local? Discussions Part IX. The Ontology of Particles or Fields: 22. The ineliminable classical face of quantum field theory 23. The logic of quanta 24. Do Feynman diagrams endorse a particle ontology? 25. On the ontology of QFT Part X. Panel Discussion.
THE conceptual problems raised by the discovery of quantum effects have not been fully resolved after half a century. Part of the reason for this is undoubtedly to be found in the mutual ignorance which prevails between physicists and philosophers. In his book Heisenberg brings together a philosophically inclined temperament with an unrivalled knowledge of physics. The result is a book of very great interest, however much one might disagree with his conclusions. The collection of essays of which the other book is made up is intended to bring crucial conceptual problems in physics especially to the notice of philosophers. The design and intention of the collection is admirable for this is the proper way to overcome the departmentalization of interest that has left the deep conceptual problems still unresolved. Men like Heisenberg who combine philosophical temperament with scientic knowledge of great distinction are rare, and yet the difficulties can only be cleared up by the application of philosophical techniques of analysis to problems which are an intimate and difficult part of physics. A great deal of the interest of Heisenberg's book lies in the very comprehensive account he gives of the origin and growth of the Copenhagen school, and the way the new phenomena forced a largely unwelcome picture of nature upon Bohr and his friends. The most important chapter from a philosophical point of view is that in which Heisenberg defends this interpretation against the attacks to which it has been subjected. The essence of his argument for the interpretation can be summed up in two propositions. (i) The Copenhagen interpretation of physical theory, which depends upon the acceptance of the so-called Principle of Complementarity, is an inevitable and final interpretation. The reason for this is that there are only two possible general models for understanding given physical phenomena; a particle model or a wave model. These are exhaustive and exclusive because the former depends upon discontinuous and the latter upon continuous (using substance here in the traditional philosophical sense). If we find, as we do, that the two fundamental constituents of the universe, matter and radiation, each exhibit two classes of phenomena, one explainable only on a particle model and one on a wave model, then we are compelled to adopt a complementarity hypothesis and give up the idea of finding a single and uniform model for the understanding of phenomena. There are only two kinds of models; they are mutually exclusive; both are required; hence we either despair before an insoluble problem or adopt the Copenhagen interpretation. (2) Any serious criticism of this interpretation must offer an alternative
The foundations and meaning of quantum theory became a central issue to Albert Einstein and Niels Bohr since the onset of their impassioned debate in the 1920s, enriched by the contributions of many other distinguished scientists and philosophers.The questions are not settled down at all, despite the great achievements of the theory, its impressive accordance with experiment and predictive power.The fundamental and technological applications range from cosmology to biology, with the development of invaluable instruments and the design of new materials.Is quantum mechanics a complete or an incomplete theory?Is there an objective reality independent of the observer or is the reality created by the measurements?Are hidden-variable theories justifiable?Is there a quantum theory founded in a local-causal and non-linear approach that formally contains the orthodox linear theory as a special case?Can such a formulation unify classical and quantum physics?Are Heisenberg's uncertainty relations valid in all cases?Here, the subject is addressed as an adaptation of our contribution to the Colloquium "Quantal aspects in Chemistry and Physics.
For many years the physical interpretation of quantum theory has been dominated by the “wave-particle duality” attitude of the “Copenhagen school.” This point of view is eloquently described in Bohr's collection of essays on the subject. Despite persistent concerns with apparent paradoxes and limitations to this interpretation (as exemplified by Schrodinger's cat, the paradox of Einstein, Podolsky and Rosen, among others), the Copenhagen view persists de facto in the daily life of the modern physicist. Traditional quantum theory has so successfully explained such a vast amount of data in atomic and molecular physics, solid state physics (and to a lesser extent, elementary particle physics) that little doubt can exist concerning its essential validity. As a consequence of the overwhelming practical success of the “Copenhagen interpretation, ” the latter has acquired the status of dogma. For many years, therefore, most physicists have found it expedient to relegate the puzzling aspects of the theory to philosophers, and mathematicians. Nevertheless, a persistent interest in this subject has produced a significant and fascinating literature, reviewed by Jammer. In recent years, concerns over the proper meaning to be ascribed to quantum theory have produced an increasingly deep and incisive series of investigations. These investigations fall generally into two categories: either (1) discussion of the philosophical content of the theory, or (2) analyses of the mathematical variants of the theory and their connection with differing interpretational schemes. Physicists tend to be detached from a commitment to philosophical issues, because of their realization of the transient character of the meanings attached to theories of the day. As a simple illustration of this we can mention the profound differences between nonrelativistic and relativistic quantum mechanics.
Part I. Niels Bohr. Communications delivered to the Royal Danish Academy of sciences and letters, October 3, 1985 (edited by E. Dal). Niels Bohr and The Royal Danish Academy of Sciences and Letters (B. Strmgren). Epistemological considerations (H.B.G. Casimir). Part II. The Lesson of Quantum Theory. Proceedings of the Niels Bohr centenary symposium, October 4-7, 1985 (edited by J. de Boer and O. Ulfbeck). The Lesson of Quantum Theory. Measurement in quantum theory and the problem of complex systems (P.W. Anderson). Quantum mechanics at the macroscopic level (A.J. Leggett). Strange quantum numbers in condensed matter and field theory (J.R. Schrieffer). The study of the nucleus as a theme in contemporary physics (B.R. Mottelson). ``Complementarity'' between energy and temperature (J. Lindhard). Radiation by uniformly moving sources (V.L. Ginzburg). Does elementary particle physics have a future? (S.L. Glashow). Observability of quarks (J.D. Bojrken). The transformation of elementary particle physics into many-body physics (L. Van Hove). Physics in terms of difference equations (T.D. Lee). Some lessons of renormalization theory (A.S. Wightman). Particles, fields and now strings (S. Weinberg). Collective and planetary motion in atoms (R.S. Berry). Unity of Knowledge. The origin and evolution of large-scale structure in the universe (W.L.W. Sargent). Molecular replication and the origins of life (L.E. Orgel). Physics, biological computation and complementarity (J.J. Hopfield). Complementarity in linguistic observation, description and explanation (W.U. Dressler). Niels Bohr. Great connections come alive: Bohr, Ehrenfest and Einstein (M.J. Klein). Niels Bohr and nuclear weapons (M. Gowing). Niels Bohr: The man and his legacy (J.A. Wheeler). Mellem Spog og Alvor: Personal recollections about Niels Bohr (H.B.G. Casimir). Part III. Jest and Earnest. AAddresses presented at the evening gathering in Ny Carlsberg Glyptoteket, October 7, 1985. (edited by J. de Boer and O. Ulfbeck). Parentesen (A. Aaboe). Truth and clarity (R. Peierls). Niels Bohr, the quantum and the world (V.F. Weisskopf).
Acknowledgements Part I. Measurment in Quantum Theory: 1. Role of the observer in quantum theory 2. Approximate measurement in quantum mechanics with Mary H. Fehrs 3. Proposed neutron interferometer test of some non-linear variants of wave mechanics 4. Desiderata for modified quantum mechanics 5. Filters with infinitely many components 6. Proposed neutron interferometer observation of the sign change of a spinor due to 2? precession with Michael A. Horne Part II. Quantum Entaglement and Nonlocality: 7. Experimental consequences of local hidden-variable theories 8. An exposition of Bell's theorem 9. Contextual hidden variables theories and Bell's inequalities 10. Controllable and uncontrollable nonlocality 11. Events and processes in the quantum world 12. An exchange on local beables: comment on Bell's theory with Michael A. Horne and John F. Clauser 13. Physical and philosophical issues of the Bohr-Einstein debate Part III. Complex Systems: 14. The methodology of synthesis: parts and wholes in low energy physics 15. Some proposals concerning parts and wholes 16. The non-existence of a principle of natural selection: reply to Sober Part IV. Time: 17. Towards a revision of the protophysics of time 18. The transient now Part V. The Mental and the Physical: 19. Quantum physics and the philosophy of Whitehead 20. Reflections on the philosophy of Bohr, Heisenberg and Schroedinger 21. Wave-packet reduction as a medium of communication with Joseph Hall, Christopher Kim, and Brian MecElroy Index.