The Birth of String Theory by Cappelli et al. tells the story of the beginnings of string theory and of the evolutionary process it has undergone from its origins in S-matrix theory to its current status as a candidate unification theory. The book is intended for an audience of students and researchers in physics, as well as historians and philosophers of science with some background in quantum field theory.In the 50s and early 60s, theoretical particle physics focused on formulating a (...) theory to explain the strong interactions. Due to issues with the application of perturbative quantum field theory to the strong interactions, theoretical particle physicists shifted their attention to Heisenberg’s ‘S-matrix’ theory, which focused solely on observable quantities. This endeavour led in 1968 to the breakthrough of the famous ‘Veneziano amplitude’, which along with the Dolen–Horn–Schmid duality between the s- and the t-channels led to the dual resonance model . Following Ve .. (shrink)

This is the final draft of Chapter 4 of the Volume 'The Birth of String Theory' edited by A. Cappelli, E. Castellani, F. Colomo, and P. Di Vecchia, Cambridge University Press, forthcoming.

We demonstrate that the quantum-mechanical description of composite physical systems of an arbitrary number of similar fermions in all their admissible states, mixed or pure, for all finite-dimensional Hilbert spaces, is not in conflict with Leibniz's Principle of the Identity of Indiscernibles (PII). We discern the fermions by means of physically meaningful, permutation-invariant categorical relations, i.e. relations independent of the quantum-mechanical probabilities. If, indeed, probabilistic relations are permitted as well, we argue that similar bosons can also be discerned in all (...) their admissible states; but their categorical discernibility turns out to be a state-dependent matter. In all demonstrated cases of discernibility, the fermions and the bosons are discerned (i) with only minimal assumptions on the interpretation of quantum mechanics; (ii) without appealing to metaphysical notions, such as Scotusian haecceitas, Lockean substrata, Postian transcendental individuality or Adamsian primitive thisness; and (iii) without revising the general framework of classical elementary predicate logic and standard set theory, thus without revising standard mathematics. This confutes: (a) the currently dominant view that, provided (i) and (ii), the quantum-mechanical description of such composite physical systems always conflicts with PII; and (b) that if PII can be saved at all, the only way to do it is by adopting one or other of the thick metaphysical notions mentioned above. Among the most general and influential arguments for the currently dominant view are those due to Schrodinger, Margenau, Cortes, Dalla Chiara, Di Francia, Redhead, French, Teller, Butterfield, Giuntini, Mittelstaedt, Castellani, Krause and Huggett. We review them succinctly and critically as well as related arguments by van Fraassen and Massimi. (shrink)

In Dirac-Bergmann constrained dynamics, a first-class constraint typically does not _alone_ generate a gauge transformation. By direct calculation it is found that each first-class constraint in Maxwell's theory generates a change in the electric field E by an arbitrary gradient, spoiling Gauss's law. The secondary first-class constraint p^i,_i=0 still holds, but being a function of derivatives of momenta, it is not directly about E. Only a special combination of the two first-class constraints, the Anderson-Bergmann -Castellani gauge generator G, leaves (...) E unchanged. This problem is avoided if one uses a first-class constraint as the generator of a _canonical transformation_; but that partly strips the canonical coordinates of physical meaning as electromagnetic potentials and makes the electric field depend on the smearing function, bad behavior illustrating the wisdom of the Anderson-Bergmann Lagrangian orientation of interesting canonical transformations. The need to keep gauge-invariant the relation dot{q}- dH/dp= -E_i -p^i=0 supports using the primary Hamiltonian rather than the extended Hamiltonian. The results extend the Lagrangian-oriented reforms of Castellani, Sugano, Pons, Salisbury, Shepley, _etc._ by showing the inequivalence of the extended Hamiltonian to the primary Hamiltonian even for _observables_, properly construed in the sense implying empirical equivalence. Dirac and others have noticed the arbitrary velocities multiplying the primary constraints outside the canonical Hamiltonian while apparently overlooking the corresponding arbitrary coordinates multiplying the secondary constraints _inside_ the canonical Hamiltonian, and so wrongly ascribed the gauge quality to the primaries alone, not the primary-secondary team G. Hence the Dirac conjecture about secondary first-class constraints rests upon a false presupposition. The usual concept of Dirac observables should also be modified to employ the gauge generator G, not the first-class constraints separately, so that the Hamiltonian observables become equivalent to the Lagrangian ones such as the electromagnetic field F. (shrink)

Highlighting main issues and controversies, this book brings together current philosophical discussions of symmetry in physics to provide an introduction to the subject for physicists and philosophers. The contributors cover all the fundamental symmetries of modern physics, such as CPT and permutation symmetry, as well as discussing symmetry-breaking and general interpretational issues. Classic texts are followed by new review articles and shorter commentaries for each topic. Suitable for courses on the foundations of physics, philosophy of physics and philosophy of science, (...) the volume is a valuable reference for students and researchers. (shrink)

Symmetry, intended as invariance with respect to a transformation (more precisely, with respect to a transformation group), has acquired more and more importance in modern physics. This Chapter explores in 8 Sections the meaning, application and interpretation of symmetry in classical physics. This is done both in general, and with attention to specific topics. The general topics include illustration of the distinctions between symmetries of objects and of laws, and between symmetry principles and symmetry arguments (such as Curie's principle), and (...) reviewing the meaning and various types of symmetry that may be found in classical physics, along with different interpretative strategies that may be adopted. Specific topics discussed include the historical path by which group theory entered classical physics, transformation theory in classical mechanics, the relativity principle in Einstein's Special Theory of Relativity, general covariance in his General Theory of Relativity, and Noether's theorems. In bringing these diverse materials together in a single Chapter, we display the pervasive and powerful influence of symmetry in classical physics, and offer a possible framework for the further philosophical investigation of this topic. (shrink)

In recent years, a ''change in attitude'' in particle physics has led to our understanding current quantum field theories as effective field theories (EFTs). The present paper is concerned with the significance of this EFT approach, especially from the viewpoint of the debate on reductionism in science. In particular, I shall show how EFTs provide a new and interesting case study in current philosophical discussion on reduction, emergence, and inter-level relationships in general.

Bewildering features of modern physics, such as relativistic space-time structure and the peculiarities of so-called quantum statistics, challenge traditional ways of conceiving of objects in space and time. Interpreting Bodies brings together essays by leading philosophers and scientists to provide a unique overview of the implications of such physical theories for questions about the nature of objects. The collection combines classic articles by Max Born, Werner Heisenberg, Hans Reichenbach, and Erwin Schrodinger with recent contributions, including several papers that have never (...) before been published. -/- The book focuses on the microphysical objects that are at the heart of quantum physics and addresses issues central to both the "foundational" and the philosophical debates about objects. Contributors explore three subjects in particular: how to identify a physical object as an individual, the notion of invariance with respect to determining what objects are or could be, and how to relate objective and measurable properties to a physical entity. The papers cover traditional philosophical topics, common-sense questions, and technical matters in a consistently clear and rigorous fashion, illuminating some of the most perplexing problems in modern physics and the philosophy of science. (shrink)

A draft version of Chapter 11 of the edited volume 'Interpreting Bodies. Classical and Quantum Objects in Modern Physics',. The Chapter is devoted to illustrating the group-theoretic approach to the issue of physical objects. In particular, the Chapter discusses the group-theoretic constitution of classical and quantum particles in the nonrelativistic case.

In recent years, a change in attitude in particle physics has led to our understanding current quantum field theories as effective field theories. The present paper is concerned with the significance of this EFT approach, especially from the viewpoint of the debate on reductionism in science. In particular, it is a purpose of this paper to clarify how EFTs may provide an interesting case-study in current philosophical discussion on reduction, emergence and inter-level relationships in general.

This is the review paper for the section III ("Symmetry breaking") of the volume "Symmetries in physics: philosophical reflections", Cambridge University Press, 2003, edited by Katherine A. Brading and Elena Castellani. The paper's sections are: 1. Preliminaries (I); 2. Symmetry breaking and Curie's analysis; 3. Preliminaries (II); 4. Symmetry breaking of physical laws (4.1. Explicit symmetry breaking; 4.2. Spontaneous symmetry breaking); 5. Symmetry breaking and philosophical questions.

Weak/strong duality is usually accompanied by what seems a puzzling ontological feature: the fact that under this kind of duality what is viewed as 'elementary' in one description gets mapped to what is viewed as 'composite' in the dual description. This paper investigates the meaning of this apparent 'particle democracy', as it has been called, by adopting an historical approach. The aim is to clarify the nature of the correspondence between 'dual particles' in the light of an historical analysis of (...) the developments of the idea of weak/strong duality, starting with Dirac's electric-magnetic duality and its successive generalizations in the context of field theory, to arrive at its first extension to string theory. This analysis is then used as evidential basis for discussing the 'elementary/composite' divide and, after taking another historical detour by analysing an instructive analogy case, drawing some conclusions on the particle-democracy issue. (shrink)

This is the first of two papers concerned with the philosophical significance of dualities as applied in recent fundamental physics. The general idea is that, for its peculiarity, this ‘new’ ingredient in theory construction can open unexpected perspectives in the current philosophical reflection on contemporary physics. In particular, today’s physical dualities represent an unusual type of intertheory relation, the meaning of which deserves to be investigated. The aim is to show how discussing this point brings into play, at the same (...) time, what is intended by a 'theory’ and in which sense dualities are to be considered 'symmetries'. This paper is introductory and focusses on the first form of duality explicitly applied in twentieth century physics, that is electromagnetic duality as discussed in Dirac’s theory of magnetic poles. The extension of electromagnetic duality in the context of quantum field theory and string theory is explored in a forthcoming companion paper. (shrink)

Is there more that one "Curie's principle"? How far are different formulations legitimate? What are the aspects that make it so scientifically fruitful, independently of how it is formulated? The paper is devoted to exploring these questions. We start with illustrating Curie's original 1894 article and his focus. Then, we consider the way that the discussion of the principle took shape from early commentators to its modern form. We say why we think that the modern focus on the inter-state version (...) of the principle loses sight of some of the most interesting significant applications of the principle. Finally, we address criticism of the principle put forward by Norton and purported counterexamples due to Roberts. (shrink)

The relevance of symmetry to today's physics is a widely acknowledged fact. A significant part of recent physical inquiry – especially the physics concerned with investigating the fundamentalbuilding blocks of nature – is grounded on symmetry principles andtheir many and far-reaching consequences. But where these symmetries come from and what their real meaning is are open questions, at the center of a developing debate among physicists and philosophers of science. To tackle the problems arising in considering the symmetry issue is (...) the main purpose of this paper. Starting with briefly recalling the bases for the discussion – how symmetry enters and operates in physics, its special effectiveness in the quantum domain and the many relevant functions it performs (Sections 1–3), the paper then focus on the general interpretative questions that arise and the sorts of answers that have been given (Section 4). (shrink)

This paper combines Alfred Shultz and Herbert Simon's theories of action in order to understand the grey area between dynamic and completely unstructured decision making better. As a result I have put together a specific scheme of how choice elements are represented from an agent's personal experience, so as to create a bridge between the phenomenological and cognitive-procedural approaches of decision making. I first look at the key points of their original models relating Alfred Schutz's “provinces of meaning” and Herbert (...) Simon's “satisficing” mechanism. I then consider the particular concept of intentionality and reasoning by analogy for different choice settings. Finally I have suggested a perspective based on creative behaviour and sense-making for ill-structured conditions. (shrink)

We argue that dualities offer new possibilities for relating fundamentality, levels, and emergence. Namely, dualities often relate two theories whose hierarchies of levels are inverted relative to each other, and so allow for new fundamentality relations, as well as for epistemic emergence. We find that the direction of emergence typically found in these cases is opposite to the direction of emergence followed in the standard accounts. Namely, the standard emergence direction is that of decreasing fundamentality: there is emergence of less (...) fundamental, high-level entities, out of more fundamental, low-level entities. But in cases of duality, a more fundamental entity can emerge out of a less fundamental one. This possibility can be traced back to the existence of different classical limits in quantum field theories and string theories. (shrink)

This paper is concerned with the problem of the validity of Leibniz's principle of the identity of indiscernibles in physics. After briefly surveying how the question is currently discussed in recent literature and which is the actual meaning of the principle for what concerns physics, we address the question of the physical validity of Leibniz's principle in terms of the existence of a sufficient number of naming predicates in the formal language of physics. This approach allows us to obtain in (...) a formal way the result that a principle of the identity of indiscernibles can be justified in the domain of classical physics, while this is not the case in the domain of quantum physics. (shrink)

This paper addresses the question as to whether the methodology followed in building/assessing string theory can be considered scientific in the same sense, say, that the methodology followed in building/assessing the Standard Model of particle physics is scientific, by focussing on the "founding" period of the theory. More precisely, its aim is to argue for a positive answer to the above question – there is no real change of scientific status in the way of proceeding and reasoning in fundamental physical (...) research – in the light of a historical analysis of the early developments of the string theoretical framework. (shrink)

Symmetry considerations dominate modern fundamental physics, both in quantum theory and in relativity. Philosophers are now beginning to devote increasing attention to such issues as the significance of gauge symmetry, quantum particle identity in the light of permutation symmetry, how to make sense of parity violation, the role of symmetry breaking, the empirical status of symmetry principles, and so forth. These issues relate directly to traditional problems in the philosophy of science, including the status of the laws of nature, the (...) relationships between mathematics, physical theory, and the world, and the extent to which mathematics suggests new physics.This entry begins with a brief description of the historical roots and emergence of the concept of symmetry that is at work in modern science. It then turns to the application of this concept to physics, distinguishing between two different uses of symmetry: symmetry principles versus symmetry arguments. It mentions the different varieties of physical symmetries, outlining the ways in which they were introduced into physics. Then, stepping back from the details of the various symmetries, it makes some remarks of a general nature concerning the status and significance of symmetries in physics. (shrink)

The aim of this paper is to investigate the consequences of the bibliometrics-based evaluation system of scientific production on the contents and methods of sciences. The research has been conducted by means of in-depth interviews to a multi-disciplinary panel of Italian researchers. We discuss the implications of bibliometrics-based evaluation on the choice of the research topic, on the experimental practices, on the dissemination habits. We observe that the validation of the bibliometrics-based evaluation practices relies on the acceptance and diffusion within (...) the scientific community, and that these practices are self-sustained through their wide application. We discuss possible evolving scenarios, also considering the recent development of digital archives. (shrink)

Bewildering features of modern physics, such as relativistic space-time structure and the peculiarities of so-called quantum statistics, challenge traditional ways of conceiving of objects in space and time. Interpreting Bodies brings together essays by leading philosophers and scientists to provide a unique overview of the implications of such physical theories for questions about the nature of objects. The collection combines classic articles by Max Born, Werner Heisenberg, Hans Reichenbach, and Erwin Schrodinger with recent contributions, including several papers that have never (...) before been published.The book focuses on the microphysical objects that are at the heart of quantum physics and addresses issues central to both the "foundational" and the philosophical debates about objects. Contributors explore three subjects in particular: how to identify a physical object as an individual, the notion of invariance with respect to determining what objects are or could be, and how to relate objective and measurable properties to a physical entity. The papers cover traditional philosophical topics, common-sense questions, and technical matters in a consistently clear and rigorous fashion, illuminating some of the most perplexing problems in modern physics and the philosophy of science.The contributors are Diederik Aerts, Max Born, Elena Castellani, Maria Luisa Dalla Chiara, Bas C. van Fraassen, Steven French, Gian Carlo Ghirardi, Roberto Giuntini, Werner Heisenberg, Decio Krause, David Lewis, Tim Maudlin, Peter Mittelstaedt, Giulio Peruzzi, Hans Reichenbach, Erwin Schrodinger, Paul Teller, and Giuliano Toraldo di Francia. (shrink)

This paper is devoted to examining the relevance of Dirac's view on the use of transformation theory and invariants in modern physics --- as it emerges from his 1930 book on quantum mechanics as well as from his later work on singular theories and constraints --- to current reflections on the meaning of physical symmetries, especially gauge symmetries.

This hefty volume amounts to a chronological encyclopedia on the history and culture of a region that draws its other name “Anatolia” from a European perspective, “Land of the Sunrise.” It ranges f...

This is a multi-authored review of a book that is extremely rich and lengthy (43 chapters, among whose titles are: Chapter III, In the name of the Lord God, this round Earth of the Ancients becomes flat again. Or perhaps not? (In which - by way of preface - the story is told of how our great Sphere, which was measured and drawn by Egyptian Alexandria, became a Mystery, Sacrilege and dark until ten years ago); Chapter X, Strabo: ‘The Pillars? (...) Gibraltar or Cádiz! But none of us have ever really seen them’ (An impossible Interview with the great Greek historian/geographer who summarizes for us what was known by the great men who preceded him. Christ had not yet been born and the site of those famous pillars had already been lost); Chapter XII, With Herodotus in the Eldorado of silver. A voyage to Tartessos, the Andalusian Atlantis (In which it will be seen that neither the Bible nor Herodotus ever said Tartessos was Spain. But only that it was in the West and beyond the Pillars of Hercules: exactly like Sardinia...); Chapter XXVIII, The Peoples-of-the-Sea versus Ramses III or the Very First World War). The author writes on culture for the daily newspaper La Repubblica. (shrink)

G.E. Moore, more than either Bertrand Russell or Ludwig Wittgenstein, was chiefly responsible for the rise of the analytic method in twentieth-century philosophy. This selection of his writings shows Moore at his very best. The classic essays are crucial to major philosophical debates that still resonate today. Amongst those included are: * A Defense of Common Sense * Certainty * Sense-Data * External and Internal Relations * Hume's Theory Explained * Is Existence a Predicate? * Proof of an External World (...) In addition, this collection also contains the key early papers in which Moore signals his break with idealism, and three important previously unpublished papers from his later work which illustrate his relationship with Wittgenstein. (shrink)

This is a draft of the introduction to the collective volume "The birth of string theory", including the book's index and preface. The book explores the history of the theory’s early stages of development, as told by its main protagonists. It journeys from the first version of the theory in the late 1960s, as an attempt to describe the physics of strong interactions outside the framework of quantum field theory, to its reinterpretation around the mid-1970s as a quantum theory of (...) gravity unified with the other interactions, and its successive developments up to the superstring revolution in 1984. The introductive Chapter summarizes the main developments and contains a chronological synopsis with a list of key results and publications. (shrink)