String theory has been the dominating research field in theoretical physics during the last decades. Despite the considerable time elapse, no new testable predictions have been derived by string theorists and it is understandable that doubts have been voiced. Some people have argued that it is time to give up since testability is wanting. But the majority has not been convinced and they continue to believe that string theory is the right way to go. This (...) situation is interesting for philosophy of science since it highlights several of our central issues. In this paper we will discuss string theory from a number of different perspectives in general methodology. We will also relate the realism/antirealism debate to the current status of string theory. Our goal is two-fold; both to take a look at string theory from philosophical perspectives and to use string theory as a test case for some philosophical issues. (shrink)

In this paper, I offer an analysis of the radical disagreement over the adequacy of string theory. The prominence of string theory despite its notorious lack of empirical support is sometimes explained as a troubling case of science gone awry, driven largely by sociological mechanisms such as groupthink (e.g. Smolin 2006). Others, such as Dawid (2013), explain the controversy by positing a methodological revolution of sorts, according to which string theorists have quietly turned to nonempirical (...) methods of theory assessment given the technological inability to directly test the theory. The appropriate response, according to Dawid, is to acknowledge this development and widen the canons of acceptable scientific methods. As I’ll argue, however, the current situation in fundamental physics does not require either of these responses. Rather, as I’ll suggest, much of the controversy stems from a failure to properly distinguish the “context of justification” from the “context of pursuit”. Both those who accuse string theorists of betraying the scientific method and those who advocate an enlarged conception of scientific methodology objectionably conflate epistemic justification with judgements of pursuit-worthiness. Once we get clear about this distinction and about the different norms governing the two contexts, the current situation in fundamental physics becomes much less puzzling. After defending this diagnosis of the controversy, I’ll show how the argument patterns that have been posited by Dawid as constituting an emergent methodological revolution in science are better off if reworked as arguments belonging to the context of pursuit. (shrink)

String theory has played a highly influential role in theoretical physics for nearly three decades and has substantially altered our view of the elementary building principles of the Universe. However, the theory remains empirically unconfirmed, and is expected to remain so for the foreseeable future. So why do string theorists have such a strong belief in their theory? This book explores this question, offering a novel insight into the nature of theory assessment itself. Dawid (...) approaches the topic from a unique position, having extensive experience in both philosophy and high-energy physics. He argues that string theory is just the most conspicuous example of a number of theories in high-energy physics where non-empirical theory assessment has an important part to play. Aimed at physicists and philosophers of science, the book does not use mathematical formalism and explains most technical terms. (shrink)

String Theory is the result of the conjunction of three conceptually independent elements: the metaphysical idea of a nomological unity of the forces, the model-theoretical paradigm of Quantum Field Theory, and the conflict resulting from classical gravity in a quantum world - the motivational starting point of the search for a theory of Quantum Gravity. String Theory is sometimes assumed to solve this conflict: by means of an application of the model-theoretical apparatus of Quantum (...) Field Theory, interpreting gravity as the result of an exchange of gravitons, taken here to be dynamical states of the string. But, String Theory does not really solve the conflict. Rather it exemplifies the inadequacy of the apparatus of Quantum Field Theory in the context of Quantum Gravity: After several decades of development it still exists only in an essentially perturbative formulation. And, due to its quantum field theoretical heritage, it is conceptually incompatible with central implications of General Relativity, especially those resulting from the general relativistic relation between gravity and spacetime. All known formulations of String Theory are background-dependent. And no physical motivation is given for this conceptual incompatibility. On the other hand, although String Theory identifies all gauge bosons as string states, it was not even possible to reproduce the Standard Model. Instead, String Theory led to a multitude of internal problems - and to the plethora of low-energy scenarios with different nomologies and symmetries, known as the String Landscape. All attempts to find a dynamically motivated selection principle remained without success, leaving String Theory without any predictive power. The nomological unification of the fundamental forces, including gravity, is only achieved in a purely formal way within the model-theoretical paradigm of Quantum Field Theory - by means of physically unmotivated epicycles like higher dimensionality, Calabi-Yau spaces, branes, etc. Finally, the possibility remains that some of the central assumptions of String Theory are physically wrong. On the one hand, the idea of a nomological unity of the forces could be simply wrong. On the other hand, even if a nomological unity of all fundamental forces should be realized in nature, the possibility remains that gravity is not a fundamental force, but a residual, emergent and possibly intrinsically classical phenomenon, resulting from a quantum substrate without any gravitational degrees of freedom. (shrink)

Eternalism, the view that what we regard locally as being located in the past, the present and the future equally exists, is the best ontological account of temporal existence in line with special and general relativity. However, special and general relativity are not fundamental theories and several research programs aim at finding a more fundamental theory of quantum gravity weaving together all we know from relativistic physics and quantum physics. Interestingly, some of these approaches assert that time is not (...) fundamental. If time is not fundamental, what does it entail for eternalism and the standard debate over existence in time? First, I will argue that the non-fundamentality of time to be found in string theory entails standard eternalism. Second, I will argue that the non-fundamentality of time to be found in loop quantum gravity entails atemporal eternalism, namely a novel position in the spirit of standard eternalism. (shrink)

During its forty year lifespan, string theory has always had the power to divide, being called both a 'theory of everything' and a 'theory of nothing'. Critics have even questioned whether it qualifies as a scientific theory at all. This book adopts an objective stance, standing back from the question of the truth or falsity of string theory and instead focusing on how it came to be and how it came to occupy its (...) present position in physics. An unexpectedly rich history is revealed, with deep connections to our most well-established physical theories. Fully self-contained and written in a lively fashion, the book will appeal to a wide variety of readers from novice to specialist. (shrink)

It is sometimes claimed that string theory posits a fundamental ontology including extended mereological simples, either in the form of minimum-sized regions of space or of the strings themselves. But there is very little in the actual theory to support this claim, and much that suggests it is false. Extant string theories treat space as a continuum, and strings do not behave like simples.

Weyl symmetry of the classical bosonic string Lagrangian is broken by quantization, with profound consequences described here. Reimposing symmetry requires that the background space-time satisfy the equations of general relativity: general relativity, hence classical space-time as we know it, arises from string theory. We investigate the logical role of Weyl symmetry in this explanation of general relativity: it is not an independent physical postulate but required in quantum string theory, so from a certain point of (...) view it plays only a formal role in the explanation. (shrink)

In this paper, some conceptual issues are addressed in order to make sense of what string theory is supposed to tell us about spacetime. The dualities in string theory are used as a starting point for our argumentation. We explore the consequences of a standard view towards these dualities, namely that the dual descriptions represent the same physical situation. Given this view, one has to understand string theory in a manner such that what counts (...) as physical spacetime is based only on the shared physical content—or common core—of the dual descriptions. In general such a spatiotemporal picture does not have to agree with, or be similar to, any of the ones suggested by naïve readings of the dual descriptions. However, in certain regimes or limits, one or the other of the initial dual descriptions may give a good effective description of physical spacetime. (shrink)

String theory promises to be able to provide us with a working theory of quantum gravity and a unified description of all fundamental forces. In string theory there are so called ‘dualities’; i.e. different theoretical formulations that are physically equivalent. In this article these dualities are investigated from a philosophical point of view. Semantic and epistemic questions relating to the problem of underdetermination of theories by data and the debate on realism concerning scientific theories are (...) discussed. Depending on ones views on semantic issues and realism different interpretations are possible of the dualities. (shrink)

String theory has by now maintained a highly influential position in high energy physics for more than a quarter of a century. The present article analyses the reasons for the considerable trust exponents of string theory have in their theory even though it has neither found empirical confirmation nor a complete formulation up to this point. It is argued that this trust can be understood in terms of an emerging new conception of theory assessment (...) that relies strongly on the identification of limitations to the underdetermination of scientific theory building. The second part of the paper makes the point that another conspicuous element of string theoretical reasoning, the prominent role of the notion of a final theory, can be understood in terms of this altered notion of theory assessment as well. (shrink)

Some philosophers of science have suggested that contemporary science should be the source of inspiration to the new analytic metaphysics (A. Chakra vartty, C. Callender, S. French, J. Ladyman, T. Maudlin, etc.). This paper explores the prospect of a string metaphysics: a research program in analytic metaphysics based on string theory. Different forms of fundamentalism and pluralism are discussed in this context. The paper focus on string metaphysics with S-dualities (a relation between models of string (...) theory at different coupling regimes) and argues that fundamentality and compositionality have to be reconceptualized. String metaphysics with dualities is better couched in terms of metaphysical pluralism. Grounding, as well as a sketch of a string modality, are briefly discussed. The paper concludes with a suggestion for future work: the metaphysician may find a productive ground for research in discussing other dualities (especially the T-dualities, or the AdS/CFT duality), the emergence of spacetime, the concept of time in string theory, the multiverse etc. (shrink)

I will give arguments for why the enormous progress made during the last century on understanding elementary particles and their fundamental interactions suggests strings as the truly elementary constituents of Nature. I will then address the issue of whether the string paradigm can in principle be falsified or whether it should be considered as mere metaphysics.

Currently, string theory represents the only advanced approach to a unification of all interactions, including gravity. In spite of the more than thirty years of its existence, the sequence of metamorphosis it ran through, and the ever more increasing number of involved physicists, until now, it did not make any empirically testable predictions. Because there are no empirical data incompatible with the quantum field theoretical standard model of elementary particle physics and with general relativity, the only motivations for (...) string theory rest in the mutual incompatibility of the standard model and of general relativity as well as in the metaphysics of the unification program of physics, aimed at a final unified theory of all interactions including gravity. But actually, it is completely unknown which physically interpretable principles could form the basis of string theory. At the moment, "string theory" is no theory at all, but rather a labyrinthic structure of mathematical procedures and intuitions which get their justification from the fact that they, at least formally, reproduce general relativity and the standard model of elementary particle physics as low energy approximations. However, there are now strong indications that string theory does not only reproduce the dynamics and symmetries of our standard model, but a plethora of different scenarios with different low energy nomologies and symmetries. String theory seems to describe not only our world, but an immense landscape of possible worlds. So far, all attempts to find a selection principle which could be motivated intratheoretically remained without success. So, recently the idea that the low energy nomology of our world, and therefore also the observable phenomenology, could be the result of an anthropic selection from a vast arena of nomologically different scenarios entered string theory. Although multiverse scenarios and anthropic selection are not only motivated by string theory, but lead also to a possible explanation for the fine tuning of the universe, they are concepts which transcend the framework defined by the epistemological and methodological rules which conventionally form the basis of physics as an empirical science. (shrink)

For each positive n , two alternative axiomatizations of the theory of strings over n alphabetic characters are presented. One class of axiomatizations derives from Tarski's system of the Wahrheitsbegriff and uses the n characters and concatenation as primitives. The other class involves using n character-prefixing operators as primitives and derives from Hermes' Semiotik. All underlying logics are second order. It is shown that, for each n, the two theories are definitionally equivalent [or synonymous in the sense of deBouvere]. (...) It is further shown that each member of one class is synonymous with each member of the other class; thus that all of the theories are definitionally equivalent with each other and with Peano arithmetic. Categoricity of Peano arithmetic then implies categoricity of each of the above theories. (shrink)

The unfolding of string theory has led to a successive refinement and generalization of our understanding of geometry and topology. A brief overview of these developments is given.

The PreambleIn the early seventies the newly discovered gauge symmetries had made it possible to give a unified description of three of the four basic forces in nature.Dawid [1]. However, it remained a mystery how the force of gravity was to be incorporated in the resulting standard model. In 1974 it was proposed by Joel Scherk and John Schwarz that string theory—which until then was regarded as a theory only of hadrons—was a theory that could unite (...) the whole of microphysics. The promise of full unification attracted many researchers to the field of string theory. A lot of work was done which expanded the mathematical framework and in 1984 Scherk and Schwarz finally succeeded in formulating the Lagrangian of the superstring: a quantised string that includes a matter field. With the mathematical formalism now firmly in place, the scientific community waited for experimental verification of the string hypothesis. And it waited.The Current DebateToday, more than 40 years after the earlies. (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.

After reviewing the original motivation for the formulation of string theory and what we learned from it, I discuss some of the implications of the holographic principle and of string dualities for the question of the building blocks of nature.

Evolution in Four Dimensions claims that epigenetic, behavioral, and symbolic inheritance systems should be considered equal partners to genetics in evolutionary biology. The evidence for, and applicable scope of, these additional inheritance systems is limited, particularly with regard to areas involving learning. It is unclear how including these extra dimensions in mainstream evolutionary thinking translates into testable hypotheses for a productive research program.

In this paper I first describe some simple, but interesting string theory. Then I discuss string field theory and suggest that even though we do not have a complete mathematical formulation, we can get an idea of some of its ontological implications. Next, the significance of supersymmetry and superspace in string theory is briefly considered. Lastly, I consider the question of whether there is, in fact, (good) reason to think string theory may (...) (or will) emerge to replace quantum field theory. (shrink)

We will investigate the implications of string theory for the scientific realism debate. Duality relations, which constitute a crucial conceptual characteristic of string theory, are of particular importance for the question of scientific realism in two ways. First, string dualities relate seemingly very different realizations of string theory to each other and establish their empirical equivalence. This feature of string theory works against an ontologically realist interpretation of the theory by (...) turning pivotal characteristics of ontological objects into a matter of choosing a specific formulation of the theory. Second, string dualities provide a basis for a final theory claim with respect to string theory. This final theory claim can provide a new conceptual framework for a realist interpretation of the theory. The final part of the talk will sketch the basic outlines of a realist conception that seems adequate in a string theoretical context. (shrink)

String theory currently is the only viable candidate for a unified description of all known natural forces. This article tries to demonstrate that the fundamental structural and methodological differences that set string theory apart from other physical theories have important philosophical consequences. Focussing on implications for the realism debate in philosophy of science, it is argued that both poles of that debate face new problems in the context of string theory. On the one hand, (...) the claim of underdetermination of scientific theory by the available empirical data, which is a pivotal element of empiricism, loses much of its plausibility. On the other hand, the dissolution of any meaningful notion of an external ontological object destroys the basis for conventional versions of scientific realism. String theory seems to suggest an intermediate position akin to Structural Realism that is based on a newly emerging principle, to be called the principle of theoretical uniqueness. (shrink)

String theory is at the moment the only advanced approach to a unification of all interactions, including gravity. But, in spite of the more than 30 years of its existence, it does not make any empirically testable predictions, and it is completely unknown which physically interpretable principles could form the basis of string theory. At the moment, “string theory” is no theory at all, but rather a labyrinthic structure of mathematical procedures and intuitions. (...) The only motivations for string theory consist in the mutual incompatibility of the standard model of quantum field theory and of general relativity as well as in the metaphysics of the unification program of physics, aimed at a final unified theory of all interactions, including gravity. The article gives a perspective on the problems leading to and resulting from this situation. (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)

. Over the last three decades, physicists have engaged in, sometimes heated, debates about relative merits and prospects of string theory as a viable research program and even about its status as a science. The aim of this paper is to provide a deeper understanding of this controversy as a particular form of boundary discourse. Drawing on the sociological work of Thomas Gieryn and Lawrence Prelli, we bring to light the way in which protagonists appeal to, and rhetorically (...) construct, different views about the scientific method and the scientific ethos, in an effort to legitimize or delegitimize string theory. (shrink)

The current status of string theory is assessed quite differently by most of the theory’s exponents than by the majority of physicists in other fields. While the former tend to have a high degree of trust in string theory’s viability, the latter largely share a substantially more skeptical point of view. This article argues that the controversy can be best understood in terms of a paradigmatic rift between the two sides over their understandings of (...) class='Hi'>theory assessment. An attempt is made to evaluate the two conflicting paradigms on their own terms. †To contact the author, please write to: Institute Vienna Circle, University of Vienna, Universtitätscampus Spitalgasse 2‐4, Hof 1, 1090 Vienna, Austria; e‐mail: [email protected]. (shrink)

The modeling of black holes is an important desideratum for any quantum theory of gravity. Not only is a classical black hole metric sought, but also agreement with the laws of black hole thermodynamics. In this paper, we describe how these goals are achieved in string theory. We review black hole thermodynamics, and then explicate the general stringy derivation of classical spacetimes, the construction of a simple black hole solution, and the derivation of its entropy. With that (...) in hand, we address some important philosophical and conceptual questions: the confirmatory value of the derivation, the bearing of the model on recent discussions of the so-called ‘information paradox’, and the implications of the model for the nature of space. (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)

We identify new, rather serious, physical and mathematical inconsistencies of the current formulation of noncanonical or nonunitary string theories due to the lack of invariant units necessary for consistent measurements, lack of preservation in time of Hermiticity-observability, and other shortcomings. We propose three novel reformulations of string theories for matter of progressively increasing complexity via the novel iso-, geno-, and hyper-mathematics of hadronic mechanics, which resolve the current inconsistencies, while offering new intriguing possibilities, such as: an axiomatically consistent (...) and invariant inclusion of gravity, the reduction of macroscopic irreversibility to the most primitive level of vibrations of the universal substratum (ether), or the treatment of multi-valued, irreducible, biological structures. We then identify three corresponding classical formulations of string theories for antimatter via the novel anti-isomorphic isodual mathematics. We finally outline the intriguing features of the emerging new cosmologies (including biological structures, as it should be for all cosmologies), such as: universal invariance (rather than covariance) under a symmetry isomorphic to the Poincaré group and its isodual; equal distributions of matter and antimatter in the universe (as a limit case); continuous creation; no need for the missing mass; significantly reduced dimensions; possibility of experimental identification of antimatter in the universe; identically null total characteristics of time, energy, linear and angular momentum, charge, etc.; and other intriguing features. (shrink)

String theory is often depicted as the best chance for natural science to find a Theory of Everything. Whiteheadians may object that only a philosophical cosmology such as Whitehead presents in PR can “frame a coherent, logical, necessary system of general ideas in terms of which every element of our experience can be interpreted” (PR 3). But then they have to show that Whitehead’s scheme and string theory fit together nicely, with each helping to resolve (...) residual problem areas in the other. The present article conjectures that the tiny vibrating strings postulated by string theory and the superjects of individual actual entities might correspond to the “final, real things of which the world is made up” (PR 18). Likewise, the extra spatial dimensions required by the mathematics of string theory might be more intelligible in terms of the interaction of different levels of subsocieties within a Whiteheadian structured society. (shrink)

String theory reduces to general relativity in appropriate regimes. Huggett and Vistarini have given an account of this reduction that includes a deflationary thesis about symmetry: although the usual derivation of general relativity from string theory appeals to a premise about the theory’s symmetry, Huggett and Vistarini argue that this premise plays no logical role. In this article I disagree with their deflationary thesis and argue that their analysis is based on a popular but flawed (...) conception of the interaction between symmetry and quantization. I argue that a better conception recognizes a distinction between ordinary, broken, and anomalous symmetries. (shrink)

This article investigates the implications of string theory for the conception of scientific theory confirmation. The classical understanding of theory confirmation is based on the assumption that scientific theory building is underdetermined by the available empirical data. Several arguments are presented, which suggest a devaluation of this ‘principle of scientific underdetermination’ in the context of string theory. An altered conception of scientific progress emerges that is not based on the notion of theory (...) succession. (shrink)

The nature of space and time is one of the most fascinating and fundamental areas of the philosophy of physics. This study aims to provide a complete account of current debates in the application of spacetime to string theory. String theory has been an important discipline within physics for many years but is only now being applied to the problems faced by philosophers of science. This emerging area of physics is discussed in relation to a number (...) of theories including general relativity, T-duality and moduli space, and set in the context of current and future research. (shrink)

SAINT JOAN OF NEW YORK is a novel about a math prodigy who becomes obsessed with discovering the Theory of Everything. Joan Cooper, a 17-year-old genius traumatized by the death of her older sister, tries to rebuild her shattered world by studying string theory and the efforts to unify the laws of physics. But as she tackles the complex equations, she falls prey to disturbing visions of a divine being who wants to help her unveil the universe’s (...) mathematical design. Joan must enter the battle between science and religion, fighting for her sanity and a new understanding of the cosmos. (shrink)

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)

Anthropic reasoning has lately been strongly associated with the string theory landscape and some theories of particle cosmology, such as cosmological inflation. The association is not, contrary to multiple statements by physicists and philosophers alike, necessary. On the contrary, there are clear reasons and instances in which the anthropic reasoning is useful in a diverse range of fields such as planetary sciences, geophysics, future studies, risk analysis, origin of life studies, evolutionary theory, astrobiology and SETI studies, ecology, (...) or even strategic studies and global policy. The association of anthropic reasoning with string theory and particle cosmology has not only become the standard wisdom, but has been often construed in a negative way, in order to demonstrate or insinuate that such reasoning is too abstract or even belongs to 'fringe science', remote from run-of-the-mill research practices in any other more 'mundane' and less theoretical scientific discipline. The purpose of this paper is to (i) analyse some of the counter-examples to the standard wisdom, (ii) suggest that the anthropic reasoning is more flexible, more general, and less fashion-driven than the detractors state. In addition, we consider some historical and/or extrascientific motivation for this persistent prejudice. (shrink)