Koray Karaca

I examine the relation between explanation and unification in both the original Kaluza–Klein theory, which originated in the works of Theodor Kaluza and Oskar Klein in the 1920s, and in the modern Kaluza–Klein theories which date back to the late 1970s and which are still considered by the majority of the physics community to be the best hope for a complete unified theory of all fundamental interactions. I use the conclusions of this case study to assess the merits of Philip Kitcher's account of explanation as unification. I also draw lessons about physicists’ pursuit of the higher dimensional unification of the fundamental forces of nature

We examine physicists’ charge of ad hocness against the Higgs mechanism in the standard model of elementary particle physics. We argue that even though this charge never rested on a clear-cut and well-entrenched definition of “ad hoc”, it is based on conceptual and methodological assumptions and principles that are well-founded elements of the scientific practice of high-energy particle physics. We further evaluate the implications of the recent discovery of a Higgs-like particle at the CERN’s Large Hadron Collider for the charge of ad hocness against the Higgs mechanism

ArgumentIn the theory-dominated view of scientific experimentation, all relations of theory and experiment are taken on a par; namely, that experiments are performed solely to ascertain the conclusions of scientific theories. As a result, different aspects of experimentation and of the relations of theory to experiment remain undifferentiated. This in turn fosters a notion of theory-ladenness of experimentation (TLE) that is toocoarse-grainedto accurately describe the relations of theory and experiment in scientific practice. By contrast, in this article, I suggest that TLE should be understood as anumbrella conceptthat has different senses. To this end, I introduce a three-fold distinction among the theories of high-energy particle physics (HEP) as background theories, model theories, and phenomenological models. Drawing on this categorization, I contrast two types of experimentation, namely, “theory-driven” and “exploratory” experiments, and I distinguish between the “weak” and “strong” senses of TLE in the context of scattering experiments from the history of HEP. This distinction enables identifying the exploratory character of the deep-inelastic electron-proton scattering experiments – performed at the Stanford Linear Accelerator Center (SLAC) between the years 1967 and 1973 – thereby shedding light on a crucial phase of the history of HEP, namely, the discovery of “scaling,” which was the decisive step towards the construction of quantum chromo-dynamics as a gauge theory of strong interactions.

I examine the construction process of the “Higgs mechanism” and its subsequent use by Steven Weinberg to formulate the electroweak theory of elementary particle physics. I characterize the development of the Higgs mechanism as a historical process that was guided through analogies drawn to the theories of solid-state physics and that was progressive through diverse contributions in the sixties from a number of physicists working independently. I also offer a detailed comparative study of the similarities and the differences that exist between the approaches taken in these contributions

In this paper, I address the issue of to what extent the theory-dominated view of scientific experimentation describes scientific practice. I rely on a time period from the history of High Energy Physics (HEP), which spans from early 1960s to early 1970s. I argue that theory-ladenness of experimentation (TLE), which grounds theory-dominated conception of experimentation is too coarse-grained inasmuch as it prevents us from seeing the correct relationship that exists between theorizing and experimenting in the scientific practice of HEP. I articulate that in order to be able to get a better understanding of scientific practice, a revision needs to be made in the general conception of TLE. I propose that such a revision is possible if we abandon the commitment that experimentation is always driven by theory. I consider what I call “theory-drivenness” of experimentation (TDE) as a form of theory-ladenness, which amounts to the claim that experiments, from their initial design up to their final stage, are carried out under the framework of a prevailing theory for the purpose of providing definite answers to specific questions already posed by the same theory. I argue that electron-proton inelastic scattering experiments in HEP were firstly carried out without having any recourse to a phenomenological model. From here, I claim that these experiments are not theory-laden in the sense implied by TDE. On the other hand, I argue, inelastic scattering experiments are theory-laden due to the fact that the scientists who perform them are committed to background theories of HEP. That is, I admit the validity of TLE as a philosophical claim, but I attribute a weaker status to it as opposed to its general conception. That is, I propose to differentiate TDE from TLE by claiming that TLE does not entail TDE.

In this paper, I propose an account that accommodates the possibility of experimentation being exploratory in cases where the procedures necessary to plan and perform an experiment are dependent on the theoretical accounts of the phenomena under investigation. The present account suggests that experimental exploration requires the implementation of an exploratory procedure that serves to extend the range of possible outcomes of an experiment, thereby enabling it to pursue its objectives. Furthermore, I argue that the present account subsumes the notion of exploratory experimentation, which is often attributed in the relevant literature to the works of Friedrich Steinle and Richard Burian, as a particular type of experimental exploration carried out in the special cases where no well-formed theoretical framework of the phenomena under investigation exists. I illustrate the present account in the context of the ATLAS experiment at CERN’s Large Hadron Collider, where the long-sought Higgs boson has been discovered in 2012. I argue that the data selection procedure carried out in the ATLAS experiment illustrates an exploratory procedure in the sense suggested by the present account. I point out that this particular data selection procedure is theory-laden in that its implementation is crucially dependent on the theoretical models of high energy particle physics which the ATLAS experiment is aimed to test. However, I argue that the foregoing procedure is not driven by the above-mentioned theoretical models, but rather by a particular data selection strategy. I conclude that the ATLAS experiment illustrates that, contrary to what previous studies have suggested, there are cases of experimentation in which exploration serves to test theoretical predictions and that theory-ladenness plays an essential role in experimentation being exploratory.

The present special section brings together three articles that seek to elucidate the epistemological and ontological foundations of the Higgs mechanism, as well as the epistemic dynamics of the development of the models beyond the “standard model” of elementary particle physics.The standard model of elementary particle physics consists of two gauge theories; namely, the electroweak theory of the weak and electromagnetic interactions, and the theory of quantum chromo-dynamics which describes the strong interaction. This introduction will provide a brief overview of the key issues concerning the foundations of the Higgs mechanism.Historically, the main motivation for the Higgs mechanism stemmed from the need to account for the non-zero masses of the intermediate vector bosons of the weak interaction within a gauge theory of the Yang-Mills type. One way to give mass to the IVBs, called “explicit symmetry breaking,” is to add mass terms directly to the Lagrangian of the gauge theor ..

In the theory-dominated view of scientific experimentation, all relations of theory and experiment are taken on a par; namely, that experiments are performed solely to ascertain the conclusions of scientific theories. As a result, different aspects of experimentation and of the relation of theory to experiment remain undifferentiated. This in turn fosters a notion of theory-ladenness of experimentation that is too coarse-grained to accurately describe the relations of theory and experiment in scientific practice. By contrast, in this article, I suggest that TLE should be understood as an umbrella concept that has different senses. To this end, I introduce a three-fold distinction among the theories of high-energy particle physics as background theories, model theories and phenomenological models. Drawing on this categorization, I contrast two types of experimentation, namely, “theory-driven” and “exploratory” experiments, and I distinguish between the “weak” and “strong” senses of TLE in the context of scattering experiments from the history of HEP. This distinction enables to identify the exploratory character of the deep-inelastic electron-proton scattering experiments—performed at the Stanford Linear Accelerator Center between the years 1967 and 1973—thereby shedding light on a crucial phase of the history of HEP, namely, the discovery of “scaling”, which was the decisive step towards the construction of quantum chromo-dynamics as a gauge theory of strong interactions.

Gravity’s Ghost is a book about the search for gravitational waves , which are predicted by the general theory of relativity to be ripples in space–time that propagate at the speed of light. The direct detection of GWs, if they exist at all, is exceptionally difficult, because they are theoretically expected to be very weakly coupled to matter. To this date, there is yet no conclusive evidence for the direct detection of GWs. The search for GWs was started by a series of experiments performed by Joseph Weber in the 1960s. The history of the early GW detection experiments, as well as Weber’s claimed detection of GWs, which was eventually discredited, has been examined in great details by Harry Collins .Collins has long advocated a sociological approach to the study of scientific research groups that is premised on the view that in order to understand how scientific knowledge is produced collectively by a group of researchers, it is necessary to engage in the cultu ..