Faculty of Arts and Philosophy Centre for Logic and Philosophy of Science Director: Prof. Dr. E. Weber Theory Choice in Physics by Peter Rubbens Promotor: Dr. R. De Langhe Dissertation submitted to obtain the grade of Postgraduate in Logic, History and Philosophy of Science Academic Year 2014{2015 Toelating tot bruikleen \De auteur geeft de toelating deze scriptie voor consultatie beschikbaar te stellen en delen van de scriptie te kopi¨erenvoor persoonlijk gebruik. Elk ander gebruik valt onder de beperkingen van het auteursrecht, in het bijzonder met betrekking tot de verplichting de bron uitdrukkelijk te vermelden bij het aanhalen van resultaten uit deze scriptie." \The author gives the permission to use this thesis for consultation and to copy parts of it for personal use. Every other use is subject to the copyright laws, more specifically the source must be extensively specified when using from this thesis." Peter Rubbens, January 2015 i Contents Toelating tot bruikleeni Table of Contents ii 1 Introduction1 2 From Theory Choice to Theory Search: The Essential Tension between Exploration and Exploitation in Science5 3 Evaluation of the OPERA Collaboration and the Faster than Light Neu- trino Anomaly 16 4 Conclusion 32 Bibliography 36 ii Chapter 1 Introduction This thesis contains the final product of two papers written during the \Postgraduate Stud- ies in the Logic, History and Philosophy of Science". In this chapter I will first introduce these two papers separately, after which I will outline their relevance concerning their respective fields, to end with a note on what both papers can mean for each other. The first paper is titled \From Theory Choice to Theory Search: The Essential Tension between Exploration and Exploitation in Science" (FTCTS) and has been written in collab- oration with dr. Rogier De Langhe [7]. It will appear in a special issue concerning Thomas Kuhn of the edited volume \Boston Studies in the Philosophy and History of Science". FTCTS is part of the research that tries to model scientific revolutions by means of agent- based-modeling. It uses the complex-systems-approach, in which it perceives a scientific community along with its dynamics as a complex system. As Newman notes, there is no technical and precise definition of a complex system, but the definition he uses is quite apt: \a system composed out of many interacting parts, such that the collective behaviour of those parts together is more than the sum of their individual behaviours" [16, p. 1]. The collective behaviour is dubbed emergent behaviour. FTCTS proposes a model which shows that it is possible for scientists, who solely interact on a local level, to undergo a scientific revolution at the collective level, the entire scientific community. The mechanism behind this phenomenon is the balance scientists try to find between exploitation and exploration of a theory or paradigm. The few scientists who try to explore alternative theories instead of exploiting the existing ones are the ones who pave the way for other scientists to follow in a later stage. In this way theory choice becomes an activity of theory search; a minority of scientists explore theories until they find a theory 1 2 which fit their merits better. When this point is reached, the entire scientific community switches to this alternative theory. As this switch is quite sudden and consists out of quasi the entire scientific community, we are allowed to dub this non-cumulative break as a scientific revolution. The model is remarkably robust. The first research considering the modelling of scientific revolutions originates in the work of John D. Sterman in 1985 [20]. In this paper Sterman attempts to test the dynamic con- sistency of Kuhn's theory by formalizing it and subsequently simulating it on the computer. The main variable in the model of Sterman is a scientist's confidence in a paradigm (CP ). CP = 1 represents total commitment, CP = 0 total rejection. CP is determined by the relative number of accumulated anomalies (RA) and the rate of progress of the paradigm (RSP ). Based on CP , scientists adhere or leave paradigms. With this model, Sterman is able to let a majority of a virtual scientific community adhere a certain paradigm for a significant amount of time, after which the number of adherents suddenly declines and another paradigm emerges. The lifetime of such a `dominant' paradigm varies. This research gained new insights after Wittenberg uttered some critiques to Sterman's research in 1992 [25]. Wittenberg argues that Sterman exceeds \a modeler's prerogative of reinterpretation". Furthermore he is of the opinion that there are a number of method- ological problems when trying to model Kuhnian science. However, Sterman states in the same edition of \System Dynamics Review" that he disagrees with Wittenberg [21].1 Hereafter Sterman and Wittenberg joined forces, which results in a new version of the model in 1999 [22]. New theories are now stochastically and endogenously created and by means of positive feedback loops can unobservable microlevel perturbations become important; this makes the dynamics path-dependent and a self-organizing evolutionary system, typical features of complex systems. Recently, there has been an attempt by Bornholdt et al. where the emergence and de- cline of paradigms is modelled by means of agent-based modelling [4]. Agents, in this case scientists, are able to adhere a certain paradigm, but a memory requirement makes sure a scientist cannot go back to a previous paradigm. By means of cooperative effects, paradigms who have more adherents will attract more scientists. However, there is an 1Other responses in \System Dynamics Review" to the original model of Sterman are the one by Yaman Barlas who states that it is not fundamentally but practically impossible to model Kuhnian revolutions [3], and Michael J. Radzicki who suggests to introduce noise rather than aggregation in order to represent the idiosyncrasies of scientists [18]. 3 exogenous parameter α which introduces new paradigms to which scientists are also able to switch to. This model results in a regular pattern of global paradigm shifts.2 FTCTS differs from previous researches in the following sense: all predescribed models use a global parameter to guide a scientific community to a new theory where FTCTS does not, FTCTS is based on pure local interactions. Moreover, it encompasses a majority of characteristics which previous models also displayed: FTCTS gives rise to non-cumulative breaks in a self-organising and endogenous way. Chapter3 consists of a paper originally developed for the course “Scientific Explanation" and is titled \Evaluation of the OPERA Collaboration and the Faster than Light Neutrino Anomaly" (EVAL) [19]. It is displayed in the format as it has been submitted to the journal \Synthese".3 In November 2011 the OPERA collaboration released results which seemed to originate from neutrinos which are able to travel faster than the speed of light c. It took almost a year, until July 2012, before it was clear the results were erroneous due to defects in the experimental set-up. This paper is an attempt to evaluate the scientific practice of the OPERA collaboration. The first part of EVAL consists out of a schematic overview of the communication by the OPERA collaboration combined with a sketch of the complexity of the experiment. It ends with a brief explanation of how the OPERA collaboration got to their erroneous measurements. The second part of EVAL tries to evaluate the scientific practice of the OPERA collabo- ration. In order to do this properly, the toolbox developed by Weber, Van Bouwel and De Vreese is used [24, section 3.7]. This toolbox evaluates a scientific practice on five different levels: explanation-seeking questions and epistemic interests, the appropriate format of an explanation, explanation and levels of rationality, abstraction and amount of details in explanation and irrelevant premises. Originally it might seem there is not much overlap between the two papers. However, the OPERA episode might be a suitable case-study of scientists choosing between the roles 2However, it can be shown that the memory requirement is unrealistic and on top of that not even necessary to achieve this behaviour [13]. 3Synthese rejected the paper on the basis that they find the philosophical basis too thin. I will now try to submit it to \Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics". In the meanwhile a preprint is published on the \PhilSci-Archive". 4 of on the one hand explorers and on the other exploiters. During the OPERA episode the majority of the physics community kept up a skeptical stance towards the OPERA results and kept exploiting the paradigm in which they were working in. Only a few scientists started exploring other possible paths, of which the most important one is that of superluminality. Superluminality considers phenomena which appear to travel faster than the speed of light. Giovanni Amelino-Camelia points out that their already existed earlier work on superluminality [1]. This work emerged from research performed on quantum- gravity. Some studies argue that there will be a departure from Einstein his theory of relativity ath the Planck-length. Superluminality is a possibility in these cases. Because of the initial results of OPERA, research was stimulated to focus on superluminal neutrinos. Considering superluminal neutrinos are possible, further research had to be undertaken to on the one hand confirm superluminal neutrinos are actually possible and on the other find the limits within which superluminal neutrinos are possible to measure. For example, Gian Giudice, Sergey Sibiryakov, and Alessandro Strumia proved that super- luminal neutrinos would result in anomalies for the velocities of electrons and muons [8]. By means of cosmic ray data such anomalies could already be ruled out, which contradicts the OPERA results.