Reason and Representation in Scientific Simulation Matthew Spencer | PhD Thesis Centre for Cultural Studies, Goldsmiths, University of London Declaration The work presented in this thesis is the candidate's own. - 2 - Abstract This thesis is a study of scientific practice in computational physics. It is based on an 18 month period of ethnographic research at the Imperial College Applied Modelling and Computation Group. Using a theoretical framework drawn from practice theory, science studies, and historical epistemology, I study how simulations are developed and used in science. Emphasising modelling as a process, I explore how software provides a distinctive kind of material for doing science on computers and how images and writings of various kinds are folded into the research process. Through concrete examples the thesis charts how projects are devised and evolve and how they draw together materials and technologies into semi-stable configurations that crystallise around the objects of their concern, what Hans-Jorg Rheinberger dubbed “epistemic things”. The main pivot of the research, however, is the connection of practice-theoretical science studies with the philosophy of Gaston Bachelard, whose concept of “phenomenotechnique” facilitates a rationalist reading of scientific practice. Rather than treating reason as a singular logic or method, or as a faculty of the mind, Bachelard points us towards processes of change within actual scientific research, a dynamic reason immanent to processes of skilled engagement. Combining this study of reason with the more recent attention to things within research from materialist and semiotic traditions, I also revive a new sense for the term “representation”, tracing the multiple relationships and shifting identities and differences that are involved in representing. I thus develop a theory of simulation that implies a non-representationalist concept of representing and a non-teleological concept of reason. - 3 - Acknowledgements This is dedicated to Victoria, who made the whole endeavour feasible and life doing it enjoyable. Thanks to all the scientists at the Applied Modelling and Computation Group, without whom this thesis, and the journey its creation has involved, would have been impossible. It was the desire to do justice to their generous donations of time and attention that drove the project toward completion. Thanks also to the Arts and Humanities Research Council for financing the project through a PhD scholarship. Copyright for the images featured in figures 1, 2, 3, 5, 6, 7, 8, and 9 is held by the Imperial College Applied Modelling and Computation Group. Parts of chapter 6 have been previously published1. 1 Spencer, ‘Image and Practice: Visualisation in Computational Fluid Dynamics Research’; Spencer, ‘Trouble with Images in Computational Physics’. - 4 - Table of Contents 1 Introduction.....................................................................................................................9 1.1 Beyond simulacra.................................................................................................9 1.2 Systems of investigation....................................................................................10 1.3 A changing world...............................................................................................12 1.4 Towards a theory of practical reason.................................................................13 1.5 Towards a theory of representation....................................................................16 1.6 Methodological considerations..........................................................................17 2 Doing Science With Simulations.................................................................................23 2.1 Introduction........................................................................................................23 2.2 What is simulation?............................................................................................23 2.3 The history of computer simulation...................................................................26 2.4 Types of simulation............................................................................................29 2.5 Computational laboratories................................................................................30 2.6 Sub-models and coupled models........................................................................33 2.7 History of the Applied Modelling and Computation Group..............................34 2.8 Interdisciplinarity...............................................................................................36 2.9 The finite element method (FEM).....................................................................38 2.10 A multiplicity of simulations............................................................................42 2.11 Visualisation and diagnostics...........................................................................44 2.12 Verification and validation...............................................................................45 2.13 Beyond verification and validation..................................................................50 2.14 Applied modelling and the science of method.................................................51 2.15 Conclusion........................................................................................................53 3 Practice in Theory.........................................................................................................54 3.1 Introduction........................................................................................................54 3.2 Why practice?.....................................................................................................54 3.3 Humans and non-humans...................................................................................56 3.4 The significance of practice...............................................................................58 3.5 The reality of practice........................................................................................60 3.6 Skill....................................................................................................................65 3.7 Temporality.........................................................................................................67 3.8 Objectification....................................................................................................69 3.9 Conclusion..........................................................................................................70 - 5 - - Table of Contents - 4 Reason in Practice.........................................................................................................71 4.1 Introduction........................................................................................................71 4.2 Internalism and externalism...............................................................................72 4.3 Empiricism and rationalism...............................................................................78 4.4 Phenomenotechnique.........................................................................................82 4.5 Reified concepts.................................................................................................84 4.6 Phenomenotechnique in practice.......................................................................85 4.7 Phenomenotechnique in context........................................................................88 4.8 Temporality and reason......................................................................................90 4.9 Conclusion..........................................................................................................91 5 Modelling and Representing........................................................................................92 5.1 Introduction........................................................................................................92 5.2 Theories of theory: syntax/semantics.................................................................93 5.3 Substantive and deflationary theories of representation....................................95 5.4 From vicarship to realisation..............................................................................97 5.5 What kind of thing might represent?................................................................101 5.6 What makes a good representation?.................................................................104 5.7 Modelling as process........................................................................................107 5.8 Representation in simulation............................................................................110 5.9 New kinds of representation.............................................................................115 5.10 Conclusion......................................................................................................117 6 Images in/of Simulation..............................................................................................118 6.1 Introduction......................................................................................................118 6.2 Trouble with images.........................................................................................119 6.3 Beyond representation......................................................................................123 6.4 Discontinuity