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Speculating About the Universe Speculating About the Universe What the history of cosmology tells us about the role of speculation in theory development Michael D Schneider 2014 Table of Contents I. A Curious Science ...................................................................................................... I-3 Networks And (Scientific) Objects .............................................................................. I-7 II. A History Of A Science ......................................................................................... II-25 Going Down The Rabbit Hole And Into Descartes' Vortices ................................... II-27 Newton’s Backyard ................................................................................................... II-32 Once Upon A Spacetime ........................................................................................... II-36 The Mathematical Cosmogony Of Modern Cosmology ........................................... II-44 Kindling A Universe ................................................................................................. II-50 Steady As She Goes .................................................................................................. II-53 Economics And (Cosmological) Inflation ................................................................. II-67 Wrapping Up ............................................................................................................. II-85 III. A Speculative Theory .......................................................................................... III-88 The Darwinian Response ......................................................................................... III-95 The Popperian Response ........................................................................................ III-103 The Semi-Stable Set Response: .............................................................................. III-115 The Attention Economy Response: ........................................................................ III-132 In Summary, As Well As Some Concluding Remarks .......................................... III-152 IV. Works Cited ..................................................................................................... IV-157 I-2 I. A Curious Science The topic of this essay concerns the role of speculation in the development of scientific theory, with a particular focus on the history of modern cosmology. Insofar as the argument concerns general science methodology, the attention given to the development of cosmology comes as a thorough case study of a field particularly known for its speculative claims. I will argue in this chapter that, due to certain characteristics of the field, cosmology merits particular treatment within the philosophy of science. The scope of cosmology renders it an excellent conceptual playground to witness how speculation contributes to theory development, often driving the field. It seems that, at least in fields underconstrained by data, theoretical work performs an analogous role to experimental observation, which is to say that speculation can rightfully be described as conferring support for a scientific theory. Furthermore, the support it provides to theories is distinct from traditional notions of evidence. While the arguments made in this essay concern the role of speculation broadly in science methodology, focusing on the development of cosmology gives many examples of the potential success of speculations, motivating an investigation into the nature of speculative claims. As the title of this introductory chapter suggests, this essay focuses exclusively on the efforts and progress of scientific cosmology, and any similarities borne by theological or literary cosmologies are incidental. Insofar as each of these cosmological traditions may thrive on speculations, the former is at the very least characterized by mathematics, and it is challenged, as remains to be seen, to use emergent data so as to reduce the number of speculative claim, rather than increase their number. From another perspective, the former is cultivated by a subset of physicists, which earns I-3 it a sociological distinction among the sciences. I follow the tradition that calls the field “scientific cosmology”, but the other popular phrase is “physical cosmology”. For several reasons that will become clear in this chapter, the use of “physical”, I feel, misleads more than it clarifies. Before I begin, I wish to make a personal note in regards to the content of this essay. The project that eventually resulted in these pages was kindled by a certain incredulity toward the field of cosmology. I knew the field for some of its more exotic claims, and the spectacular reach of those claims amazed me. And perhaps for the same reason, they also made me dubious, suspicious that such far-reaching claims could nonetheless constitute science, in the same way that one might characterize the acidity of a chemical solution or the fracture point of a crystal. Because I trust, at first pass, that the community of cosmologists earnestly pursues scientific theories, I funneled my suspicions not toward the legitimacy of their theories as constituting scientific work, but toward my conception of science generally. I wanted to identify a characterization of science that readily explains how cosmological theory can develop so successfully alongside the other sciences. Upon examination, it occurred to me that the largest conceptual discrepancy between cosmology and other scientific disciplines is the availability of useable data. Cosmologists seem adept at pushing theory forward and refining descriptions of the universe, even while they lack any particular new data to drive that progress. For this reason, I began exploring the question of how theorists come up with their theories, in light of their research environments, regardless of whether those environments are data- plenty or data-weak. I had hoped to develop a plausible justification for treating I-4 speculation and theory development seriously, independent of data-driven expectations that further refine the process. In that mindset, this essay was born. The role of the introductory chapter is twofold. First, I intend to provide an operational definition of “scientific cosmology”, at least according to some uncontroversial remarks about what a complete theory of cosmology might look like. This goal is merely prudent housekeeping, in anticipation of the history of the field presented in the second chapter. The more critical purpose of this chapter, therefore, is to introduce a long-form metaphor of science as a dynamic, evolving network of conceptual artifacts, which is self-similar at many scales. These interconnected networks of science, which I have labeled “networks of dependencies,” emphasize a theory-first approach to science: evidential relationships connect conceptual objects that stand in for scientific theories. The advantage of a theory-first picture of science will be that it provides us a vocabulary by which we are able to track speculative developments in underdetermined research areas. In these situations, traditional accounts of evidence-mediated theory selection cannot possibly capture all of the successes in theory development. Cosmologists, philosophers, and historians of science alike should be quite familiar with this underdetermined class of situations. Following chapter 1, chapter 2 is dedicated to the development of contemporary cosmology, tracing briefly the major historical theories and the transitions between them. The chapter is technical to a degree, but no particular background in physics is expected of the reader. A significant portion of chapter 2 focuses on the early developments of inflationary cosmology, which reoriented the past several decades of early-universe cosmology research, and has since resulted in a wide class of inflationary theories. Announcements in the past year concerning the I-5 BICEP2 telescope at the South Pole have generated much excitement and controversy over the evidential status of inflationary theories. The purported discovery by the BICEP2 Collaboration came in the middle of my research toward this paper, and its theoretical implications and ensuing controversy in the community rekindle many of the concerns and questions that motivate my arguments. These are stirring times, indeed. Given the present popular excitement with cosmology, as well as the public interest in contemporary breakthrough science, it is a sad fact that students of the various sciences are considerably underexposed to the historical developments that have culminated in the contemporary theories they are taught. In the case of cosmology, a critical eye toward past theoretical developments reveals certain methodological trends that transcend any individual treatments of data and mathematics. A primary goal of chapter 2 is to reveal those trends in the midst of historical exposition. The final chapter, chapter 3, is intended to engage philosophers on two levels. In one sense, I want to impress on philosophers that cosmology is a field worthy of particular consideration because of its historical successes, despite the field’s difficulties in accessing new data. Conjoined with this goal, more generally I hope to motivate philosophers interested in questions of science methodology to take more seriously the role of speculation in scientific theory development. At the start of the chapter, I pose a question concerning how a theorist speculates on new theory
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