Explanatory Cohrence in the Context of the Second Law of Thermodynamics

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Geller, Benjamin David
Redish, Edward F
This thesis examines how undergraduate life science students experience interdisciplinary connections between introductory physics, chemistry, and biology - what the connections look like, how we foster them, and the affect that stems from them. It is about the gaps students experience between their introductory biology, chemistry, and physics coursework, and how we can draw upon students' resources for bridging them. Rather than looking at connections between physics, chemistry, and biology in the abstract, we ground this thesis in the conceptual context of the second law of thermodynamics, a rich domain for interdisciplinary investigation. Near the end of the thesis, we present an interdisciplinary second law curricular thread that leverages the resources our students have for crossing disciplinary boundaries in this context. Our hope is that other instructors will be convinced to embrace a more interdisciplinary treatment of the second law. The context of our study is NEXUS/Physics, a novel introductory physics course for life science students. We unpack the resources that NEXUS/Physics students have for thinking about entropy and spontaneity. We argue that an approach to the second law that emphasizes the interplay of energy and entropy in determining spontaneity (one that involves a central role for free energy) is one that draws on students' resources from biology and chemistry in particularly effective ways. We identify three ways in which students in NEXUS/Physics have meaningfully crossed disciplinary boundaries in the context of the second law: (1) by unpacking biochemical heuristics in terms of underlying physical interactions, (2) by locating both biochemical and physical concepts within a mathematical bridging expression, and (3) by coordinating functional and mechanistic explanations for the same biological phenomenon. These classes form a basis that spans the space of interdisciplinary connections that we have observed. In moments when interdisciplinary gaps are bridged, our students sometimes exhibit positive affect. We look at the source of this affect and how it interacts with disciplinary identity and epistemology. In doing so, we hope to suggest ways of inviting life science students to participate in physics and to see physics as a central tool for making sense of the biological world.