This thesis is the result of my own work and includes nothing which is the outcome of work done in collaboration except as declared in the preface and specified in the text.It is not substantially the same as any work that has already been submitted before for any degree or other qualification except as declared in the preface and specified in the text.• Chapters 2 and 3 are partly based on H. Gomes, "Same-Diff ?: Part I: Conceptual similarities (and one difference) between gauge transformations and diffeomorphisms," and H. Gomes, "Same-Diff ?: Part II: A compendium of similarities between gauge transformations and diffeomorphisms (2021, unpublished);• Chapter 4 is based on my contributions to: H. Gomes, J. Butterfield, and B. Roberts, "The Gauge Argument: A Noether Reason ", Forthcoming in 'The Physics and Philosophy of Noether's Theorems', Cambridge University Press, (2021);• Chapter 5 is based on joint work: H. Gomes and J. Butterfield: "How to Choose a Gauge?The case of Hamiltonian Electromagnetism ", (2021, unpublished);• Chapter 6 is partly based on H. Gomes, "Holism as the empirical significance of symmetries", European Journal of the Philosophy of Science (2020); H. Gomes, "Noether charges: the link between empirical significance of symmetries and non-separability", Forthcoming in 'The Physics and Philosophy of Noether's Theorems', Cambridge University Press, (2021); H. Gomes, "Gauging the Boundary in Field-space", Studies in the History and Philosophy of Science, (2019); and H. Gomes, "The role of representational conventions in assessing the empirical significance of symmetries", (2020, unpublished).
AcknowledgementsI would like to thank:• The Cambridge International Trust, for the complete funding of the studies that have led to this thesis.• My supervisor and personal hero, Jeremy Butterfield, who patiently guided me through this transition. His generosity of spirit is only comparable to his encyclopedic knowledge of the field; all I can say is that I tried my best to learn on both accounts.• My co-supervisor, Hasok Chang, for ushering me into the wonderful topic of philosophy of science; and Gordon Belot, Jim Weatherall, Aldo Riello, and Bryan Roberts, for many interesting and helpful conversations on the topic of gauge.