Cosmology has been, and continues to be, remarkably successful in reconstructing the evolution of the universe over its 13.8 billion years. This success is somewhat surprising, if one examines the standard model of cosmology, ΛCDM ("Lambda-Cold Dark Matter"), in detail. The model incorporates particle physics, general relativity, classical mechanics and several other theoretical frameworks. Moreover, the evidence in support of ΛCDM ranges from large-scale structure surveys and the power spectrum of the anisotropies in the cosmic microwave background, over detailed hydrodynamical simulations, to high-energy physics experiments at particle accelerators.
My dissertation uses a careful study of the recent history of cosmology to develop a new account of how empirical methods and evidence from a wide range of disciplines can be integrated to bear on a model of a complex target system. The starting point is an explication of a so-called method-driven ‘logic’. This logic represents a general structure for justifications of choosing one set of empirical methods over another to probe a given target. Its characterizing features are that (1) an existing method is repurposed to the target, and (2) the description of the target is adapted to the features that the target would need to have in order for the method to be effective.
Elucidating this method-driven logic brings to the forefront various questions about evidence. First, interpreting the results of method-driven experiments is non-trivial: while significant positive results are ambivalent in their warrant for conclusions about the target, negative results warrant secure constraints on the space of possibilities. Second, I broaden the discussion to more general conflicts in evidence in an integrative context. The final chapter draws on the insights from the previous chapters to discuss the use of cosmological evidence in other subfields of physics, thus coming full-circle on the relation between cosmology and its informing disciplines.
Committee: John Norton (chair), Arthur Kosowsky, Sandra Mitchell, James Woodward