Cosmology

Massimi, M. (forthcoming) A philosopher’s look at DES. Reflections on the use of Bayes factor in cosmology, in J. Frieman and O. Lahav (Eds.). The Dark Energy Survey (World Scientific)

In this paper, I look at the DES Year 1 results and in particular I consider the use of the Bayes factor along the Jeffreys scale in DES model selection. I draw attention to some of the advantages but also to some epistemic limits arising from the use of the Bayes factor.


Massimi, M. (2018) Three problems about multi-scale modelling in cosmology. Studies in History and Philosophy of Modern Physics.

The debate in cosmology concerning LambdaCDM and MOND depends crucially on their respective ability of modelling across scales, and dealing with some of the specific problems that arise along the way. The main upshot of this article is to present three main problems facing multi-scale modelling in contemporary cosmology. The LambdaCDM model, which is the standard and by far most successful current cosmological model, faces what I call the ‘downscaling problem’ when it comes to explain some recalcitrant evidence at the scale of individual galaxies, such as the mass-discrepancy acceleration relation (MDAR) and the baryonic Tully-Fisher relation (BTF). While the fast growing development of computer simulations has addressed these problems, nagging worries remain about some of the epistemic limits of these computer simulations in retrieving (as opposed to explaining) the data. The so-called’upscaling problem’ affects MOND and its ability not just to explain but even simply retrieve large-scale structure and galaxy clusters. Recent attempts at extending MOND (EMOND) have had a limited empirical success, and are still far from providing a consistent explanation for possible formation mechanisms at the large-scale structure. Finally, the ‘in between’ scales problem affects proposals designed to achieve the best of both worlds at the meso-scale. This is a fascinating area from a physical and a philosophical point of view, where the main challenge is the ability to have
genuine predictive novelty.

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McCoy, C.D. (2018) Epistemic Justification and Methodological Luck in Inflationary Cosmology. The British Journal for the Philosophy of Science

I present a recent historical case from cosmology — the story of inflationary cosmology — and on its basis argue that solving explanatory problems is a reliable method for making progress in science. In particular, I claim that the success of inflationary theory at solving its predecessor’s explanatory problems justified the theory epistemically, even in advance of the development of novel predictions from the theory and the later confirmation of those predictions.

Download Open Access PDF doi: 10.1093/bjps/axy014

 


McCoy, C.D. (2017) The implementation, interpretation and justification of likelihoods in cosmology. Studies in History and Philosophy of Modern Physics, 62, 19-35

I discuss the formal implementation, interpretation, and justification of likelihood attributions in cosmology. I show that likelihood arguments in cosmology suffer from significant conceptual and formal problems that undermine their applicability in this context.

Download Open Access PDF doi: 10.1016/j.shpsb.2017.05.002