Speaker: Andrew Liddle
Title: Interpreting DESI's evidence for evolving dark energy
Room: 3024
Host: John Terning
Abstract: We are all bored with LambdaCDM and seeking new cosmological physics to explore. For a decade the Hubble tension has been motivating vast numbers of new physics proposals, while this year the DESI collaboration claimed `tantalising hints’ of dark energy evolution from combined cosmic microwave background, baryon acoustic oscillation, and supernova data. We analyse both these lines of evidence from a Bayesian perspective. We argue that reduced tension alone cannot be used a robust signature of new physics, and that the best-fit evolving dark energy models create a new form of cosmic coincidence. In each case careful assessment of model and parameter priors is crucial, and models capable of fitting the data appear a priori unlikely.
