Speaker
Description
It is often argued that anomalies and tensions in current theories reveal where they might be lacking and "hint at" future theories. While this may hold true for some historical cases, I argue that the current "precision tension era” (Di Valentino, Said, and Saridakis, 2025) in cosmology—typified by the Hubble and S8 tensions—has a different character. These tensions indicate that ΛCDM is lacking, but do not provide guidance for where the problem lies or criteria for evaluating the pursuit-worthiness of alternative theoretical proposals. The result is a clear mapping of the possibility space by theorists and a huge proliferation of viable theoretical proposals but no consensus on any particular proposal. Given that tensions are not providing the theoretical guidance often expected in such situations, a natural response might be to adopt an eliminative strategy wherein proposals are evaluated by their ability to resolve the tension and eliminated if they cannot. Comparative approaches, such as the "H0 Olympics" pursued by Schöneberg et al. (2022), exemplify this tendency to evaluate models individually. While initially appealing, I argue that this approach assumes a stability and modularity to the tensions that they do not actually exhibit. Instead, I advocate for a compositional approach wherein proposals are assessed by their contributions to alleviating the tension and their compatibility with other proposals. Such an approach pushes cosmologists to consider how proposals might jointly work to resolve tensions and may, counterintuitively, favor more flexible approaches that are sometimes dismissed as ad hoc.