A structured analysis of Hubble tension

Abstract: As observations of the Hubble parameter from both early and late sources have improved, the tension between these has increased to be well above the 5$\sigma$ threshold. Given this, the need for an explanation of such a tension has grown. In this paper, we explore a set of 7 assumptions, and show that, in order to alleviate the Hubble tension, a model needs to break at least one of these 7, providing a quick and easy to apply check for new model proposals. We also use this framework to make a rough categorisation of current proposed models, and show the existence of at least one under-explored avenue of alleviating the Hubble tension.