Inflationary models of the primordial universe
This chapter addresses the problem of fine-tuning the initial conditions of the previous chapter’s hot Big Bang model, so that the universe has the observed properties, as well as the problem of the origin of large-scale structure. It shows that these problems are related to each other, and can be solved by assuming a period of accelerated expansion in the earliest history of the universe. Since the 1980s, the general acceptance of this idea of a primordial inflationary phase can be considered as the third phase in the history of the development of relativistic cosmology. The chapter first outlines the issues with the hot Big Bang model: the flatness problem; the Big Bang horizon, and monopole problems; and the problem of the origin of the large-scale structure. It then provides a solution in the form of inflation, and goes on to discuss ‘chaotic’ inflation.