ABSTRACT
This chapter discusses the list of problems and then addresses them with a silver bullet, the theory of cosmic inflation. It begins with two generic and fundamental challenges of the Hot Big Bang model, namely the horizon and flatness problems. The flatness and horizon problems of the Hot Big Bang are generic and inescapable. The horizon and flatness problems are overcome by all inflationary models, because their resolution is due to the idea of inflation itself. In contrast, the production of the density perturbations, even though also a generic prediction of inflation, results in perturbations with characteristics that are dependent on the inflation model considered. Inflation produces the primordial density perturbations through a process called particle production that arises from considering the superluminal expansion of space in conjunction with the notion of the quantum vacuum. Superluminal expansion during inflation results in superhorizon correlations.
