The inflationary paradigm, for the description of the first moment in the history of the universe stands strongly, since it solves several problems that a description of the evolution of the universe without any inflationary era is not able to solve. However, more than a hundred different inflationary universe models have been developed. We need to eliminate as many as possible in order to obtain a greater knowledge of the initial era of the universe. In this volume of the journal Universe we invite researchers to collect observational results and confront them with the predictions of different inflationary models in an effort to falsify as many as possible. Additionally, we invite theoreticians to judge the strength of different inflationary models—which have a sound physical basis and which are ad hoc ‘toy models’.
Prof. Oyvind G. Gron