Here's another paper http://inspirehep.net/record/221659?ln=en On the Creation of an Inflationary Universe From 'Nothing' in a Higher Dimensional Theory of Gravity With Higher Derivative Terms Abstract (Elsevier) The universe may been created from “nothing” as a quasi-de Sitter space-time, by a process of quantum tunnelling. The probability P for such a tunnelling process to occur is proportional to exp(−| S E |)m where S E is the euclidean action. The maximum probability corresponds to a configuration with S E = 0. This idea can be realized in a higher-dimensional theory of gravity with higher-derivative terms, in which a scalar field φ arises as the inverse radius function of the internal space. Subsequent evolution of the field φ may permit inflation.