Initial Conditions in Pre-Big Bang String Cosmology

摘要

One of the most interesting differences between the pre-big bang scenario and the211u001estandard cosmological models is in the description of the initial state of the 211u001euniverse. Contrary to the basic paradigm of modern cosmology, in the pre-big bang 211u001emodel the universe is initially in a classical state, the most general 211u001eperturbative solution of the tree-level low-energy effective string action. The 211u001eauthors discuss here the naturaliness of this initial state and the conditions 211u001ethat the initial classical fluctuations should satisfy in order to generate an 211u001einflationary phase. The authors argue that the occurrence of a period of 211u001einflation in this scenario is as generic in string theory as that of 211u001egravitational collapse in general relativity.