Initial Conditions and the Structure of the Singularity in Wave Collision Induced Pre-Big Cosmology

We propose a scenario of pre-big-bang cosmology where the big-bang singularity arises as the result of the interaction of two plane gravi-dilatonic waves propagating in an asymptotically trivial space. We find that inflation arises for a dense set of initial data and argue that plane waves are states of zero gravitational entropy, being thus good candidates to describe the primordial state of the universe.