cosmology strings vs loops How well does string cosmology account for inflation, CMB, gravitional waves, evolution classically using FRW metric? does string cosmology offer either qualitative or quantitative predictions? This paper addresses these in the loop framework, http://arxiv.org/abs/1003.4660 Inflation in loop quantum cosmology: dynamics and spectrum of gravitational waves Jakub Mielczarek, Thomas Cailleteau, Julien Grain, Aurelien Barrau 11 pages, 14 figures (Submitted on 24 Mar 2010) "Loop quantum cosmology provides an efficient framework to study the evolution of the Universe beyond the classical Big Bang paradigm. Due to holonomy corrections, the singularity is replaced by a "bounce". The dynamics of the background is investigated into the details, as a function of the parameters of the model. In particular, the conditions required for inflation to occur are carefully considered and are shown to be generically met. The propagation of gravitational waves is then investigated in this framework. By both numerical and analytical approaches, the primordial tensor power spectrum is computed for a wide range of parameters. Several interesting features could be observationally probed.