Progress in precision cosmology has resulted in an enigmatic picture of the Universe. We live in a "weird" universe that: suddenly is accelerating – attributed to an energy with negative pressure, coined a "dark energy" – a process similar to Big Bang inflation; a universe that seems to be born from extremely improbable Initial Conditions, the Big Bang inflation, and which, around scales of the present horizon – the "edges" of the observable universe-displays many anomalies.
There is no existing theory yet that consistently and successfully explains these outstanding issues. The hope has been that quantum gravity will provide the insight needed for these fundamental problems. At present, string theory is the leading candidate for quantum gravity. As such, it provides the natural framework for addressing the most outstanding questions in theoretical physics, e.g., "Why did the universe start in such an orderly and improbable state?" The major effort in string theory to derive solutions of (3+1)-dimensional worlds that are similar to our universe resulted, during the last 4 years, in not one unique universe but in googleplexes of universes like ours. This multitude of universes was dubbed "the landscape of string theory." The question of what selected our universe in this vast landscape appeared more severe than ever. The surprising discovery of the landscape, in combination with the observed acceleration of the universe at present times, promotes the investigation of the puzzle of the Initial Conditions to be of crucial importance to our understanding of nature.
Here we will discuss a new approach for the problem of the selection of the Initial Conditions for our universe within the context of quantum gravity, which is based on the quantum dynamics of gravitational and matter degrees of freedom as well as testable predictions that can scrutinize the theory. This approach is based on the proposal of allowing the Wavefunction of the Universe to propagate on the landscape background while incorporating the issue of decoherence of our universe from the rest.
Table of ContentsDark Energy and Dark Matter hidden in the Geometry of Space?.- The Arrow ot Time In a Universe with aPositive Cosmological Constant.- The Future History of the Universe.- The Return of a Static Universe and the End of Cosmology.