Why is the Universe so Dark?

<strong>Seminar of the School of Physical Sciences -------------------------------------------------</strong> Title: <strong>Why is the Universe so Dark?</strong> Speaker: <strong>Mohammad Sami</strong> (Jamia Millia Islamia, New Delhi) Date: <strong>September 2, 2015</strong> <strong>Abstract:</strong> In this presentation for a general audience, I will briefly mention the shortcomings of the Standard Model of universe. After that I will focus on the late time inconsistency of the model, dubbed the age crisis, whose resolution requires the presence of a repulsive effect that could be sourced either by dark energy or by a large scale modification of gravity. By and large, our description is based upon Newtonian cosmology which is simple and elegant despite its limitations. On heuristic grounds, I will explain how a tiny mass of the graviton could account for late time cosmic acceleration.