In the last decade we have started to answer ageo-old questions like the age of the Universe and what it contains. Hiranya Peiris unravels the detective story, explaining what we know and how we know it. Watch the Q&A: https://youtu.be/63JbKXfedRE Subscribe for regular science videos: http://bit.ly/RiSubscRibe Modern fundamental physics contains ideas just as revolutionary as those of Copernicus or Newton; ideas that may radically change our understanding of the world; ideas such as extra dimensions of space, or the possible existence of other universes. Testing these concepts requires enormous energies, far higher than what is achievable by the Large Hadron Collider at CERN, and in fact, beyond any conceivable Earth-bound experiments. However, at the Big Bang, the Universe itself performed the ultimate experiment and left clues and evidence about what was behind the origin of the cosmos as we know it, and how it is evolving. And the biggest clue is the afterglow of the Big Bang itself. In the past decade we have been able to answer age-old questions accurately, such as how old the Universe is, what it contains, and its destiny. Along with these answers have also come many exciting new questions. Join Hiranya Peiris to unravel the detective story, explaining what we have uncovered, and how we know what we know. Hiranya Peiris is Professor of Astrophysics in the Astrophysics Group in the Department of Physics and Astronomy at University College London. She is also the Principal Investigator of the CosmicDawn project, funded by the European Research Council She is also a member of the Planck Collaboration and of the ongoing Dark Energy Survey, the Dark Energy Spectroscopic Instrument and the Large Synoptic Survey Telescope. Her work both delves into the Cosmic Microwave Background and contributes towards the next generation galaxy surveys that will yield deep insights into the evolution of the Universe. The Ri is on Twitter: http://twitter.com/ri_s