An RAS Public Lecture: The Unknown UniverseDr Stuart Clark(Geological Society Lecture Theatre) It is less than a century since Albert Einstein gave the world the mathematical tools to understand the Universe. In that time, astronomers have developed the theory that our cosmos was born in a titanic release of energy about 14 billion years ago. But why can't they fully prove this Big Bang theory? What pieces are missing from this puzzle and when might we uncover them? This talk will explain the great discoveries we have made, the mysteries still to solve and the questions that we may never be able to answer about the birth of our Universe. Dr Stuart Clark is an award-winning journalist and author. He is a visiting fellow of the University of Hertfordshire and a Fellow of the Royal Astronomical Society. He holds a first class honours degree and a PhD in astrophysics. He is a consultant for New Scientist and writes The Guardian's astronomy blog, Across the Universe. His book The Sun Kings was short-listed for the The Royal Society's popular science book prize in 2008. In 2013, he was named European astronomy journalist of the year. Copies of his latest book, The Unknown Universe will be available at the lecture.