www.iop.org/resources/videos/lectures/open/page_44448.html NEW our community pages on facebook and google+ join and share cutting edge lectures and debates www.facebook.com/pages/DebatesAndLectures/116019611819249 or plus.google.com/u/0/b/117772575137150380936/ 2010 winner of the Newton Medal, Edward Witten speaks to an audience at the Institute of Physics in London. He helped progress our understanding of the fundamental theories in physics. He touches on gravity, quantum mechanics and string theory.