What does E=mc2 actually mean? Dr. Brian Cox and Professor Jeff Forshaw go on a journey to the frontier of twenty-first century science to unpack Einstein's famous equation. Explaining and simplifying notions of energy, mass, and light,while exploding commonly held misconceptions,they demonstrate how the structure of nature itself is contained within this equation. Along the way, we visit the site of one of the largest scientific experiments ever conducted: the now-famous Large Hadron Collider, a gigantic particle accelerator capable of re-creating conditions that existed fractions of a second after the Big Bang. A collaboration between one of the youngest professors in the United Kingdom and a distinguished popular physicist, Why Does E=mc2? is one of the most exciting and accessible explanations of the theory of relativity.