What does E=mc² actually mean? Professors Brian Cox and 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 recreating 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.