Alan Davies and Marcus du Sautoy visit a length bar interferometry unit and use a laser tracker to measure Alan's length of string.
Comic Alan Davies attempts to answer the proverbial question: how long is a piece of string? But what appears to be a simple task soon turns into a mind-bending voyage of discovery where nothing is as it seems. An encounter with leading mathematician Marcus du Sautoy reveals that Alan's short length of string may in fact be infinitely long. Ultimately, Alan finds that measuring his piece of string could - in theory at least - create a black hole, bringing about the end of the world.
Ninety million miles away from us is the power that shapes our world - the sun. We see it shine in the sky above us, but beyond our sight something dramatic is happening - the sun is going into overdrive. It's more active now than it's been for a decade, sending eruptions of super-heated plasma and vast waves of radiation towards our planet, with the potential to disrupt our lives in dramatic ways. Using the latest satellite images, and the expertise of Britain's leading solar scientists, Kate Humble and Helen Czerski reveal the inner workings of our very own star, and the influence its mysterious cycles of activity have on our planet.
Brian Cox explains how we can discover what stars are made of by analysing the light that arrives on earth from the stars. Elements are shown to emit certain colours when they are burnt.