Precision: The Measure of All Things (2013) Part 2 Mass and Moles

Precision: The Measure Of All Things

Marcus du Sautoy shows how precision measurement has helped to define and advance civilisation. It has taken us from Stone Age Skymaps to the exploration of outer space. Packed with cutting-edge science and jaw-dropping examples from the modern world, this is a journey from sundials to time lords and lasers.

Part 2: Mass and Moles

Deep underground in a vault beneath Paris lives the most important lump of metal in the world - Le Grand K. Created in the 19th century; it's the world's master kilogramme, the weight on which every other weight is based. But there is a problem with Le Grand K - it is losing weight. Professor Marcus du Sautoy explores the history of this strange object and the astonishing modern day race to replace it.

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