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Mass and Moles

Marcus du Sautoy explores the history of Le Grand K - the world's master kilogramme - and the race to replace it now that it has been discovered to be losing weight.

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.

1 hour



Role Contributor
Presenter Marcus du Sautoy
Director Mike Cunliffe
Producer Mark Woodward