Why is the tallest building on earth less than half a mile high? Why don't we have mountains as tall as those on Mars?
In the last of this year's Christmas Lectures, Dr Mark Miodownik investigates the world of the very big and very tall. He reveals that, at this scale, everything is governed by a battle with one of the strangest forces in the universe - gravity.
With help from acrobats, levitation devices, spiders, birthday cake candles and even some sticky goo, Mark discovers how gravity can make solid rock behave like a liquid and investigates whether one day it might be possible to build a structure from Earth into space, taking us beyond the reach of gravity without the use of rocket.
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Ready to Watch Royal Institution Christmas Lectures, Season 45, Episode 3?