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.

Dr Mark Miodownik zooms into the microscopic world beneath our fingertips. In this unfamiliar landscape, strange forces dominate the world and common sense goes out of the window. He reveals how this tiny hidden world can make objects behave like magic, and discovers the secrets of the extraordinary metals that make jet engines possible. With a mass audience taste test, Mark reveals why chocolate is actually one of the most sophisticated and highly engineered materials on the planet, using special crystals designed to melt in the mouth. He looks forward to new era of self-healing materials where a broken mobile phone or car bumper could heal itself and how, one day, material scientists might even create artificial life.

How can a hamster survive falling from the top of a skyscraper, ants carry over 100 times their own body weight and geckos climb across the ceiling? In the first of this year's Christmas lectures, Dr Mark Miodownik investigates why size matters in animal behaviour. He reveals how the science of materials - the stuff from which everything is made - can explain some of the most extraordinary and surprising feats in the animal kingdom. By the end, you will understand why you will never see an elephant dance.