Psycho - Season 1 Episode 2 Episodul 2

This ground-breaking two-part series takes us inside two of the most amazing structures in the natural world: our hands and feet.

Hannah Fry takes a spectacular look at the science of size by imagining a parallel world in which everything is made bigger or smaller.

Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before.

Dr Helen Czerski examines the world of sound waves.