Now! High quality version at https://www.youtube.com/watch?v=P1ww1IXRfTA Physicist Richard Feynman thinks aloud about atoms and how they 'jiggle', and how we perceive that jiggling as 'hot' and 'cold'. From the BBC TV series 'Fun to Imagine'(1983). You can now watch higher quality versions of some of these episodes at www.bbc.co.uk/archive/feynman/