BBC Earth asked a group of mathematicians and physicists to tell them their favourite equations. You can vote for your favourite equation here:
http://www.bbc.com/earth/story/20160120-you-decide-what-is-the-most-beautiful-equation-ever-written
Dr Clare Dunning’s favourite is the Yang-Baxter equation. To find out about it, watch the stop motion animation on the website, and ask Clare if you want to know more.