The first 100 people to go to https://blinkist.com/stevemould will get unlimited access for 1 week to try it out. You'll also get 25% off if you want full membership. Have you noticed the shape of your urine stream when you pee? It does this twisty undulating thing. But why? And why do the same waves appear when you pour a liquid from a container? Here's my video featuring Rayleigh instability: https://www.youtube.com/watch?v=DvtbQs7hWXw Here's my video about the Lattice Boltzmann Method: https://www.youtube.com/watch?v=qwPg2Dmh-6k The fake medical advice at the end comes courtesy of not-fake Doctor Rohin Francis. This is his excellent channel: https://www.youtube.com/channel/UCgRBRE1DUP2w7HTH9j_L4OQ Here are a couple of good videos on laminar flow: https://www.youtube.com/watch?v=y7Hyc3MRKno https://www.youtube.com/watch?v=5LI2nYhGhYM Image and video credits: The video of water floating in microgravity is by NASA The Lattice Boltzmann animation is by Richard Sear You can buy my books here: https://stevemould.com/books You can support me on Patreon here: https://www.patreon.com/stevemould just like these amazing people: Matthew Cocke Glenn Watson Joseph Rocca Joël van der Loo Doug Peterson Rashid Al M Paul Warelis Will Ackerly Heather Liu Alnitak Twitter: http://twitter.com/moulds Instagram: https://www.instagram.com/stevemouldscience/ Facebook: https://www.facebook.com/stevemouldscience/ Buy nerdy maths things: http://mathsgear.co.uk/