Turing's Cake (and other wrinkly math)

Tiger skin cake is named after its intricate striped patterns, but they might be more than just decoration. I have a hunch that this cake is an example of a Turing pattern, the same mathematical model that gives a pufferfish its spots and your brains its wrinkles. We'll learn about Turing patterns and how to simulate them, mathematical models for wrinkling surfaces, and the Swift-Hohenberg equation that was first used to describe convection -- or, at least that's how we thought it was first discovered... Become a Patreon member: https://www.patreon.com/PhysicsfortheBirds 0:00 Intro 0:38 Patterns in Nature 2:15 Simulating Reaction-Diffusion 4:50 Cake Game Plan 6:29 Why are wrinkles wrinkly? 9:53 Turing's Unpublished Work 11:26 Conclusion Thank you to Caleb Birtwistle for captioning! Turing's paper: https://www.dna.caltech.edu/courses/cs191/paperscs191/turing.pdf Reaction-Diffusion in nature: https://www.science.org/doi/10.1126/science.1179047 Mbu Pufferfish: https://www.youtube.com/watch?v=T83pQ825-Bs Simulating Reaction-Diffusion: https://www.karlsims.com/rd.html Gray-Scott Model: https://groups.csail.mit.edu/mac/projects/amorphous/GrayScott/ Zebrafish Patterns: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689028/ Tiger Skin Cake Recipe: https://www.youtube.com/watch?v=Ich__KlBnWs Why fingers wrinkle: https://royalsocietypublishing.org/doi/10.1098/rsbl.2012.0999 Math of wrinkles: https://www.sciencedirect.com/science/article/abs/pii/S0022509608000380 Math of wrinkly spheres: https://math.mit.edu/~dunkel/Papers/2015StEtAl_NatMat.pdf Turing-Swift-Hohenberg EQ: https://www.researchgate.net/publication/347410560_Labyrinthine_patterns_transitions Turing's unpublished notes: https://www.sciencedirect.com/science/article/pii/S0315086015000397 Patterns in paint blog: http://www.pforbes.org/blog/turing-patternms-in-paint