The beautiful math behind six degrees of separation. Sponsored by Incogni - use code veritasium at https://incogni.com/veritasium to get an exclusive 60% off. If you’re looking for a molecular modelling kit, try Snatoms, a kit I invented where the atoms snap together magnetically - https://ve42.co/SnatomsV Sign up to the Veritasium newsletter for weekly science updates - https://ve42.co/Newsletter To play around with the simulations in the video, you can follow these links: Disease spreading - https://www.veritasium.com/simulation2 Preferential attachment - https://ve42.co/barabasiAlbertSim ▀▀▀ A huge thank you to: Duncan Watts, for creating the small-world model that inspired this video and expanding on his further work; Steve Strogatz, for telling the story with such clarity & humour; Albert-László Barabási, for revealing the the inevitability and impact of hubs; Mark Buchanan, for his insightful takeaways that pulled it all together. Check out Duncan Watts’ books here - https://www.amazon.com/Six-Degrees-Science-Connected-Age/dp/0393325423 Check out Mark Buchanan’s book here - https://ve42.co/bookNexusWorlds ▀▀▀ Chapters: 0:00 What is six degrees of separation? 4:23 Network Shortcuts 7:11 The Strength of Weak Ties 8:20 Proving it’s a small world 10:39 How quickly can disease spread? 12:36 Strogatz goes viral 16:59 What is a network hub? 18:23 Preferential Attachment 23:38 The Prisoner’s Dilemma 28:22 Your behavior can change the world’s ▀▀▀ References can be found here - https://ve42.co/networksRefs Image and video references can be found here - https://ve42.co/networksVisuals ▀▀▀ Special thanks to our Patreon supporters: Alex Porter, Alexander Tamas, Anton Ragin, Anupam Banerjee, Gnare, Ibby Hadeed, Jon Jamison, Juan Benet, Lee Redden, Meekay, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Ubiquity Ventures, Adam Foreman, Albert Wenger, armedtoe, Balkrishna Heroor, Bertrand Serlet, Blake Byers, Bruce, Dave Kircher, David Johnston, David Tseng, Evgeny Skvortsov, Garrett Mueller, gpoly, Jeromy Johnson, KeyWestr, Kyi, Marinus Kuivenhoven, Matthias Wrobel, meg noah, Michael Bush, Michael Krugman, Robert Oliveira, Tj Steyn & wolfee ▀▀▀ Writers: James Moore, Casper Mebius & Derek Muller Producer & Director: James Moore Editors: Peter Nelson & Jack Saxon Camera Operators: Derek Muller & Casper Mebius Animators: Andrew Neet, Emma Wright, Fabio Albertelli & Ivy Tello Illustrators: Jakub Misiek Assistant Editor: James Stuart Researchers: Callum Cuttle, Aakash Singh Bagga & Gabe Strong Simulations: Callum Cuttle, Gabe Strong & Ivy Tello Sound Designers: Pavle Peric & James Stuart Thumbnail Designers: Abdallah Rabah, Ren Hurley & Ben Powell Production Team: Josh Pitt, Nicola Griffiths & Rob Beasley Spence Executive Producers: Derek Muller & Casper Mebius Additional video/photos supplied by Getty Images, Storyblocks Music from Epidemic Sound