The Biggest Ideas in the Universe is a series of videos where I talk informally about some of the fundamental concepts that help us understand our natural world. Exceedingly casual, not overly polished, and meant for absolutely everybody. This is Idea #23, " Criticality and Complexity." Having spend a lot of time on the basic ingredients of our universe, it's time to contemplate how they come together to make complex systems. The idea of critical behavior -- things happening at all spatial scales -- is an important organizing principle. My web page: http://www.preposterousuniverse.com/ My YouTube channel: https://www.youtube.com/c/seancarroll Mindscape podcast: http://www.preposterousuniverse.com/podcast The Biggest Ideas playlist: https://www.youtube.com/playlist?list=PLrxfgDEc2NxZJcWcrxH3jyjUUrJlnoyzX Blog posts for the series: http://www.preposterousuniverse.com/blog/category/biggest-ideas-in-the-universe/ Background image: https://en.wikipedia.org/wiki/Wikipedia:Wiki_Science_Competition_2017_in_the_United_States/Results#/media/File:The_Galaxy_Within.jpg #science #physics #ideas #universe #learning #cosmology #philosophy #complexity #criticality