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 #5, "Time." We talk about what time is, whether it's "real," and about why it seems to move in just one direction. That gets us a bit into entropy, which is a teaser for a later video in the series. 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/watch?v=HI09kat_GeI&list=PLrxfgDEc2NxZJcWcrxH3jyjUUrJlnoyzX&ab_channel=SeanCarroll Blog posts for the series: http://www.preposterousuniverse.com/blog/category/biggest-ideas-in-the-universe/ Background image: https://commons.wikimedia.org/wiki/File:Czech-2013-Prague-Astronomical_clock_face.jpg #science #physics #ideas #universe #learning #cosmology #philosophy #math #time