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 the Q&A video associated with Idea #11, "Renormalization." Mostly it is me trying to say in slightly better ways what I tried to say in the original video. But we also talk a bit about whether virtual particles are real, and whether an effective field theory of gravity can really explain all the data. 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://art.alphacoders.com/arts/view/74769 #science #physics #ideas #universe #learning #cosmology #philosophy #quantum #fields #effectivefieldtheory #renormalization