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 for Idea #18, "Atoms." A bunch of good questions this week. Why certain particles decay into other ones, can there be negative-mass particles, and how do we know there aren't noticeable forces we haven't yet discovered? There's even a plot of experimental constraints! 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: http://physicsopenlab.org/2017/05/18/particles-in-the-mist/ #science #physics #ideas #universe #learning #cosmology #philosophy #particles #atoms