David Pogue sets out on a worldwide quest to find the key molecules and chemical reactions that have paved the way for human civilization, life, and even the universe as we know it. Stream all three episodes of NOVA l PBS' “Beyond the Elements” now on the PBS Video app. | PBS

Scientists are learning how we can edit memories—and delete our worst fears. Catch "Memory Hackers," airing February 10 at 9/8c on PBS: http://to.pbs.org/1TGyRi1 | NOVA l PBS