In an ever expanding world, it can be easy to think of our lives as insignificant. But according to David Deutsch, we all possess one skill that gives each of us infinite reach: our ability to attain knowledge. In the final episode of this season dedicated to making a case for optimism, Chris revisits his interview with the father of quantum computing to explore how knowledge first developed, how it sets us apart and how we can use it to shape a more hopeful future.