In this episode, John and Katie take a break from talking through the universe's timeline to focus on a mystery of our cosmos: black holes.Head to https://policygenius.com/crashcourse to get your free life insurance quotes and see how much you could save. This show is a production of Complexly. If you want to help keep Crash Course free for everyone, forever, you can join our community on Patreon at  http://www.patreon.com/crashcourse See Privacy Policy at <a href="https://art19.com/privacy" rel="noopener noreferrer" target="_blank">https://art19.com/privacy</a> and California Privacy Notice at <a href="https://art19.com/privacy#do-not-sell-my-info" rel="noopener noreferrer" target="_blank">https://art19.com/privacy#do-not-sell-my-info</a>.

Ep. 6: The Story of Dark Matter

Dr. Katie Mack, a theoretical astrophysicist, walks #1 New York Times bestselling author John Green through the history of the entire universe - including the parts that haven’t been written yet.