In our last episode, Dr. Katie Mack and John Green discuss what the ultimate fate of the universe might look like.  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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

In this episode, Dr. Katie Mack gives John Green an idea of what to expect for the future of our universe.  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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

In our journey through the history of the entire universe, we have finally reached the present. Before we continue moving forward in our timeline, John has some questions for Katie that he's been holding back.  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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

In this episode, Katie Mack and John Green discuss why life was able to happen.  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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

In this episode, Katie Mack and John Green discuss the wonder keeping the stars apart... dark energy. 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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

"How do we know that dark matter is there?"   In this episode, Dr. Katie Mack and John Green unpack the full story of dark matter. 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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

"Is free will still in the equation?" In this episode, the universe begins to become visible to itself. Dr. Katie Mack teaches John Green about the moment the stars turned on, while John seeks to answer one question... do humans matter to the universe?  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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

"The only thing that could have happened, happened"  In this episode, the universe as we know it starts to come into focus. Dr. Katie Mack teaches John Green about the cosmic dark ages, the possibility of a multiverse, and the connection between the hot, dense early universe and today. 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 https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

"That’s why we’re here. Something broke." Head to https://policygenius.com/crashcourse to get your free life insurance quotes and see how much you could save.  In episode 2 of their journey through the history of the universe, Dr. Katie Mack and John Green discuss the fundamental forces of nature, the tiny ovens we know as particle colliders, and how we all can exist. See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.