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

"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

"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

"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.

"Part of me was there?"

Dr. Katie Mack teaches John Green about the beginning of the Universe - including that we are not just made of stardust; we are also made of Big Bang stuff, with pieces of us directly born in the vast, first cacophony.

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