In our last episode, Dr. Katie Mack and John Green discuss what the ultimate fate of the universe might look like. 

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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 

In this episode, Dr. Katie Mack gives John Green an idea of what to expect for the future of our universe. 

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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 

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. 

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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 

In this episode, Katie Mack and John Green discuss why life was able to happen. 

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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

In this episode, Katie Mack and John Green discuss the wonder keeping the stars apart... dark energy.

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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 

"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.

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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 

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.

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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? 

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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.

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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."

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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.