"The Big Sink"

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.

In our journey through the history of the entire universe, we have reached the present. Before we continue moving forward in our timeline, John has some questions for Katie that he's been holding back.

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.

Chapters:
Introduction
CMB & The Cosmic Web
The Possibility of a Multiverse
The Inflaton Field
Viewing Early Galaxies
The Surface of Last Scattering
The Dark Ages of the Cosmos
Dark Matter & Cosmic Dawn
Feeling Awe

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.

Chapters
- Introduction
- There Shouldn’t Be Stuff
- The Big Bang Theory
- We’re Not Sure About The Singularity
- Cosmic Inflation
- The First Second
- The First Two Minutes
- Outro

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

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

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

Chapters
Introduction
The Elements We're Made Of
Our Solar System Forms
Life on Earth
Life on Other Planets
The Human Pursuit of Understanding

Introducing the very first Crash Course Podcast! Over the next 11 episodes, John Green and Katie Mack will walk through the entire history of the universe… even the parts that aren’t written yet.

"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.

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

Chapters
- Introduction
- Reviewing our Timeline
- Reviewing Redshift & Introducing the Hubble Tension
- Cosmic Noon & Galactic Archaeology
- The Universe's Rate of Expansion
- Dark Energy & The Cosmological Constant
- Poetry in the Astrophysics Podcast
- Outro

"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?

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.

Chapters
- Introduction
- Particle colliders
- Protons
- The Fundamental Forces
- The Theory of Everything
- The Higgs Field
- It's Incredible That We Know This Stuff