Black holes happen when you have a super huge, mega-giant amount of stuff --- crammed into a super-tiny, infinitely-small amount of space. AND THEY ARE SUPER COOL!

In this episode, we learn all about what black holes are and how we found out they were real. We talk to a black hole hunter who has discovered supermassive black holes. And we find out what a wormhole is and why it might be really, really, really hard to ever find one -- or travel through it.

Plus: The Moment of Um answers the question: "Why do goat pupils look like slits?"