The Hunt for Black Holes with Karl Gebhardt

How do black holes work? And how do we learn about them, when they're impossible to see?

Karl Gebhardt is one of the world's top experts when it comes to black holes. He's a professor of astrophysics at the University of Texas. In his career, he's helped find half of the 80 known black holes in the universe. One of them was the biggest black hole known in the universe - 17 billion times heavier than the sun!

Dr. Gebhardt is now working on an experiment called HETDEX, or the Hobby-Eberly Telescope Dark Energy Experiment. That's what all the spectrographs were for when Sara visited his lab! He's looking for another dark, hard to see and understand mystery in space, dark energy. If you listened to our episode on dark energy, you know that astronomers know very little about dark energy. Dr. Gebhardt hopes that HETDEX will help explain what makes up almost three-quarters of all the matter and energy in the universe.

If you'd like to learn more about black holes, there's so much more to find out! Our favorite video about black holes takes you on one of the wildest journeys in the universe. YouTuber VSauce takes you inside a black hole, with some incredible visualizations. It's truly mind blowing (imagine being able to see the back of your head when you're looking right in front of you)! There's also our favorite scientific word, "spaghettification." As you might guess, you don't want to experience it.

Keep in mind, these are all theories. No one knows exactly what goes on inside a black hole. This BBC article also does a good job explaining what may and may not be true inside a black hole! WIRED has a brief history of mind-bending ideas about black holes, starting with the visionary astronomer John Mitchell in 1784.

If you'd like a slightly shorter explanation, take a Crash Course in Astronomy in under two minutes.

What are your mind-bending ideas about what goes on inside a black hole? Is it a crowd of cats, like Lindsay and Marshall envisioned? Or something completely different? Email us here!