Exploring Black Holes: Frozen Stars and Gravitational Dynamos

Black holes are gravitational superheroes. Here is their origin story, including World War I, magnificent mustaches, and Albert Einstein.

Part 1 of a four-part series on black holes. This part defines what a black hole is, goes back to the beginnings of black hole research, and shows how physicists came to terms with the existence of these weird objects. Part 2 will talk about the role black holes play in galaxies and how invisible objects can become some of the brightest things in the cosmos. Part 3 will explain how astronomers observe black holes using the most sophisticated observatories around. Part 4 will get into the weird side of black hole science: how these objects challenge our fundamental theories of physics.

February 11, 2016, was a landmark day. After many decades of searching, scientists announced they had detected gravitational waves for the first time: disturbances in the structure of space-time that travel at light speed. But there was a second triumph of physics hiding inside that one. The waves gave us the best evidence so far for the existence of some of the most fascinating objects in our universe: black holes.

Few scientists these days doubt that black holes exist. But in a way, all our evidence for them is circumstantial. Black holes, by their very nature, are difficult to observe. All light falling on them is absorbed, rendering them nearly…