Black holes are absolutely silent, as they are creatures of pure gravity. But while black holes produce no sound of their own, they can generate sound waves in their environment.
Black holes are surprisingly simple objects. In the general theory of relativity, which is the framework we use to understand all things gravity, you only need three numbers to completely and totally describe a black hole: its mass, its spin and its charge. Seriously, that’s it. If you encounter any random black hole in the universe and measure its mass, how fast its spinning, and how much electric charge it has, you’re done. That’s all you’ll ever learn about the black hole, and all you’ll ever need to understand how the black hole will behave.
Now, our journey towards a complete understanding of gravity is not yet done. We know that general relativity is incomplete, as it predicts that the ...
