Robert Bradbury the person who introduced us to Matrioshka Brains has passed away. Here's an eloquent memorium from George Dvorsky. I wonder if we will ever learn that there are billions of Matrioshka Brains in the Milky Way, most of them far from the galactic center. We currently call them dark matter.

If I had my choice of where to live in the Milky Way I would want to be as far as possible from the monster black hole at its center.