Matrioshka Brain Simplified

"Take all the planets in a star system and dismantle them," she explains. "Turn them into dust – structured nanocomp, powered by heat exchangers, spread in concentric orbits around the central star. The inner orbitals run close to the melting point of iron, the outer ones are cold as liquid nitrogen, and each layer runs off the waste heat of the next shell in. It's like a Russian doll made out of Dyson spheres, shell enclosing shell enclosing shell, but it's not designed to support human li...

 Two Factions of the Model Railroad Club

There were two factions of TMRC. Some members loved the idea of spending their time building and painting replicas of certain trains with historical and emotional value, or creating realistic scenery for the layout. This was the knife-and-paintbrush contingent, and it subscribed to railroad magazines and booked the club for trips on aging train lines. The other faction centered on the Signals and Power Subcommittee of the club, and it cared far more about what went on under the layout. This w...