m. c. de marco: To invent new life and new civilizations...

Today’s Big Dumb Object (BDO) is a Hoopworld or toroidal planet shaped like a doughnut. While it’s possible that such planets might form natually, they would be unstable over the long term. Anders Sandberg evaluates a couple of possible toroidal planets of “natural” size (whether natural or artificially constructed)—that is, up to about six times the surface area of the Earth.

One disadvantage of the natural size is that the day length on a toroidal planet is only a few hours. Orion’s Arm postulates a less natural hoopworld with a more natural day length: about 90,000 miles across, and about an Earth-sized diameter in cross-section.

To make larger hoopworlds like that, you need some artificial BDO construction and maintenance methods. In Episode 7 of Isaac Arthur’s Megastructures video series, he discusses exotic construction methods for hoopworlds and suggests linking your hoopworlds together into a chain around a sun (just because you can) or putting a topopolis or more hoopworlds in the middle of it.