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

Today’s Big Dumb Object (BDO) is an Alderson Disk, a finite plane with a sun in a hole at its center. The invention of Dan Alderson, it was popularized in Larry Niven’s classic megastructures essay, where he also mentions bobbing the sun up and down to replace the perpetual twilight with actual night and day, and the necessity of a wall to retain the atmosphere at the inner edge.