Don't remember the name, but I read a very similar story. It takes place on a Dyson sphere surrounding not Sun, but a star 10 ly away (Epsilon Eridani?), which started out as a human colony. The humans had forgotten their origin and lost most of their technology. They live on the inside of Dyson sphere, roofed over with something transparent. Quite correctly, gravitational acceleration is tiny and directed "up", toward the sun. People live in essentially free-fall, but loose objects accumulate on the "ceiling".

Cute touch: they know what a planet is, and some theorize they must have originated on a planet. One of the arguments brought by the opponents of this view are chickens -- chickens clearly are designed to fly and do, yet could never fly in the gravity of a planet capable of retaining its atmosphere. Ergo, chickens could not have originated on a planet.

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