[mkl]

A picky correction: the Culture has both Orbitals and Rings, and defines them differently, but you're treating them as one. Quoting myself from a year ago [1]:

> Orbitals, while enormous (greater surface area than earth), are much smaller. The Culture novels do have Ringworld-sized rings as well, though. E.g. from Consider Phlebas, flying under the orbital Vavatch: "It was like flying upside-down over a planet made of metal; and of all the sights the galaxy held which were the result of conscious effort, it was one bested for what the Culture would call gawp value only by a big Ring, or a Sphere."

[1] https://news.ycombinator.com/item?id=22144228

[QuesnayJr]

I thought Orbitals were Dyson spheres. What are they?

[mkl]

They are Rings but smaller. Culture Rings are like Niven's Ringworld, and go all the way around a star, spinning around the star to simulate gravity. Culture orbitals are also ring-shaped and spinning to simulate gravity, but they're nowhere near as big (relatively speaking; still more surface area than Earth), and generally orbit a star more like a planet does. Culture Spheres are Dyson spheres.

[arethuza]

The size of an Orbital is dictated by day length and surface "gravity" - they are arguably more elegant than Niven style Rings which need a lot of extra stuff to generate day/night cycles (shadow squares?).

[mkl]

Yes. One book (The Player of Games?) gave enough numbers for me to do the calculations, and it matched about 24h and 1g.

[simonh]

I don't think the Culture builds rings or spheres themselves, but they exist and they are aware of them. There are civilizations in the galaxy considerably more advanced than the Culture.

[dodobirdlord]

I believe the Culture is credited as having creating the ring in Consider Phlebas.

[mkl]

Do you mean Vavatch, that was scheduled for destruction? That was Culture, but an Orbital.

[arethuza]

Vavatch was destroyed by a militarised Culture GSV but it wasn't "owned" by the Culture.

[wiml]

Banks' "Orbitals" are smaller rings, perhaps planet-diameter, orbiting at a distance from their star; "Rings" are Niven-Ringworld-style structures with a star in the middle. Spheres are mentioned here and there, I think, just called "spheres".

[kurtschiller]

Good catch, thank you!