A Few Notes On The Culture, by Iain M. Banks

From the notes:

Of course, the materials used in the construction of something ten million kilometers in circumference spinning once every 24 hours are far beyond anything we can realistically imagine now, and it is quite possible that the physical constraints imposed by the strength of atomic bonds ensure that such structures will prove impossible to construct, but if it is possible to build on a such a scale and subject such structures to forces of these magnitudes, then I'd submit that there is an elegance in using the same rotation to produce both an acceptable day-night cycle and an apparent gravity which makes the idea intrinsically attractive.

I've been thinking off and on about materials needed to construct an orbital. [1]

To construct an entire ring (as opposed to just two opposing plates held in place by tractor beams), I believe that nothing more exotic than regular steel would be required. Solid mountains of stone might be a challenge, but making them hollow is feasible. And having oceans with an average depth of 4km should be readily achievable too.

If, for example, a 100m thick steel ring is not sufficient to construct an orbital, I'd like to hear otherwise.

[1] http://www.reddit.com/r/TheCulture/comments/11mt3m/speculati...