Geology of a supermassive Dyson sphere

There was a question on here a while ago about lighting a massive Dyson sphere, that has gotten me to thinking.

Obviously, such an item needs some unobtainium to build, but ignore that. I'm figuring an inner shell of something like 1 AU across, that is totally empty, on top of this is a layer of rocky-planet type material sufficient to produce 1 g at the surface.

While such a world lacks a "core" and will not possess a magnetic field, the escape velocity is high enough that it should retain an atmosphere anyway (the problem will actually be the opposite of normal - its going to trap some of the wind of its illuminating suns, the hydrogen will react with local oxygen and you'll slowly convert atmospheric oxygen to water). It will have the radioactive materials to produce a heated layer outside the shell, though.

What I'm wondering about is plate tectonics. Do we have a geologically alive world that over time refreshes its surface, or will it simply erode down to flatland? And if the latter, is there any fix?

posted over 8 years ago

Loren Pechtel‭

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