5 ms·
It's astable, not unstable. The net gravitational force from the contained star is roughly zero for any positioning of the Dyson sphere. Therefore, it can drift
by wyager 9y ago
It's astable, not unstable. The net gravitational force from the contained star is roughly zero for any positioning of the Dyson sphere. Therefore, it can drift away from perfectly centered, but there's no runaway instability. You can correct its position very cheaply by e.g. modulating the transparency of different sections of the sphere and using light pressure to keep it centered. Obviously there are other concerns, but positional instability isn't that bad, relatively speaking.
- taneq 9y agoActually, wouldn't light pressure automatically keep it centered (assuming it's consistent enough and therefore the net gravitational force is close enough to zero)?
- wyager 9y agoI'm not sure... I think it might cancel perfectly. I'd have to do the integral to make sure, but at least conceptually if you bisect the sun in half in any diresction, the net momentum flux is equal in both directions. That's only if the interior of the sphere is dark; I don't know how elastic reflections would figure in to this.
- Filligree 9y agoReflections make everything harder, but I think you're right. The situation seems isomorphic to the calculations that prove it's gravitationally astable.
- taneq 9y agoHmm. I think you're right - the fact that it's a closed surface means you can discard all that inverse-squared-law stuff and just go with conservation of momentum. Darn.