What are efficient Dyson spheres probably made of?
There are many possible Dyson sphere designs, but they seem to fall into three broad categories: shells, orbital swarms, and bubbles. Solid shells are probably unrealistic. Known materials aren’t strong enough. Orbital swarms are more realistic but suffer from some problems with self-occlusion and possibly collisions between modules. Limitations on available materials might still make this the best option, at least at first.
But efficient Dyson spheres are probably bubbles. Rather than being made of satellites, they’re made of statites, that is, solar sails that don’t orbit, but hover. Since both gravitational acceleration and radiant intensity follow the inverse square law, the same design would function at almost any altitude above the Sun, with some caveats. These could be packed much more closely together than the satellites of orbital swarms while maybe using less material. Eric Drexler proposed 100 nm thick aluminum films with some amount of supporting tensile structure. Something like that could be held open by spinning, even with no material compressive structure. Think about a dancer’s dress being held open while pirouetting and you get the idea.
The radiation needs to be mostly reflected downwards for the sails to hover, but it could still be focused on targets as long as the net forces keep the statites in place. Clever designs could probably approach 100% coverage.
What percent of the solar system can be converted into Dyson-sphere material?
Are gas giants harvestable?
Eventually, almost all of it, but you don’t need to to get full coverage. Yes, they’re harvestable; at the energy scales we’re talking about, even stellar material is harvestable via star lifting. The Sun contains over 99% of the mass of the Solar System.
How long would it take to harvest that material?
I don’t know, but I’ll go with the 31 years and 85 days for an orbital swarm as a reasonable ballpark. Bubbles are a different design and may take even less material, but either way, we’re talking about exponential growth in energy output that can be applied to the construction. At some point the energy matters more than the matter.
What would the radius of a Dyson sphere be? (i.e. how far away from the sun is optimal). How thick?
I’d say as close to the Sun as the materials can withstand (because this takes less material), so probably well within the orbit of Mercury. Too much radiation and the modules would burn up. Station keeping becomes more difficult when you have to deal with variable Solar wind and coronal mass ejections, and these problems are more severe closer in.
The individual statite sails would be very thin. Maybe on the order of 100 nm for the material, although the tensile supports could be much thicker. I don’t know how many sails an optimal statite module would use (maybe just 1). But the configuration required for focus and station keeping probably isn’t perfectly flat, so a minimal bounding box around a module could be much thicker still.
An energy efficient Dyson Sphere probably looks like a Matrioshka brain, with outer layers collecting waste heat from the inner layers. Layers could be much farther apart than the size of individual modules.
If the sphere is (presumably) lots of small modules, how far apart are they?
Statites could theoretically be almost touching, especially with active station keeping, which is probably necessary anyway. What’s going to move them? Solar wind variation? Micrometor collisions? Gravitational interactions with other celestial bodies? Remember, statites work about the same regardless of altitude, so there can be layers with some amount of overlap.
“if an AI is moderately ‘nice’, leaves Earth alone but does end up converting the rest of the solar system into a Dyson sphere, how fucked is Earth?
Very, probably. And we wouldn’t have to wait for the whole (non-Sun) Solar System to be converted before we’re in serious trouble.
There are many possible Dyson sphere designs, but they seem to fall into three broad categories: shells, orbital swarms, and bubbles. Solid shells are probably unrealistic. Known materials aren’t strong enough. Orbital swarms are more realistic but suffer from some problems with self-occlusion and possibly collisions between modules. Limitations on available materials might still make this the best option, at least at first.
But efficient Dyson spheres are probably bubbles. Rather than being made of satellites, they’re made of statites, that is, solar sails that don’t orbit, but hover. Since both gravitational acceleration and radiant intensity follow the inverse square law, the same design would function at almost any altitude above the Sun, with some caveats. These could be packed much more closely together than the satellites of orbital swarms while maybe using less material. Eric Drexler proposed 100 nm thick aluminum films with some amount of supporting tensile structure. Something like that could be held open by spinning, even with no material compressive structure. Think about a dancer’s dress being held open while pirouetting and you get the idea.
The radiation needs to be mostly reflected downwards for the sails to hover, but it could still be focused on targets as long as the net forces keep the statites in place. Clever designs could probably approach 100% coverage.
Eventually, almost all of it, but you don’t need to to get full coverage. Yes, they’re harvestable; at the energy scales we’re talking about, even stellar material is harvestable via star lifting. The Sun contains over 99% of the mass of the Solar System.
I don’t know, but I’ll go with the 31 years and 85 days for an orbital swarm as a reasonable ballpark. Bubbles are a different design and may take even less material, but either way, we’re talking about exponential growth in energy output that can be applied to the construction. At some point the energy matters more than the matter.
I’d say as close to the Sun as the materials can withstand (because this takes less material), so probably well within the orbit of Mercury. Too much radiation and the modules would burn up. Station keeping becomes more difficult when you have to deal with variable Solar wind and coronal mass ejections, and these problems are more severe closer in.
The individual statite sails would be very thin. Maybe on the order of 100 nm for the material, although the tensile supports could be much thicker. I don’t know how many sails an optimal statite module would use (maybe just 1). But the configuration required for focus and station keeping probably isn’t perfectly flat, so a minimal bounding box around a module could be much thicker still.
An energy efficient Dyson Sphere probably looks like a Matrioshka brain, with outer layers collecting waste heat from the inner layers. Layers could be much farther apart than the size of individual modules.
Statites could theoretically be almost touching, especially with active station keeping, which is probably necessary anyway. What’s going to move them? Solar wind variation? Micrometor collisions? Gravitational interactions with other celestial bodies? Remember, statites work about the same regardless of altitude, so there can be layers with some amount of overlap.
Very, probably. And we wouldn’t have to wait for the whole (non-Sun) Solar System to be converted before we’re in serious trouble.