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RE: Could Humanity Ever Really Build a Dyson Sphere?
I think about the resorces we would need to build a Dyson sphere, can our solar system handle that?
I think about the resorces we would need to build a Dyson sphere, can our solar system handle that?
Well, obviously we need to be able to travel to other solarsystems before we can even think of building a Dyson sphere. So we could just mine the resources of barren rocks first and then use those to build it. What I would like to know is how long it would take to build (using future technology ofcourse).
It's not obvious at all that we need so much material. That's just one of those weird cascades of misinformation from people playing telephone with the facts...
Dyson originally did some back of the envelope work to see how thick one could be build at 1.0 AU (not a literal solid shell, but an average thickness of a 'shell' of a vast number of habitats and so on) and came up with 3 meters. Sci-fi authors misinterpreted that and started designing vast impractical spherical habitats sort of like a Bernal Sphere but bigger... This was never supported by credible scientists.
The modern conception from Anders Sandberg and Stuart Armstrong as cited by the video is actually of a very thin one, based on another back of envelope calculation: Mercury's metal content. If you disassembled Mercury and made a sphere from its remains (just the metal part), at 0.3 AU, the average thickness would only be about twice that of household aluminum foil.
Except their paper doesn't say why it would need to be even that thick -- they were actually just wildly overestimating to be conservative. Graphene is only a tiny fraction of that thickness. You would need to layer 1000 sheets of graphene to be heavy enough to not be blown away by the sun's light pressure. Or you could have one layer graphene plus 1000 times as much metal.
The result is called a Dyson bubble... Much lighter, and doesn't orbit (so there is no need for a criss-cross pattern) because it is held up by the light pressure.
Wow , mercury didn't know about that. That's crazy cool. Thanks.
The amount of resources needed has been greatly exaggerated in the media and in popular science fiction. In reality, a 1.0 AU bubble-type sphere would require around the mass of the second largest asteroid, whereas cutting the size down to the orbital distance of Mercury would reduce the cost to a tenth of that. (Really, you'd want to bring the collection surfaces as close to the sun as possible.)
And remember, it's a power collector, not a habitat -- you could beam the energy out to habitats wherever you want throughout more distant space. Smaller spinning containers are much more efficient for producing habitable area, thanks to the square-cube law, and much easier for controlling things like weather.
More likely than putting that all towards landmass production, you'd put the power to work on some scientific project or another. I am a fan of the idea of using it to power vast fleets of computers, and using that to crack hard problems like discovering a cure for cancer.