A commenter on a discussion of femtotech at HPlus gave a detailed breakdown of how to feed 30 billion people on Planet Earth and squeeze them in…
Work Free Future / There’s Still Room on Earth – BUT SHARE
…was kind of a non-sequitur in the context. Here’s my reply…
Nice, though kind of unrelated. And you’re missing the point. All those foodstuffs could be manufactured via nanotech food-fabbers from basic CHON materials (plus essential micronutrients) from any source. If you want a world fed and powered by solar, then we can do much better than the ~0.1% energy storage efficiency of living things. Every person on Earth could be fed and serviced from an associated tank of raw-materials feeding into the right nano-tech system. We might need to get used to the idea of throwing our things back in the fabber to be reconfigured, but I am sure we could adapt.
In that situation, then how many can be accomodated on Planet Earth? Personally, given the prospect of bulk carbonoid materials of near diamond strength materials, I like Arthur C. Clarke’s concept from his “3001: The Final Odyssey” of the large inhabited towers reaching up to geosynchronous orbit. Assuming 3.5786 metres per level, then each tower is 10,000,000 levels high. Assuming a lateral cross-sectional area of ~ 1 km^2, then 3 towers arranged equidistant around the equator represent 30,000,000 sq.kilometres of accomodation. Giving each person a generous 1,000 square metre allotment, then allows the 30 billion previously proposed to be accomodated with minimal use of terrestrial landscape. Of course a wider set of Towers can squeeze more in. 300 billion? 3 trillion?
How much energy do they need? Connected to geosynchronous orbit directly the Towers might be powered entirely from the bounty of the Sun directly. Supporting 3 trillion at the 10 kW/person level – the energy equivalent of 100 times a person’s recommended caloric intake – means 30,000 TW is required. While this is a full quarter of the light absorbed by Earth the collector arrays need only be ~8.4% the area at 50% efficiency due to the near perpetual sunlight at that great remove from Earth’s shadow.
Of course since most people would then be living in space and reduced gravity, the next logical move is further out. Really thinking nano – and human engineering – we might adapt our bodies to empty space itself, recycling most of the time and powering our bodies with the sun. We’d need to work-out how to survive flares (x-ray photosynthetic symbiotes?) and high energy particles, but with nano…
Linda Nagata‘s “Vast” features a variety of different space-adapted humans and aliens, quite convincingly portrayed.