Experience curves, large populations, and the long run

If our civilization avoids catastrophe, will we generally be able to advance technology to close to physical limits, match or exceed observed biological abilities, and colonize the universe? Or will we be stuck in a permanent technological plateau before that, reaching a state where resources are insufficient to make the breakthroughs to acquire resources and continue progress? Experience curves, which forecast cost improvements in technology as a function of cumulative production, are a popular tool for technological forecasting and perform relatively well compared to other statistical approaches, although they inevitably have significant and increasing error as one extrapolates further. If we consider the maximum energy resources and population of the Earth, combined with the potential lifetime of human civilization (absent existential catastrophe), experience curves extrapolate to immense technological improvements (constrained by physical limits), more than sufficient to colonize the rest of the solar system, which in turn yields a billionfold increase in potential scale to fund interstellar colonization. Such extrapolation would suggest matching or exceeding biological capacities we currently lack, such as the computational efficiency of brain tissue, or the rapid energy payback of algae as solar energy and manufacturing devices.

Terrestrial solar energy could eventually support extremely large economies and populations

If we are interested in whether Earth's civilization could ever reach various technological milestones, or long run economic output and populations that Earth could sustain, the terrestrial solar energy resource can provide helpful information. Using efficiencies of the best lab solar cells, covering the earth with solar panel platforms could provide a thousand times as much energy as our civilization currently uses, and more than a hundred times the production of the terrestrial biosphere. Historical experience curve and cost data suggest this energy supply could be much cheaper than current energy prices, although with increasing overhead costs as less desirable areas such as ocean platforms and less sunny lands are used. Energy payback times are already under a year for energy-efficient solar in good locations, and have been falling along with prices, so solar energy can power its own construction, and with advanced robotics and AI might eventually grow at extremely rapid rates. 

The High Frontier, space based solar power, and space manufacturing

The High Frontier, published in 1976 by Gerard K O'Neill, lays out a vision of economically profitable space colonization in artificial orbital habitats, and guessed (while disclaiming it as prediction) that it was "unlikely" that a space community would not be established in 30 years. I was interested in why those forecasts were made, and why they turned out wrong, as data points for thinking about forecasting future technological developments. The book lays out a case that in the long run space habitats can support immensely larger populations and wealth than the planets in the Solar System. In the medium term it argued that a government program to invest hundreds of billions of dollars to build space factories and Lunar mining facilities would eventually let them produce solar power a few times more efficiently than terrestrial solar power production, and that this would drive space colonization. This seems to have been doomed for multiple reasons, radically underestimating launch costs and likely fatally underestimating the increased costs of space production (to be paid for out of a 2-3x improvement in solar radiation), as well as requiring immense government funding. As a means to improve solar power cost-effectiveness, it would have been far inferior to solar cell R&D. Subsequent orders-of-magnitude improvement in launch costs per kW of solar cells make space-based solar more plausible than at the time, but the challenge of competing with terrestrial solar and especially terrestrial scale economies of industry remains high.