Is practical fusion power an example of "unpredictability" (certainly yes) or of "clearly understood to be worth developing" (I'd say no). Fusion reactors have typically been proposed as a way to reduce the fuel-cost of boiling water, relative to fission reactors, while multiplying the capital cost by an unknown and probably huge factor. Why all the excitement?

By contrast, technologies that are, in some sense, about reducing their own costs are in a different and unusual category. (Someone should look into this, and not just the usual specially-interested experts.)


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