[PTTG]

SimonAce I think you're stretching to make a science miracle seem improbable. Given the effectiveness of the fusion posited by Astromancer, it's probably He3 fusion, or maybe something weird like Deuterium-Li6.

These all have in common very high input energy levels, but a single change could make this all much easier. Perhaps an ultra-high-temperature superconductor is invented -- one that can be produced in reasonable quantities fairly cheaply. Perhaps 500 times the cost of copper wiring.

Depending on the operating limits of that material, it could increase the strength of needed magnetic fields a hundred times or so, making even weirder fusion types both possible and cheap. Or maybe a neural network comes up with a completely unexpected shape for a fusion bottle that allows similarly high magnetic flux using conventional materials.

In either case, old economic models no longer apply. Pumping out fusors would be a hyper-profitable business, and they could iterate at the speed cell phones did in the first decade of the millennium.

Of course, the knock-on effects of the exact scientific miracle would vary. Superconductors that work at plasma temperatures would be useful for a lot of other things, as would neural networks able to handle magnetohydrodynamics better than humans. But they would also probably be less obvious than free omnipresent power.