> None of those things are necessary for civilisation That's only true for low values of civilization. Even bronze age tech consumes more than hunter-gatherers

> None of those things are necessary for civilisation That's only true for low values of civilization. Even bronze age tech consumes more than hunter-gatherers which consume more than monkeys. > Besides, surely it must be simpler to build a fusion reactor on earth than harvesting enough material to cover the sun in solar panels. Dyson swarms sit higher on the kardashev scale than harvesting whatever you can get on a single planet. At some point waste heat rather than fuel will also become a real problem. Fusion reactors are ultimately thermal power stations, glorified steam engines. > Would the solar system even have enough resources for that? You'd start small with asteroids. And then disassemble some moons with shallow gravity wells. Which of course again requires stupendous amounts of energy just to move the material around but the sun still has billions of years left so there will be time to recoup that investment.