4 ms·
"do fusion efficiently locally" - with what? The vast majority of available fuel is in the stars. Dyson spheres are different than planet size civilization. For
by empiricus 5y ago
"do fusion efficiently locally" - with what? The vast majority of available fuel is in the stars.
Dyson spheres are different than planet size civilization. For planet size civilization, with population in the order of billions/trillions ppl, local fusion is probably good enough. But for populations a billion times bigger, so billions of billions of ppl, you need dyson spheres, or alternatively, a way to destroy stars and get the raw hydrogen - probably harder to do.
- ncmncm 5y agoHint: Jupiter is made mostly out of hydrogen. Saturn too. Uranus and Neptune, if those get used up. Also plenty of helium, maybe even more useful. Also: the Pacific, Atlantic, Indian, and Arctic oceans are made of water, which has hydrogen in it. Also all of the Antarctic and Greenland ice, the Great Lakes, Caspian Sea, Lake Baikal, and Lake Victoria.
- akvadrako 5y agoJupiter is much smaller than the Sun, so it isn't really relevant what it's made of.
- ncmncm 5y agoIt is right there, completely unused, and not too hot to get close to. Most likely you would use up Neptune first, and save Jupiter for later.
- csee 5y agoWhy wouldn't they do fusion locally but also build a Dyson sphere? Doing only the former produces less energy than doing both the former and the latter. The view that they wouldn't do both is premised on the assumption that they won't need or want that much energy, combined with the assumption that the problem of disposing of the waste heat makes the extra energy not worthwhile.
- ncmncm 5y agoBecause building out a Dyson sphere is a hell of a lot of trouble to go to for something you manifestly don't need. "Why buy the loaf when you get free slices?"
- csee 5y agoThe word "need" is misplaced. It's not about need. It's about whether the upside of the additional energy is bigger than the downside of having to build the thing out. You're making an assumption that that upside is too small relative to that downside.
- ncmncm 5y agoYou assume that energy would still be considered a limiting resource. When you have overabundant energy, your choices are driven by other concerns. With plentiful energy, materials are cheap, dismantling moons and minor planets. The actually valuable commodity becomes cold, because high-energy processes produce waste heat that must be radiated away, so you move out to the Kuiper belt.