[wavesum]

I think the biggest fallacy in this rationalization is when it is assumed that advanced civilizations would want to expand like yeast; consuming everything, building dyson spheres... Why would they want that much energy, and why extract it from the sun? Trying to picture myself as one of these superlifeforms, I think would like to have the sun visible... For sunbathing and sh... plants to grow etc... Maybe they have built little fusion reactors wherever they need energy?

[fernly]

The SUN is visible everywhere within a Dyson sphere; it's the STARS that you can't see any more. The idea isn't that a civilization wants to do this; the idea is that it needs that much energy to continue with whatever industrial or infrastructure processes it requires to support a very large population. Dyson reasoned, we need steadily increasing amounts of energy input to support what we are doing; if the trend continues, what's the limit? (Typical physicist question, no?) The limit is to harvest all the energy emitted from your star. The only way to do that is to build a spherical collector, so that every photon can be captured. Then where do you live? On the sphere's inner surface. Of what material could you build a stable sphere one AU in radius? Where would that bulk of material come from and how be processed and positioned? How would you provide gravity on its inner surface? We have no fucking idea -- but we are not a Type-whatever civilization.

[JoeAltmaier]

I always thought that was a primitive notion. We can build the sphere, but not control the star? Imagine a caveman - "Limit to civilization when all energy from campfire captured - most people warm, most meat cooked" Clearly one can do better than a campfire.

Instead, imagine harvesting energy from the star asymmetrically - from flares or from the inside out. Or get your energy from a neighboring star. Or make your own star. Or whatever a Type-whatever civilization decides to do.

[sooheon]

I agree. Why the assumption the Type 3 capable civilisations will necessarily wish to metastasise across the entire universe? One would hope that civilisations' ideas of what constitutes fulfilling and worthwhile activity will evolve and improve along with their technology.