Hacker News Reader

Comment by ncmncm | Hacker News Reader

Any crow, dolphin, or half-wit would have predicted US failure in Afghanistan. Donald Rumsfeld was Secretary of the US DoD at the time of the invasion. There is no public evidence that he predicted failure.

Freeman Dyson never proposed building anything even vaguely like what is called a Dyson Sphere, and was famously irritated at having it attributed to him.

View on HN

> Dyson had also proposed that the search for extraterrestrial intelligence (SETI) programs should “search for sources of infrared radiation” to “accompany the recently initiated search for interstellar radio communications.”

https://www.inverse.com/science/how-many-dyson-spheres-are-i...

I remember some discussion of this point in his autobiography. He wasn't talking about the Star Trek version, but certainly the intercept-all-the-sunlight constructions we're talking about.

Anyway, intercept-much-of-the-sunlight. It would be seriously impractical to arrange to intercept radiation leaving a star at high latitudes. And, being made of trillions of independently-orbiting tree-like things, there would be as many small gaps where native starlight would squeak out.

Not mere trillions, on the order of 10²¹ if we're talking about trees similar in size to existing trees. The latitude is irrelevant, because the rotation of the star has an insignificant effect on the orbits of objects at distances hundreds of times its radius. Yes, there would be many small gaps. That doesn't significantly affect the utility of the artifact.

All of this is obvious to anyone who does the math.

There is no reason to assume that trees in a weightless environment would be limited to sizes seen under 1G acceleration. Metabolism would need to be very different, too, because evaporation is not available to drive transport.

Obviously the rotation of the star has no effect. But the need to move between habitats precludes substantial differences in orbital plane (look up orbital plane maneuver, these take exceptionally large delta-V), keeping things close to the ecliptic.

Doing the math produces a picture very different from what you imagine.

If Alice is going from Arcadia Habitat to Zenith Observatory, and Bob is going the other way, and they're of equal mass, it's a momentum exchange. In a developed solar system the transport network could make a lot of hay out of this principle.

Even if the cities do cluster in one plane, that doesn't imply the power stations will.

I think you're wasting your time; cf. https://news.ycombinator.com/item?id=30408971

Probably. And I probably just wasted more time on another thread from a week ago. Going to take tomorrow off from HN.

Wasting my time, anyway.

Unavoidable until you make the effort to level up a bit, but at least we can avoid wasting the time of more advanced people.

Power stations? You mean trees?

Yeah, I considered getting into that, but it was late and it didn't feel that important.

Probably if you believe that dolphins and crows understand human politics and battlefield tactics, and you believe trivially falsifiable things about Freeman Dyson (https://en.wikipedia.org/wiki/Freeman_Dyson#Dyson_sphere), there is not yet any point in talking to you about subjects like this. Maybe in five years.

I'm glad you liked Energia though.

Reply on news.ycombinator.com