Dyson Spheres: Fiction or Fantasy? (definitely not vacuums)

I don’t mean to just flat-out say that Dyson Spheres are impossible (even though they are). Instead, I separate their possibility into two categories: “fiction” and “fantasy.” Here,  fantasy is something thought up by the imaginative yet impossible (think wizards and dragons) but fiction is something thought up that *could* be real. Maybe.

In 1960, Dyson wrote an article (letter?) to Science, stating a fun mind experiment that he had come up with: that advanced civilizations could build a “biosphere” (later called a Dyson sphere) around their star out of some outside matter (e.g. Jupiter), successfully harnessing all of the power of the star and solving over-population problems. This biosphere would block radiation from the star to outside viewers, except in the IR. Therefore, Dyson argued, we should begin a search for objects with strong IR emission and not much else.

It’s hard to discuss this paper without mentioning some of the published responses he received and his rebuttal to them, mostly because some other people basically mentioned my arguments to this idea nearly 58 years ago. Maddox points out that a Dyson sphere is physically impossible. To keep this shell in orbit around the Sun at any distance in the Habitable Zone would require some force counteracting gravity and pushing outwards on the sphere. In stars, this is radiation pressure. Maddox points out that radiation pressure wouldn’t really work, but doesn’t go into any specifics beyond that (it was only a short response). I wonder if there is any material strong enough that we know of or even theorize that would maintain its structure, so that the rigidity itself was counteracting gravity. Probably not, but still fun to think about. Dyson counters that by biosphere he imagined was obviously not whole as that would be impossible, but instead made of “a loose collection or swarm of objects traveling independent orbits around the star.” Wait, what? So even though it is a sphere, it’s not actually a sphere. But it is a lot of artificial bodies around the star..would that be bodies going the same velocity so having the same semi-major axis? Or are people just going to build a bunch of planets with different inclinations to fully cover a sphere? I can understand what s sphere around a star would look like, and agree that it probably is not mechanically possible, but I cannot figure out how “a loose collection or swarm of objects” would work at all. Personally, I feel this clarification terribly backfired. I had also always thought of and heard of Dyson spheres as being, well, spheres, so it seems that this clarification wasn’t read or remembered by most anyways.

Anderson then argues that such a sphere could not even be constructed. Since it would take so long to construct (several thousand years), there is basically no way that a civilization would bother continuing it. Sure, they could start, but after a few generations someone would come up with a better solution to over-population or for energy usage that would require so much less work and time. He argues that the only way this could work would be to go all Brave New World and condition people to accept the continuation of the project, in which case people could just be conditioned reproduce at sustainable rates! I completely agree with this argument, although I’m not sure how relevant it is to Dyson’s paper. It is true that a Dyson sphere is so unlikely to be produced that no civilization would do it, but Dyson spheres themselves aren’t really possible, so this seems like a waste of ink. I, however, do not agree with Anderson’s conclusion that “astronomical discovery of infrared sources won’t prove anything about the inhabitants of other planets.” I mostly don’t agree with this because we have no way of knowing for sure what we can learn from an IR signature until we actually start looking at them. Only slightly related to this, we can *detect* planets using their IR signatures (kind of, direct imaging in the IR is easier due to the slightly less horrible contrast issues); besides, as Maddox pointed out, an IR search would still be astronomically valuable, even if it wouldn’t lead to the discovery of Dyson spheres.

I personally believe that Dyson spheres under the definition of a solid sphere somehow encasing a star are impossible. The sheer force required to keep the sphere together would be insane, and no civilization would bother putting that much time and money into such a feet (we can’t even get funding to put man back on the Moon!). I can see the appeal of a Dyson sphere as it would lead to plenty of space for people and solar panels and such, but I don’t think it would solve over-population problems nor do I think anyone would bother making it.