Imagine a world one AU in radiusthat's 93 million milesand 186 million miles in diameter, with a circumference of 584,336,233.568 miles. Since this world is hollow, with a G-class sun at its center, it has an estimated volume of 1.08617 miles (I don't think there's a word for a number that big). Its surface isn't solid, though, but instead is comprised of approximately six trillion open-center hexagons, each having a perimeter of 6,000 miles. Every hexagon has six cylindrical habitats 1,000 miles long and 100 miles wide. Most, if not all, of these "biopods" are inhabited by one alien race or another, and no one knows for sure how many live here… except perhaps the danui, the ones who built this place, and they're not telling.
I've been fascinated by Dyson spheres ever since I read Bob Shaw's Orbitsville, the first novel to deal with Freeman Dyson's concept (yes, I know all about Larry Niven's Ringworld… but that isn't a sphere, is it?). Since then, I've read or seen other treatments of the same ideanotably the shellworlds of Iain Banks's Culture novels, and "Relics", one of the better episodes of Star Trek: The Next Generationand have generally enjoyed them all.
Nonetheless, a number of things have always bugged me. Looked at from a practical point of view, Dyson spheres don't seem to make a lot of sense. Build a solid sphere around a star, and you'll inevitably run into a couple of big problems: namely, a runaway greenhouse effect will eventually make the place uninhabitable, which will probably occur shortly before trapped heat causes the shell to overheat, expand, and fracture just a sidewalk in summertime.
And even if you ignore all that, there's also the question of purpose: why build something this enormous if it can have only one kind or environment? Orbitsville, for example, has a nitrogen-oxygen atmosphere, an everlasting summer, and endless plains of grass. Not only is that… well, rather boring, if you ask me; I like winter, and I love cross-country skiing… but it's also a waste of potential; thousands of different, non-human races could comfortably reside in something like this, if only there were more environmental variation.
I'd been muddling this stuff around the time I finished Coyote Destiny, the fifth and last book of the Coyote series. This was the conclusion of an epic I'd been writing during the last ten years; during the same time, I'd also done two novels set in the same universe, Spindrift and Galaxy Blues, which formed a parallel storyline to the events taking place on Coyote. Now that the Coyote series was complete, I wanted to provide a capstone for the spinoff novels as well. And since this would probably be my last hurrah, I wanted to go out with something big.
Which brought me back to Dyson spheres and all the questions I had about them. Freeman Dyson is a very smart man; I could not believe that one of the leading physicists of our time would devise something which had such obvious flaws. So I visited the University of Massachusetts science library, tracked down the issues of Science from 1960 in which Dr. Dyson published a couple of letters explaining his idea, and got a surprise: the Dyson spheres of science fiction bear little resemblance to his original concept.
Dr. Dyson had suggested that these spheres would be individual habitats orbiting a star, rather than a solid shell with a sun at its center. In fact, he owed his inspiration to J.D. Bernal's The World, The Flesh, and the Devil, published in 1929, which discussed the possibility of something rather similar. All right, this made sense… except that, with zillions of these habitats spinning around a star, you'd have one mother of a traffic-control problem. And not only that, but wouldn't it make sense to connect them somehow, so that inhabitants could easily travel from habitat to another?
I was thinking about this when I stumbled upon a web site article about the properties of fullerenes, sometimes also known as buckyballs. The article featured a diagram of a carbon-based fullerene… but to my mind's eye, it was a Dyson sphere, only with a framework of six-sided habitats around a central point.
So my Dyson sphere would be something like that: a vast assembly of hexagons, each one sharing sides its neighbors, constructed in orbit around a star. An afternoon spent doing the math for the dimensions of such an object producing bowel-loosening results. Don't ask what the mass of this thing would be; a fan tried to figure it out when I described Hex to him, and threw down his pen in frustration.
Once I drew pencil sketches of Hex, my friend Rob Caswell came up with the frontispiece illustrations that appear in the book. Rob also read the book as I was writing it and made several suggestions. And I had great fun coming up with the different aliens that appear during the novel; some, like the hjadd, had previously shown up in Spindrift, Galaxy Blues, and the Coyote novels, but others like the danui and the soranta haven't been seen before.
Figuring out why someone would go to the trouble of building something like this provided me with much of the plot and story. I won't go into that here, except to say that Hex isn't a Big Dumb Object; it's a Big Smart Object, its creators haven't disappeared, and their motives are eventually explained. You'll have to read the book to learn more.
Hex is about the discovery and exploration of Hex. But despite what I said at the beginning of this essay about this novel being a series finale, I'm not entirely certain that I'm done with this place. I've got some questions of my own that I'd like to have answered.