The Kepler satellite, tasked with the meticulous examination of thousands of stars to detect the minute dips in intensity which are caused by the transits of their planets, has detected something odd about the light curve of KIC 8462852. (It’s customary in popular journalistic accounts of this sort of thing to make a sarcastic crack at the fact that the star is known by a catalogue number rather than a name, to which I want to respond, ok, you think up names for the 2.5 million or so stars now known to science, if you’re so smart.) The objects orbiting KIC 8462852 are more numerous than is expected of planets, but inconsistent with the star’s observed age: young stars are surrounded by swarms of dust and rubble, but this star’s spectrum indicates that it’s mature. The objects might be debris from a planetary collision which we are just lucky enough to observe before all the fragments have dispersed, or they might be a large family of comets – the hypothesis favoured by the scientists who, with the help of amateur observers, brought the phenomenon to the press’s attention. But the idea that’s got the article retweeted is far more engaging: alien megastructures.
In a fictional setting, I like a megastructure as much as the next guy: the Death Star, the Other, Larger, Death Star, that big cloud or whatever in the Star Trek film that started out as a space probe. Not to mention the even more grandiose offerings of science fiction novels: Larry Niven’s Ringworld and its descendants in Iain M Banks’ Culture novels, Arthur C Clarke’s Rama, down to the drastic reconfigurations of the Solar System undertaken in Charles Stross’ Accelerando and Hannu Rajaniemi’s Quantum Thief trilogy.
Megastructures, however, straddle that strange territory between science fiction and, if not exactly science fact, then at least science I’ve-got-tenure-so-let’s-see-how-big-these-brain-farts-can-get. The theoretical musings of physicists such as Freeman Dyson, whose eponymous Sphere is a shell constructed in order to capture the entire energy output of a star. Or the Anderson Disk: a circular plate the size of the orbit of Mars, with a hole conveniently placed in the centre in which a sun suffers the indignity of bobbing up and down to provide a day-night cycle. The epitome of this mindset is the Kardashev Scale, formulated by a Russian astronomer in 1964, which rates civilisations on their ability to marshal the energy output of their entire planet (I), their star (II) and their home galaxy (III).
This mode of speculative cosmic architecture is usually recounted with a poker-faced seriousness which goes beyond the fun of science fiction into something stranger and more touching: a deep and unrequited nostalgia for that Heroic Age of Insane Infrastructure, the twentieth century. In a world where both sides of the Cold War contemplated using fission bombs as the world’s least environmentally-friendly earthmoving technology, reprocessing the planet Mercury as the raw material for a sun cosy is just the logical next step. It’s also a displacement of the colonial engineer’s ambitions, thwarted by environmentalism on this world, set free to rend asunder the rest of the Solar System without restraint.
Leaving aside the fact that no known or even hypothetical material has the strength to throw hoops around stars or build artificial moons, none of the scientists, and very few of the science-fiction writers, ever address the social or economic transformations which would be needed to organise any of this. The further we get from the fever of the Cold War, the more the prospect of industrial societies organising any project larger than a cluster of skyscrapers seems to dwindle; on a planet where the nation with the largest economy seems to be forgetting how to maintain its road bridges, it’s hard to imagine, even if we were given the technology and an unlimited budget, how we could sustain the focussed attention required to build even a modest space elevator before we got bored and switched over to Netflix.
Which is why, of course, megastructures are almost always built by aliens (or, in the admirable works of Finnish sf author Hannu Rajaniemi, a particularly brutal and industrious clade of post-humans). Tatlin’s Monument to the Third International stands as the minatory architectural ghost of utopian communism, and it could be that the space-entrepreneurial plans of Elon Musk and Richard Branson will serve future generations as a virtual memorial of capitalism. But aliens—who, like robots, are a sort of dumping-ground of wistful but incorrect ideas about our own capacities—never faced these disappointments; their Tatlin’s Towers reach all the way to the stars.
In fiction, megastructures are usually abandoned, enigmatic and perilous, and when we read pop-sci articles which treat them as a serious possibility, we should remember their true nature as aesthetic objects: the grandest incarnation of the statue of Ozymandias that our culture has yet produced. In his novel The Pastel City, M John Harrison wrote of the empires that preceded his beautiful and melancholy city of Viriconium:
The last of them left its name written in the stars, but noone who came later could read it.