Alien megastructures: we shouldn't search for ourselves in the stars

I spoke recently at a scientific gathering about a theory suggesting that life, far from being very rare in the cosmos, might be expected to spring up wherever planetary circumstances permit. Afterwards, an eminent cosmologist asserted that this idea couldn’t be right, because then intelligent civilisations would have spread throughout the universe and we’d be surrounded by neighbours—who would surely have made themselves known by now. He was invoking the Fermi Paradox. The Italian physicist Enrico Fermi once responded to a conversation about extraterrestrial beings by saying that if they exist then “where is everybody?”

My reply was to wonder how the cosmologist knew so much about the motives and behaviour of beings far more advanced than us. The Fermi Paradox makes the same assumption as just about all discussions of “alien civilisations:” that they’re really a lot like our modern industrial societies, only with blue skin, bald heads, pointy ears—and really cool tech.

And of course, why would we think otherwise, given that pretty much all the images we have from science fiction follow this template? Still it puzzles me that those images are tacitly accepted without question whenever scientists talk about alien intelligence and civilizations. Those extraterrestrials might come in peace, or they might come in war (because that’s what we do, right?)—but rest assured, they’ll come if they can (because that’s what we do too.) How could they not? Isn’t colonisation just an expression of the Darwinian survival instinct, which must underpin life everywhere?

But a moment’s thought shows what a lack of imagination is involved here. We have not the faintest idea what an “intelligent” species other than our own would think like: what their self-image would be, what sense of obligations or imperatives, what concepts they would use to frame the world. Even the notions that shaped the worldview of our own species a thousand years ago, or of more recent pre-industrial cultures, are in many ways unrecognizable to the citizens of today’s technological societies. I feel confident that the actions, technologies and motives of humans a millennium in the future would be all but incomprehensible to us, and nothing like anyone now envisages. Were we to encounter them, the “Huh?” factor of the final scenes of Kubrick’s 2001: A Space Odyssey would be nothing in comparison.

All this might colour our response to a recent story that astronomers have found a star between the constellations of Cygnus and Lyrae in our galaxy with light-emission features that seem very hard to explain on the basis of existing models of solar systems. The astronomers suggest these just might be explained as the signature of some super-advanced technological reworking of the entire circumstellar region.

The star can’t be seen with the naked eye, but was spotted by NASA’s Kepler Space Telescope, an orbiting instrument designed to look for stars whose light output carries the signatures of a surrounding planetary system. The new star, called KIC8462852, bears the imprint of something around it that is altering its light flux: it dips irregularly over the course of many days, sometimes by as much as four-fifths, before returning to its normal level. This is certainly very odd. The emission looks like what you might expect if irregular, large orbiting clumps of dust and matter were sometimes occluding the star. But one would expect that only in the early days of a star’s life, while its solar system is still forming. Yet KIC8462852 seems to be a mature star and should be past all this. So what is this stuff?

No one is actually claiming to have found the fingerprint of an alien civilization—that suggestion is really little more than a matter of having fun with a puzzling discovery. The international team of researchers seems to favour an unusual but plausible explanation in which KIC8462852 captured comets from another passing star. But some of the team think that a more exotic scenario is also worth considering, and are working with scientists at the SETI (Search for Extra-Terrestrial Intelligence) Research Center at the University of California at Berkeley to get time on radio telescopes to probe KIC8462852 further, looking for radio emissions that one might expect from an advanced technological culture.

The researchers admit that alien technologies are something of a last-resort hypothesis for explaining KIC8462852’s odd output. The idea here is that the strange dips in the light flux might be caused by gigantic space structures, perhaps created to harvest starlight—like the solar arrays that some engineers have proposed for our own planetary environment.

In the 1960s, the physicist Freeman Dyson proposed that advanced civilisations would create something of this kind, producing an engineered solar system that became known (to Dyson’s chagrin) as a "Dyson sphere." He reasoned that Alien societies will eventually feed their energy demand by harnessing more and more of the heat and light from their sun, surrounding it with an increasingly solid megastructure made from a swarm of light-harvesting and perhaps inhabited objects. Eventually this would transform the characteristics of the starlight seen from afar, and could even end up capturing the entire stellar output of energy.

Dyson’s idea was partly inspired by science fiction: a structure like this was described in Olaf Stapledon’s 1937 novel Star Maker. A culture capable of making such a thing would have reached the second stage of the technology-based classification of advanced civilizations proposed in 1964 by the Soviet astronomer Nikolai Kardashev. We are currently on the first rung of this scale in terms of the energy we have at our command; a civilization that progressed to harness energy not on a stellar but on a galactic scale qualifies as stage 3.

This is all good fun. But it is evidently the result of asking the question “what would I do, if I had the technical capability?”—which is unlikely to be the right question. One might say that, in order to talk about alien civilizations at all, we have to start somewhere, and this is the only place we’ve got. That’s very true. But we should bear in mind that it’s hard to spin science out of ignorance, no matter how learned the effort. When the starting point is us, this kind of speculation is sure to end up doing precisely what most good science fiction does: not predicting the future, but revealing the preoccupations of the present.