This is actually not a ridiculous question. Lee Billings, an excellent science writer who specializes in the search-for-aliens beat, had a piece in Scientific American last month in which he speaks to Pennsylvania State University’s Jason Wright, an astronomer who did a novel kind of search. Rather than listen for radio signals from extraterrestrial civilizations, a la SETI, his team instead took the temperature of about 100,000 galaxies to look for evidence of Type 3 civilizations, defined as a civilization that harvests all the energy from all the stars in an entire galaxy.
For perspective, Type 1 on this scale, the Kardashev Scale, is a civilization that has harvested all energy and resources from its home planet, and a Type 2 being one that consumes all the energy from a star. (I think it’s been posited somewhere that the Federation of Star Trek is about a Type 2, the Borg approach Type 3 status, while we contemporary humans live in a Type 0.7 civilization or so.) One guess is that this would be done by use of a “Dyson Sphere,” encapsulating an entire star in some sort of structure that harvests 100 percent of its energy. A Type 3 would do the same thing, but to an entire galaxy.
You think you’d notice something like that going on, right? Right. And they can’t find any.
“On Kardashev’s scale, a type 3 civilization uses energy equal to all the starlight produced by one galaxy,” Wright says. That would equate to an infrared-bright galaxy seemingly bereft of stars. “We looked at the nearest, largest 100,000 galaxies we could find in the [WISE] Wide-field Infrared Survey Explorer] catalogue and we never saw that. One hundred thousand galaxies and not one had that signature. We didn’t find any type 3s in our sample because there aren’t any.”
Even if advanced civilizations do not build Dyson spheres, Wright’s null result also applies to any other energy-intensive “astroengineering” taking place at galactic scales.
I suppose this is somewhat discouraging, but it also isn’t all that surprising. My little brain can barely process even the imaginary idea of a civilization of such scope and power, so the fact that none turned up in a big survey doesn’t shock me. I don’t know if 100,000 galaxies counts as a statistically viable sample of all the galaxies in the universe, but I’d have to guess that if there were any Type 3s out there, they’d be so rare as to elude even such wide nets.
And, frankly, if there’s a civilization that’s powerful enough to eat up a galaxy, and close enough for us to detect it, I’d be a little worried that this civ might get an appetite for a Milky Way.
But Wright says they’re just not there, at all. Fine. But even if he’s right, it only rules out one kind of pan-galactic civ. There may be more than one way to rule a galaxy:
Drawing from Arthur C. Clarke’s famous quip that “Any sufficiently advanced technology is indistinguishable from magic,” in 2011 the science fiction author Karl Schroeder coined an all-too-plausible reason for the apparent absence of aliens: “Any sufficiently advanced technology is indistinguishable from nature.” In this view the future of technology would not consist of star-hopping civilizations spreading like wildfire through galaxies, disassembling planets and smothering suns, but rather of slow-growing cultures becoming more and more integrated with their natural environments, striving for ever-greater efficiencies and coming ever-closer to thermodynamic equilibrium. Simply put, profligate galaxy-spanning empires are unsustainable and therefore we do not see them. “SETI is essentially a search for technological waste products,” Schroeder has written. “Waste heat, waste light, waste electromagnetic signals—we merely have to posit that successful civilizations don’t produce such waste, and the failure of SETI is explained.”
If there’s anything about the idea of things like Dyson Spheres that doesn’t ring true to me as a prospect for future tech, it’s how utterly industrial it is. It comes from a time when what we thought of as high-tech was giant computer mainframes and huge, powerful rockets. Freeman Dyson came up with the idea before we even had Star Wars and Star Trek, which themselves imagined a future with behemoth city-like starships, gargantuan space stations, and near-instant terraforming of worlds (and, eventually, the hyper-industrial Borg). For the idea of a Dyson Sphere, we have a massive industrial enterprise, the ultimate public works project, with structures of presumably enormous size and power forming a lattice or shell around an entire star or galaxy, sucking up the energy and venting out the waste.
It just seems, well, a little low-tech, doesn’t it?
I can’t speak to its relative probability, but Karl Schroeder’s view of a an advanced civilization integrating with, rather than consuming, its habitat makes more sense, especially if said civilization has managed to last long enough to get to this advanced stage. Any civilization that’s been machining its way up the Kardashev Scale might be more likely to exhaust its available resources more quickly, as opposed to a civilization that emphasizes equilibrium over growth. In this scenario, tech is small, geared to consume as little energy as possible, and population levels are more or less static, and there exists no drive to be fruitful, multiply, and conquer.
For Kardashev’s sake, how would we distinguish these two lines of civilizational ascent? Perhaps the numbers (Types 1 through 3 and so on) represent a Kardashev Industrial Scale, based on production and growth, while the other is the Kardashev Integrative Scale (or the Schroeder Scale?) based on ecological equilibrium and cultural advancement, signified with letters (Types A, B, C, and so on, where we modern humans would be very much sub-A).
Of course, we’d never be able to detect civs advanced on the Integrative Scale, unless they wanted to be detected, or reached out to us themselves. And since a hallmark of their advanced state is their utter lack of waste, it’s hard to see why they’d want to.