The Meerkat of Science!: Dyson Spheres
Alright, so this is a Meerkat of Science! post, but I’ll freely admit we’re getting into the realm of the fantastical here. Dyson Spheres are a hypothetical concept, born in science fiction yet forming a discussion around the Kardashev Scale (a scale devised by Nikolai Kardashev, a Soviet astrophysicist). The idea was first brought to light by one Olaf Stapledon in a book called Star Maker, and physicist Freeman Dyson revised it, developing the theory that a sufficiently advanced civilisation would seek to harness the output of its host star as its energy needs grew.
The energy needs of any given civilisation certainly climb as its sophistication developments. Humanity consumes more power than it did one hundred years ago, and in another hundred years our requirements will have grown, but if and when we reach the stage where we need to harness the sun’s output, there are only so many ways to do it, and a Dyson Sphere is a theoretical construct that could do just that. It would an enormous feat of engineering to build a sphere around the sun, with sufficient means to capture and then distribute that solar energy to earth, but if we could do it, it would wipe out so many problems in one fell swoop. Still, for now it remains in the realm of fantasy, but could it be a reality for humanity, one day?
We might one day need that sort of energy. To power the full-scale colonisation of the solar system, and perhaps beyond, in safe, reliable and meaningful ways, we’ll need a lot of resources. We might even need it simply to make sure we can survive on earth. If we were able to build something that harness ‘only’ 10% of the sun’s output, that in itself would revolutionise our world.
Assuming the theory is sound, and that it’s feasible for an advanced enough society to build one, a Dyson Sphere might be one of the clearest indicators of an alien civilisation. It wouldn’t even need to be a full-scale Dyson Sphere. A partial sphere, or even a Dyson Swarm around a star, would reduce the flow of light from that star, as seen from earth. Indeed, in the eyes of Dr Dyson, a swarm of objects or some form of lattice structure would make more sense than one huge sphere, and it would be less challenging from an engineering perspective. Astronomers have kept an eye out for stars displaying atypical behaviour for their size and spectral type, and down the years a few candidates have emerged, albeit not usually for long.
This hasn’t stopped speculation, and one particular star, KIC 8462852 (known informally as Tabby’s Star) has displayed unusual variations in luminosity that caught the attention of the media and the public. The variations have explanations rooted in natural phenonema, but so far none of them can completely explain the star’s varying brightness. That being said, the concept of Occam’s Razor (namely that the most plausible answer is the one that can explain the facts through the smallest number of mechanisms) renders a Dyson Sphere or Swarm extremely unlikely. This hasn’t stopped people from wondering, indeed perhaps hoping, that some of these stars are indicators of alien civilisations. On th other hand, perhaps we ought to temper such enthusiasm. A species that has learned to build such impressive structures and harness the power of their sun would be formidable. We may want to fly under their radar!
Here’s a more frightening idea. Under the Kardashev Scale, where energy consumption and needs determine how advanced a civilisation is, humanity would not yet even be a Type I civilisation. We have not yet learned to harness and store all the energy produced by our planet. A Type II civilisation would be managing this on solar scales. A Type III civilisation would be harnessing the energy of an entire galaxy, including the black hole at the centre. To a Type III civilisation, even a Type II would be a bug on a windshield, so what would that make us? A galactic Dyson Sphere or Swarm is well-beyond our ability to fathom, but then again, if you told the Victorians in 1826 that one day we’d be splitting atoms for energy, they’d have thought us to be fantastical creatures. There’s no telling what we might discover and learn to do, but let’s hope we aren’t visited upon by something that’s already done it, that decides it needs earth more than we do!
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