It's a fact that the more advanced humanity gets, the more energy we need. Between 1965 and 2015, the world's energy consumption nearly tripled. Who knows how much energy we'll need in another 50, 100, 1,000 years? Scientists assume it's no different for alien civilizations. There will be a point when the energy resources they can tap from their planet's surface are no longer enough. Never fear — they'll probably have a Dyson sphere.
Come Out of Your Shell
Dyson spheres are the stuff of futuristic science fiction, so it might surprise you to learn that they were first conceived way back in the 1930s. In his 1937 sci-fi novel "Star Maker," Olaf Stapledon wrote about an advanced alien community that "began to avail itself of the energies of its stars upon a scale hitherto unimagined. Not only was every solar system now surrounded by a gauze of light traps, which focused the escaping solar energy for intelligent use, so that the whole galaxy was dimmed, but many stars that were not suited to be suns were disintegrated, and rifled of their prodigious stores of sub-atomic energy."
Well, it turns out that scientists read sci-fi. Theoretical physicist Freeman Dyson was so inspired by Stapledon's idea that in 1960, he published a paper in the journal Science laying out why and how an advanced alien civilization might create such a device — and how we might detect it if they did.
Dyson used our own situation as an example. Currently, even our best solar panels can only collect a small fraction of the energy the sun produces, since most of it radiates out into space. But if we could somehow collect all of that energy, we could increase our energy resources by a mind-boggling margin. He also figured that over a few thousand years, we may be able to mine the solar system for supplies roughly equaling the mass of Jupiter. With those supplies, we could conceivably build a "spherical shell" (which he later clarified to be a "loose collection or swarm of objects traveling on independent orbits") sitting at twice the Earth's distance from the sun — between what would be left of Mars and Jupiter. That shell, or Dyson sphere, as it's now called, could theoretically collect every last bit of energy from our home star.
Dyson was quick to point out that he wasn't suggesting this would happen to us; just that it may have already happened in other solar systems. And if it has, there's a way to look for it. "The most likely habitat for such beings would be a dark object, having a size comparable with the Earth's orbit, and a surface temperature of 200 deg. to 300 deg. K," Freeman wrote. "Such a dark object would be radiating as copiously as the star which is hidden inside it, but the radiation would be in the far infrared." If astronomers ever find an object that's dark in visible wavelengths of light but bright in far-infrared wavelengths — dark and hot, basically — bingo. We've probably found E.T.
It's been more than half a century since Dyson proposed this new way of searching for alien life. Have we found anything?
Hello? Is It Me You're Dimming For?
We've certainly thought so. In 2015, Tabetha Boyajian discovered a mysterious object that acted kinda weird. Dubbed "Tabby's star," this star would experience weird fluctuations in its brightness, sometimes staying constant for a long period of time, other times dimming by a fifth and going bright again, other times dimming and brightening sporadically in rapid succession. You know, the way a star might dim if a Dyson sphere was being built around it.
The star was so mysterious that Boyajian and her team raised more than $100,000 on a Kickstarter to help them study it. In January 2018, they had their answer: dust, probably. The dips in brightness changed depending on the color of light the team was measuring. If it were an alien megastructure like a Dyson sphere, you'd expect all of the colors to be blocked at once.
But just the fact that scientists considered a Dyson sphere within the realm of possibility shows just how viable they believe this idea to be. As for now, we'll keep looking for dark, hot objects. If there's a Dyson sphere out there, it might show itself someday.
If you want to read the novel that inspired the concept of a Dyson sphere, you can: Olaf Stapledon's "Star Maker" is on Amazon. We handpick reading recommendations we think you may like. If you choose to make a purchase through that link, Curiosity will get a share of the sale.
What Is a Dyson Sphere?