Mark Megahan
Any fan of classic science fiction is familiar with the concept of surrounding a star with scaffolding to harvest the energy emitted. Such “megastructures” are known in astrophysics circles as “Dyson Spheres,” named for physicist-engineer Freeman Dyson. While finding enough material to build a shell all the way around a star is quite a challenge, even for aliens, a more practical alternative is a “Ringworld” style band around a sun, as described by Larry Niven starting all the way back in 1970.
The search for Dyson spheres
Like most of the concepts thought up by Dyson, his idea of megastructures to capture stellar energy by surrounding the host star makes so much sense that astronomers are trying to find some.
They came to the conclusion that even a partial Ringworld type structure would cause starlight to blink bright and dim in the infrared light spectrum. Then they had a better idea.
Recent research gives astrophysicists “a new detection method.” Dyson Sphere structures and components may also “cause its host star to swell and cool.”
The megastructures are featured prominently in the video game “Stellaris.” Freeman first came up with the idea in the 1960’s. Ever since then, his students have been wondering how to spot one.
A full Dyson Sphere would virtually encase an entire star. That presents more than a few serious design challenges. First, a shell would find it “difficult to maintain” the proper orbit.
Then there is the raw material problem. There “might not actually be enough material in an entire solar system to do so (even if you took apart all the planets in the system).”
A partially encased star
The scenario of a “partially encased star” as the case with Niven’s Ringworld would also show in telescopes as unusually dim. That’s why, in 2015, everybody started talking about KIC 8462852.
Affectionately known as “Tabby’s Star” in honor of Astronomer Tabetha Boyajian, it “dimmed so much, some suggested that perhaps a huge orbiting megastructure had partially blocked our view.” Could this be an elusive Dyson Sphere megastructure?
Ms. Boyajian was “lead author on a paper announcing the discovery of the star’s 22% dimming.” The normal number is less than 1 percent. What could be blocking a quarter of the star’s light? Astronomers gave it a really good squint and ended up disappointed.
Rather than a Dyson Sphere, “the dimming is more likely a natural phenomenon caused by debris in the system.” SETI equipment searching for ET’s trying to phone home followed up on Tabby’s Star but “turned up no detectable artificial radio signals.”
Now that we know to look for “waste heat emitted by a Dyson Sphere” The soon to be launched James Webb Space Telescope will be looking at the universe with eyes especially adapted to the infrared spectrum.
Macy Huston and Jason T. Wright of Penn State University will be paying close attention. They came up with the notion that when “encapsulating a star with a megastructure, the star may begin to experience feedback of its own energy.”
