Eventually, every stellar civilization will have to migrate to a different star. The habitable zone around all stars changes as they age. If long-lived technological civilizations are even plausible in our universe, migration will be necessary, eventually.
Could Extraterrestrial Intelligences (ETIs) use stars themselves as stellar engines in their migrations?
In broad terms, a stellar engine uses a star to generate work. A simple example is solar panels, which use the sun's radiation to generate electricity that we use to perform work. But the scaled-up idea is to use the star to produce thrust. That thrust could be used to move the star itself. An ETI capable of doing that would be a Type II civilization on the Kardashev Scale.
To most of us, it seems like a wildly improbable idea. But who knows what's out there? If an ETI can survive long enough, it may become a Type II civ.
The stellar engine idea dates back to science fiction author Olaf Stapledon. A couple of decades after Stapledon, astronomer Fritz Zwicky also discussed manipulating stars with advanced technology, even turning them into spacecraft. In the decades since, the idea has persisted, and other researchers have delved into it. In 1988, Leonid Shakdov developed the first detailed stellar engine model called the Shakdov Thruster.
In new research, Clement Vidal, from Vrije Universiteit in Brussels, Belgium, examines how an advanced civilization could use a binary star as a stellar engine. The paper is titled "The Spider Stellar Engine: a Fully Steerable Extraterrestrial Design?" and it is available on the arXiv preprint server.
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