Solar-powered megastructures called Dyson spheres sound like science fiction, says physicist Isaac Arthur, but the reasons to construct an energy farm are clear.

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A Dyson sphere is a megastructure that encloses a star and captures its energy. Civilizations could build these with basic power satellites and orbit them around the sun. What you’re doing isn’t making one big shell, but making trillions of these, he said.

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Solar tech is already big business, and it’s not hard to imagine a future industry based on high-efficiency solar power at massive scale. Though constructing a Dyson sphere may seem preposterous, said Arthur, consider companies like SpaceX and Blue Origin. “It’s not hard to build them,” Arthur said. “We have the technology to do it now. It’s just we don’t have the infrastructure and space to do it.”

Megastructures capture a large amount of energy that can be used to run transmutations and make heavy elements that could be used in construction. It could also be used for interstellar travel.

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