Dyson sphere

A Dyson sphere is a hypothetical megastructure that completely encompasses a star and captures most or all of its power output. The concept was first described by Olaf Stapledon in his science fiction novel Star Maker (1937), and later popularized by Freeman Dyson in his 1960 paper "Search for Artificial Stellar Sources of Infrared Radiation". Dyson speculated that such structures would be the logical consequence of the escalating energy needs of a technological civilization and would be a necessity for its long-term survival. He proposed that searching for such structures could lead to the detection of advanced, intelligent extraterrestrial life. Different types of Dyson spheres and their energy-harvesting ability would correspond to levels of technological advancement on the Kardashev scale.

Since then, other variant designs involving building an artificial structure or series of structures to encompass a star have been proposed in exploratory engineering or described in science fiction under the name "Dyson sphere". These later proposals have not been limited to solar-power stations, with many involving habitation or industrial elements. Most fictional depictions describe a solid shell of matter enclosing a star, which is considered the least plausible variant of the idea. In May 2013, at the Starship Century Symposium in San Diego, Dyson repeated his comments that he wished the concept had not been named after him.

The concept of the Dyson sphere was the result of a thought experiment by physicist and mathematician Freeman Dyson, when he theorized that all technological civilizations constantly increased their demand for energy. He reasoned that if human civilization expanded energy demands long enough, there would come a time when it demanded the total energy output of the Sun. He proposed a system of orbiting structures (which he referred to initially as a shell) designed to intercept and collect all energy produced by the Sun. Dyson's proposal did not detail how such a system would be constructed, but focused only on issues of energy collection, on the basis that such a structure could be distinguished by its unusual emission spectrum in comparison to a star. His 1960 paper "Search for Artificial Stellar Sources of Infra-Red Radiation", published in the journal Science, is credited with being the first to formalize the concept of the Dyson sphere.

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