The fundaments of a Dyson Sphere

Humanity has always struggle in the search of new power sources, almost everything in our lives work with some kind of power, phones are charged with electricity, cars tend to use fossil fuels to generate their motion, even clocks used to need to be winded from time to time to function. The power consumption of humankind grows every year at a steady rate; new technologies allow new means to use energy, and thus the demands of energy also grow.

There are several means of producing energy: hydroelectric plants, nuclear reactors, fossil fuel combustion, Eolic turbines and so on, some give more energy than others, some are safer, cheaper or make a lesser impact on the environment. The truth is that mankind as a whole wants more energy with each passing day, so we are required to find new and creative ways to produce energy. In 1960 Freeman Dyson theorized a way in which we could harvest the power (or a fraction of it) of a burning star, like the sun, this has been called a “Dyson Sphere”.

The idea of a Dyson sphere was first exposed in “Search for Artificial Stellar Sources of Infrared Radiation” by Freeman John Dyson as an article for Science, in said article he theorized with a thought experiment that an alien civilization with 3000 years of industrial development (taking the average grow rate of 1 %) could have the means to fully utilize an amount of materials the size of Jupiter, and process those in a way that could retain the energy output of a star like our sun.

Since the idea was first proposed, it has been a common misunderstanding of the concept to think that a star can be contained in a hollow shell, this would mean for a sphere of 1 AU of radius, a surface of at least 2,82x10¹⁷ Km², which implies a exuberant amount of materials to build it, to demonstrate this, let’s suppose a constant thickness of just 1 meter, this gives 2,82x10²³ m³, using the density of structural steel (7850 kg/m³) as a reference (Far stronger materials than we know of would be needed) we get 2,22x10²⁷ kg, given that the total mass of earth is around 5,97x10²⁴ kg we can argue that more than a planet would need to be process to be able to build such mega structure.

There are several other problems with the proposal of an entirely closed shell around a star, like the stresses the structure would have to endure, this is why the actual idea of Dyson was a net of energy collectors, far spaced between each other around the star, this is called a Dyson Swarm, and could be a actually achievable through self-replicating robots, and a couple of moon or asteroids worth of the right materials.

A disadvantage regarding a Dyson swarm, is that every collector should be able to orbit around the star in a way that doesn´t interfere with another energy receptor, this could lead to very complex orbit calculations, but this can be solved with another form of Dyson Sphere, a Dyson bubble, that consist on the same concept as the swarm, but using stationary solar sails, which stay in place due to solar radiation, so technically, we could start building a Dyson swarm in the not so distant future, maybe a couple of hundreds of years to locate the material, and create the first group of self-replicating robots.

According to Freeman, we should be able to recognize an alien civilization that poses this kind of sphere by studying the radiation emissions of the stars, because such mega structures would change the radiation output of a star. Astronomers have seen two stars with a great flux in their radiation called KIC 8462852 and EPIC 204278916; the first one presented a decrease of 22 % and the second 65 %, but these changes have acredited to other hypothesis like a cloud of asteroids passing through, or a rotating circumstellar disk of dense gas and dust covering the said stars.

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Sources

• ''Search for Artificial Stellar Sources of Infrared Radiation'' by Freeman John Dyson
• Researchers Just Found a Second 'Dyson Sphere' Star