Dyson Sphere: How to Harness a Star’s Energy for Use by People and Aliens

A Dyson sphere is what? How does a Dyson sphere work? Could they be behind the strange signals coming from space?

What is a Dyson Sphere?
A Dyson sphere, also known as a megastructure, is an enormous, fictional mechanical structure designed to capture the power of stellar nuclear furnaces. The core concept is that a structure is built around a star that transforms, stores, or makes use of the star’s radiant energy.

The most likely, essential, and cost-effective method of meeting the enormous energy needs of future human civilization, and perhaps advanced extraterrestrial civilizations elsewhere in the cosmos, is theorized as such facilities.

Uma esfera de Dyson é uma megaestrutura hipotética construída em torno de uma estrela para utilizar a energia dessa estrela © Getty images

Who theorized them? And when?
The Dyson sphere theory is named after physicist Freeman Dyson (1923–2020), who in 1960 presented it in a short academic paper on techniques for finding extraterrestrial civilizations. However, Dyson acknowledged that the renowned science fiction book Star Maker (1937) by British author Olaf Stapledon served as an inspiration.

Every star in the universe is surrounded by “a web of light traps”, according to Stapledon in Star Maker, which “directed the drain of solar energy for intelligent use”.

As esferas de Dyson funcionam aproveitando a energia colossal liberada pela estrela hospedeira © Getty images

Since then, other scientists have looked at the Dyson sphere idea again, often as part of SSETI research.

How do Dyson spheres work?
The function of a Dyson sphere is to collect the enormous energy that the host star emits. The fundamental technology to do this already exists in the form of “solar cells”. They employ a technique known as the “photovoltaic effect,” in which photons dislodge electrons from atoms to separate charge within a material and produce an electric current.

Whatever their shape, Dyson spheres are likely to use this mechanism to produce energy. Some researchers believe this energy will be transmitted wirelessly to nearby civilization, likely on a habitable planet in orbit around the host star.

Could Dyson spheres really exist?
Dyson spheres or anything comparable have yet to be shown to exist anywhere in the universe. Scientists, however, can comment on whether they are “permissible”.

First, while it is far beyond what ground intelligence is currently capable of, there are no known insurmountable obstacles to developing such a technology. Dyson spheres are undoubtedly viable with the right motivation, money and technological innovation. According to one researcher, humanity may try to do this in the next 100 years or so. That, according to some academics, is outrageously optimistic.

A Enterprise investiga uma esfera de Dyson em Star Trek: The Next Generation © Paramount Pictures

There are actually some restrictions on how many Dyson spheres can exist in the universe, according to astronomers. To achieve this, it is assumed that these structures would have an impact on the stars’ emerging brightness. For example, most designs would reduce their optical brightness by blocking some of their host star’s light.

They can also produce waste heat that would radiate as infrared light. One estimate states that up to 10,000 stars may contain Dyson spheres within a radius of approximately 16,000 light years from Earth (in comparison, the distance to the center of the Milky Way is approximately 26,000 light years). This could be done by carefully observing such deficits or excesses in the light of thousands of stars.

This only suggests that Dyson spheres might exist, not that they really do.

How were Dyson spheres represented in science fiction?
Although not Dyson’s original suggestion, science fiction writers often describe a Dyson sphere as a solid structure entirely surrounding a star. In fact, this interpretation is considered the least viable. However, fictional universes also feature satellite swarms and ring-shaped formations.

Postulou-se que as quedas aleatórias no brilho da estrela de Tabby poderiam ser atribuídas a uma esfera de Dyson © Science Photo Library

Fritz Leiber’s The Wanderer, Larry Niven’s Ringworld, and Stephen Baxter’s The Time Ships are some prominent books that use Dyson spheres or comparable ideas (1995). A Dyson sphere was depicted on television in the Star Trek: The Next Generation episode “Relics” (1992).

Could they be responsible for “strange” signals from space?
Many ‘weird’ or mysterious signals are emanating from space, but none of them are currently candidates for Dyson spheres.

A few years ago, the star known as “Tabby’s Star” exhibited sporadic dips in brightness that resembled a Dyson sphere; however, subsequent investigations proved that the true cause was the dust clouds surrounding the star.

How do you build a Dyson Sphere?
As the name suggests, one method involves building a spherical structure around a star (often called a “Dyson shell”). Such a structure would likely need to be both flexible and propelling to regulate the impacts of the star’s gravity and radiation pressure. However, other scientists claim that it may not be feasible to maintain stability in such circular formations.

Dyson spheres probably wouldn’t even be spheres. A Dyson “bubble” is a notion that describes ring structures, dense swarms of orbiting satellites, or swarms of “statites” (static satellites) that remain motionless relative to the star. Engineers have suggested that armies of space-based robots could build these constructs remotely, and that building materials could be collected by destroying terrestrial planets.

Dyson structures have also been theorized in other, more exotic forms, such as galaxy-sized clouds of “smart dust” that capture the energy of countless stars.

Pode não ser possível construir uma esfera de Dyson completamente esférica, e será necessário considerar os efeitos da gravidade da estrela e da pressão de radiação © Getty images

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