Named after its creator Freeman Dyson, a Dyson Sphere is a proposed megastructure that encompasses a star and uses a large, if not all, of its power output. Considered to be a necessary stepping stone for civilizations in the Kardashev Scale, this popular science-fiction structure has one goal — to use the complete power output of a Star.
The Earth receives a lot of energy from the Sun, approximately 174 × 10¹⁵ W of energy. The average electricity consumption for the entire planet would be just a small fraction of this amount. However, this pales in comparison to the complete power output of the Sun, which is 2.2 billion times what we receive. Tapping into this energy source would be as revolutionary as the discovery of fire for humankind but as a spacefaring species.
How could we build a structure capable of harvesting this energy? A solid sphere around the Sun or any star would be impractical, as no material would be capable of handling the strain created, hence the irony in the name Dyson Sphere. However, a swarm of structures, statites, could be employed, built to float on solar radiation. A swarm of these is typically known as a Dyson Swarm and is a more practical approach to constructing a Dyson Sphere.
Building a structure of this magnitude requires abundant resources and potentially, the cannibalization of a planet to obtain the necessary material. There are other ways to get resources using the star itself, but we will discuss this method later. The direct way would be to mine a planet close to the Sun or an asteroid rich in mineral content and utilize the mined material to begin constructing statites. A statite is a type of satellite that would employ a solar sail to float on the radiation of the Sun. This allows it to stay in positions not allowed by stable geosynchronous orbits.
Power at this scale is incomprehensible to us, so what use could any civilization have for this much power? Dyson Spheres can be outfitted for many purposes. They can be modified to meet the current demands of whatever its creators require.
Firstly, Dyson Spheres could be used for creating living spaces. Creating a Dyson Sphere with a swarm of smaller structures suited for housing people in Space such as O’ Neill Cylinders or McKendree Cylinders would result in a massive habitable swarm which would dwarf Earth the same way Earth dwarfs a small village or town.
One might wonder, what if we put the power output of the entire star into computational purposes? The result of that thought experiment is the Matrioshka Brain. The name comes from the Russian Matryoshka dolls, a series of nested dolls each decreasing in size and inside the previous. Similar to how the Matryoshka dolls are nested in one another, the Matrioshka Brain consists of several layers, each working together to perform calculations. The logic behind the nested layers is that each layer runs calculations at very high temperatures via the absorbed sunlight, later emitted as waste heat which is then absorbed by the next layer. The next layer emits the waste heat at a slightly lower temperature.
The computational power of such a structure is unimaginable. It would be capable of performing insane feats; for example, it could simulate trillions of worlds simultaneously throughout their entire history in less time than it takes for us to blink. Whole-brain emulations, simulations of trillions of human minds, solving questions related to the universe and more can be achieved with a Matrioshka Brain. We could even convert the entire Matrioshka Brain into a single intelligence, a god mind, running on the energy output of a Star. Humanity would be mere ants compared to this intelligence.
Starlifting is a process by which we extract the matter in the form of Hydrogen from a star and reuse it to either get other elements, create heavy elements via transmutation, or possibly extend the lifetime of the star and to prevent it from exploding. A relatively advanced operation such as this requires a large amount of energy. A simple way of starlifting would be to reflect its radiation back at it to heat portions of the star, resulting in thermal eruptions at the surface similar to a solar flare, which would eject mass. The alternative to using an entire planet for creating a Dyson Sphere, as mentioned earlier is this. By collecting mass from the star and transmuting it into the required materials, we could begin assembling portions of the Dyson Sphere using mass stolen from the star.
Shkadov structures are a megastructure used, either to move planets around in a star system or around entire star systems. The concept is simple — it involves using giant mirrors located around a star to push back solar radiation and accelerate the star in the mirror’s direction. This would allow civilizations to avoid contact with dangers coming their way in the far future, such as supernovas, black holes, neutron stars and other massive objects which have debris orbiting them.
While a star such as our Sun does emit several photons, it also has a great mass, which would mean for the thruster to have any effect we would have to keep it operating for millions of years for it to produce any significant delta-v. However, if we can see dangerous situations coming our way millions of years before they arrive; then this will not be a problem.
A faster way to deal with stars going supernova would be to move the star away instead of trying to move our system out of the supernova range. A star which will go supernova in the future will be emitting more photons and have a higher luminosity compared to our Sun, which would mean a Shkadov Thruster would be better suited to it.
A Dyson Sphere doesn’t need to be dedicated to only one of these purposes. In fact, it would make more sense to dedicate portions of the Dyson Sphere for different purposes -if a particular area is used for living space, others could be used for resource and power collection, etcetera.
So far, everything we discussed has been about the hypothetical effects of the Dyson Sphere. How does this megastructure have any real-life relevance? Well, the Dyson Sphere could be critical in the search for intelligent extraterrestrial life. As a civilization grows, it presumably grows outwards and would be met by an increase in energy demands. Eventually, it would need more energy than the planet could provide, and hence the logical conclusion is that it will draw energy from its home star. Thus looking for a Dyson Sphere might be a possible way of locating life in the vast universe. Since constructing one would affect the spectrum output of a star, it would be quite hard to hide a Dyson Sphere. Looking for artificial sources of infrared radiation might be the key to finding intelligent life out there.
And so far there have been two possible sightings which would match the output of a Dyson Sphere. KIC 8462852, a star in the constellation Cygnus 1,480 light-years away from us, was observed to have a strange dimming phenomenon. When a planet passes between an observer and a star, the brightness of the star is expected to dim by 1%. However, it was noticed that the star dimmed by a shocking 22%. The second star to display this strange phenomenon is called EPIC 204278916 dimmed by 65% for two days consecutively. An initial explanation for this dimming was that a cloud of comets happened to be orbiting the Sun. However, the number of comets which required to produce this is very high and unlikely. An explanation put forward by the German team behind these observations suggests that the dimming could be due to a protoplanetary disk around the star, which is a dense disc of gas and dust which surrounds a newly formed star. This explanation may be plausible as EPIC 204278916 is a relatively young star, only a few million years old.
Regardless of whether these observations are actually Dyson Spheres or not, searching for such stellar megastructures might be the key to finding intelligent life out there; or if we choose to, let others find us by constructing one ourselves. It would take us a tremendous effort but in the end, it would have a considerable reward.