Humans are always full of energy, and this can be seen in a variety of superhero movies. From the cold nuclear fusion reactor of Iron Man’s suit, to the Zhenjin battle suit in the movie “Black Panther”, to the infinite energy in the movie “Sea King”, the high intelligence society is always associated with energy.
In real life, with the development of civilization, our demand for energy will also grow rapidly. In order to leap to a higher civilization, mankind will eventually be satisfied with the energy of the earth and seek help from the sun.
In 1959, physicist Freeman Dyson envisioned an artificial celestial body around the sun – the Dyson ball. It is a massive solar-collecting structure that corresponds to the Caldashof II civilization. Since its introduction, Dyson Ball has become an important research topic in astrophysics and engineering. So what should Dyson be like? How do we build it?
When Dyson made his own suggestion, he envisioned three different types of Dyson spheres: Dyson Shell, Dyson Cloud, and Dyson Bubbles. Let’s take a look at them one by one.
In science fiction, the most common is the Dyson shell, which is a solid spherical shell that completely surrounds the sun and receives 100% of the radiation from the sun. However, this form of Dyson’s shell is not realistic.
First, the construction of giant structures that envelop stars requires a lot of material, probably more than the existing solid materials in the solar system. Secondly, if you want the Dyson shell to have artificial gravity, it must rotate around the sun at a speed of 1200 km/s, which is 0.4% of the speed of light, which is equivalent to a week around the sun in a little more than a week. At this time, the internal stress of the Dyson shell is also huge, and no material has been found to withstand it.
However, although the Dyson shell is not practical for a star as large as the sun, for smaller stars like the M-class red dwarf (the star mass is less than 0.4 times the mass of the sun), the Dyson shell is still possible. . The Dyson shell has a large surface area, and the solid spherical shell is of sufficient mass to create a gravitational effect on the surface, allowing organisms and objects to stay on the surface of the Dyson shell rather than floating in space, so the Dyson shell is a potential biosphere. This is also a revelation for us to look for aliens. Some aliens may live in such a Dyson shell.
Dyson Cloud is a group of satellites carrying solar panels placed in the sun’s orbit. In order to collect more energy, these solar panels must be very large, and Dyson Cloud needs to offset the gravity caused by its own weight while collecting solar energy.
The advantage of Dyson Cloud is that it can be built step by step. We can launch a satellite first and then apply the energy collected by this satellite to the next satellite. However, as more and more satellites orbit around the sun, the configuration of satellite orbits becomes difficult, and scientists need to be careful to avoid the intersection of orbits and periodic solar eclipses caused by orbital overlap. Moreover, the collision of satellites with comets, asteroids and meteors will destroy the orbital arrangement, and the gravitational interaction with other planets will also affect the satellite orbit. In addition, because the surface area and mass of a single satellite in Dyson’s cloud is relatively small, providing little gravity, it is difficult to use as a human biosphere. When using Dyson Cloud to gain energy, humans still need to live on Earth or other planets.
Similar to Dyson Cloud, the Dyson bubble will consist of a large number of satellites that collect solar energy around the stars. The difference is that these satellites are not placed in orbit around the star, but are placed at a golden distance. At this distance, the pressure from the solar wind and radiation is exactly equal to the sun’s gravitational pull on the satellite, which makes each satellite completely stationary.
In theory, a civilized country can continue to add more satellites until the entire star is covered, which is equivalent to creating a Dyson shell. At the same time, it eliminates the possibility of other satellites causing eclipses, as each satellite remains stationary.
However, building Dyson bubbles may be more difficult than building Dyson clouds because gravitational interactions and collisions have a greater impact on it. Gravity effects or impacts do not completely dissipate Dyson Cloud, and in most cases they simply derail the satellite. However, the stationary Dyson bubble benefits from the precise structure of all satellite arrangements, and a very small interaction may destroy the stability of the entire structure, which may cause them to fall into the sun. Therefore, Dyson bubbles require a very advanced control system. Of course, Dyson bubbles can’t provide a suitable biosphere for humans, for the same reason as Dyson Cloud.
How to build Dyson Cloud
Considering the characteristics of the three forms of Dyson’s ball, constructing Dyson Cloud is more practical for us.
Assume that Dyson’s orbital radius is 1 astronomical unit (ground-day distance), and the radius of the sphere is about 2.8×1017 square kilometers. Even if we don’t ask Dyson to completely encircle the entire sun, we need a lot of satellites and the materials needed to build the satellite. At the same time, it takes a lot of energy to make satellites and send them to orbit.
In order to get a huge amount of material, we may need to dismantle a whole planet. Among all the candidate planets, Mercury seems to be the best choice, it is very close to the sun and is rich in metal. Mercury’s mass is 3.3 × 1023 kg, more than half of which can be used as raw materials to produce solar collectors. Mercury has no atmosphere, and its surface gravity is only one-third of that of the Earth. Relatively speaking, it is easier to send satellites into space.
In addition, the design of the solar panel should be relatively simple, with little maintenance, it can float in space for a long time, and the cost is cheap. Therefore, they are most likely to be a huge mirror on one side, directing the sunlight to the central collection system.
Due to the harsh environment of Mercury, the entire process of mining raw materials, building panels and launching satellites is done by a number of automated machines, including: solar collectors, mining machines, refiners and launchers. We can place a batch of solar collectors, use the collected energy to mine ore, refine rare elements, and manufacture and launch satellites. The launched satellites can provide more energy, so the satellite launch speed can grow exponentially.
Looking for traces of Class II civilization
Although humans are still thinking about how to build Dyson’s ball, such a giant building may already exist in the universe.
For example, in 2015, when the Kepler Space Telescope (specially observing changes in the brightness of a star) aimed at an otherwise inconspicuous star, the Tabby Star, its brightness showed a very strange drop, its brightness changes. There are no rules at all, which precludes the possibility of a single celestial body such as a planet orbiting it. Many scientists speculate that this strange drop in brightness is most likely caused by the Dyson ball of the alien civilization. Of course, another, more likely explanation is that huge dust clouds block light. In any case, the TBI star reminds us that Kepler may detect not only exoplanets, but also traces of advanced civilization.
If Dyson Ball is a necessary stage for the development of Class II civilization, we can reveal the existence of them and alien civilizations through some identifiable features of Dyson Ball.
From the events of the Tabby Star, we can see that the eclipse is an identifiable feature of the Dyson ball. If we witness a larger eclipse, but the star does not have a corresponding position to swing (the planet will cause the star to sway slightly), which shows that we are likely to find a Dyson cloud. Similarly, if we see a star appearing an extremely slow solar eclipse caused by a huge, dark celestial body, then the celestial body is probably a Dyson bubble. Because the Dyson bubble is stationary relative to the star, it will only follow the star slowly moving relative to us and cause a solar eclipse.
Dyson’s shells may be more difficult to detect because they completely absorb all the visible light emitted by the stars, so they are not visible to any conventional telescope. However, we can detect the radiation of the Dyson shell – infrared radiation. In general, a race does not use 100% of the energy collected by the inner surface of the Dyson shell, and they use energy to generate heat, and the remaining energy radiates from the outer surface at a lower frequency. If we detect a very large low-frequency infrared source, it is likely to be the accompanying effect of the Dyson shell.
As we approach the level of interstellar development, the exploration and discovery of the universe requires more energy, and making full use of the sun is an inevitable choice. No matter what form of Dyson ball, it represents a turning point for a race to become an interstellar race.
Kardashian Shove level
in 1964, the former Soviet astronomer Nikolai Kardashev proposed three levels of classification level of civilization development, he believes its level of civilization can master the resource-related because the more developed civilization, its The demand for energy is higher.
In the Caldashof class, Class I civilizations have mastered the resources of their planet, Class II civilizations can take advantage of all the energy of a star, and Level III civilizations can take advantage of all the energy of a single galaxy. At present, human civilization is in the late stage of level 0 civilization. Scientists predict that humans will soon be able to fully control the resources of the entire planet, and then humans will need to build a Dyson ball to gain the energy of the sun.