It is difficult to say when a person first thought about whether he is alone in the universe. But you can determine the time when the search for the answer to this question passed from the pages of science fiction novels into science - the middle of the last century, the beginning of the space age. With the development of interplanetary space, more and more ideas about extraterrestrial civilizations began to appear. Intergalactic wars were played on the pages of science fiction, and astrophysicists and astronomers tried to understand whether life in the vicinity of distant stars is possible. If so, how to detect it? Recent ideas include Freeman Dyson's theory. A sphere of enormous size, which allows one to accumulate the energy of a star, is what, in his opinion, is worth looking for in the vast space to find aliens.
Freeman John Dyson
An American scientist of English descent was born in 1923. Today, the 92-year-old Dyson, whose area of interest covers quantum physics, astrophysics, low-energy physics, is known as one of the creators of quantum electrodynamics. Almost to a greater degree, fame brought him the concept that the scientist borrowed from Olaf Stapldon, science fiction writer, author of the book "The Creator of Stars." The theory, called the “Dyson sphere”, suggests that highly developed civilizations can build a huge structure around the star in order to maximize the use of its energy. Having found such a design, scientists will be able to detect extraterrestrial intelligence.
Concept
A highly developed civilization, hypothetically existing in outer space, sooner or later will face the depletion of energy resources - this is the assumption of Dyson. A sphere with a radius of one astronomical unit with a star in the center can solve this problem. The impressive size design allows you to fully use the energy of the star and, if necessary, becomes home to its creators.
Parameters
The thickness of the sphere, according to Dyson, should be quite small. For the construction of such a structure, material that is close to Jupiter in mass is needed. Today, such a project looks like a very bold fantasy. However, it is impossible to exclude the possibility that after hundreds or thousands of years, mankind will be able to translate it into reality, and now in the vast expanses of outer space, the construction of such a structure is engaged in an extraterrestrial civilization that surpasses us in terms of development.
A star with a Dyson sphere obeys the same physical laws as planetary systems. Therefore, the structure must rotate: the force of centrifugal rotation balances the attractive force of the star and does not allow the object to collapse and fall on it.
Signs of advanced civilization
According to Dyson, the sphere can become a kind of beacon, noting the presence of extraterrestrial intelligence. However, how to find her? According to theoretical calculations, such a design should constantly emit light. For the human eye, it is elusive. The radiation should lie in the infrared part of the spectrum. Existing equipment can detect such sources, moreover, a lot of them have already been found.
A distinctive feature of the Dyson sphere should be an atypical spectral distribution. The search for a structure theoretically described by a physicist is being carried out within the framework of the SETI program, aimed at detecting the presence of extraterrestrial intelligence in space. The main hopes for this complex task are assigned to the Spitzer telescope.
Arguments against
Since its inception, Dyson's theory has been repeatedly rethought and cross-checked. As a result, a well-founded opinion appeared that such an object could not exist, no matter how developed civilization was or what characteristics the star possessed. The Dyson sphere, revolving around the luminary, acquires maximum speed near the equator. At the same time, the structure remains motionless at the poles, which will inevitably lead to its collapse. This is the main argument against the theory of the American scientist.
Researchers of the issue also note that the sphere spatially limits the development of civilization and gives rise to several significant sociocultural problems that overshadow the benefits of its creation.
Alternatives
However, in the scientific world, the theoretical development of Dyson has not sunk into oblivion. Several design modifications have been described that take into account key criticisms. The first of them is a ring of small width, as significant in diameter as the sphere. You can meet such an object on the pages of the novel "The World-Ring" by Larry Niven.
The second option is a design that resembles a spinning top in shape. Curved bulges in the region of the poles are open. This version of the sphere is characterized by the same weight at any point on the inside.
The Soviet physicist G.I. also proposed his own solution to the problem. Pokrovsky. In his model, the design consists of many rings forming something similar to a sink. This version of the sphere was called Pokrovsky’s shell.
Chriswell's structure is another modification of the astroconstruction proposed by Dyson. Its feature is a fractal surface, which allows to maximize the area perceiving star radiation.
Search for Dyson's hypothetical sphere
The theoretical development of the American physicist for more than fifty years. However, they began to seriously think about the search for structures similar to the sphere only in the 2000s, when the development of technology made it possible to look into remote corners of space. The analysis of information from telescopes showed that there are several hundred thousand objects suitable for the role of gigantic artificial structures. True, the characteristics of each candidate with different degrees of probability are explained by more prosaic reasons, among which comet swarms, hydrogen clouds, and so on are called.
One of the last contenders for a star surrounded by the Dyson sphere was the star in the constellation Cygnus. In astronomical catalogs, it is designated as KIC 8462852.
Dyson sphere discovered ?!
Last fall, a headline could be seen on the pages of the media reporting the discovery of the location of an extraterrestrial civilization. The star, near which intelligent creatures unknown to us live, was called KIC 8462852. The features of the luminary became known thanks to the Kepler telescope.
In the fall of 2015, the results of a study of its strange luminosity were published. About once every 800 days, star radiation decreases by 15-20%. Recession lasts from a few days to several months. Such behavior is not characteristic of the known classes of luminaries and cannot be explained by the passage of the planet through the disk, since in this case the decrease in radiation would always be the same in time. Jason Wright, a scientist at the University of Pennsylvania, suggested that the cause of this anomaly is the Dyson sphere. KIC 8462852 has thus become a prime candidate for the search for extraterrestrial intelligence.
Other explanations
Wright has repeatedly noted that this is only one of the versions, and the most unlikely. However, thanks to the media, the news of a possible discovery of the Dyson sphere scattered around the world. Meanwhile, there are other explanations for the star’s strange radiation. Researchers at Yale University, led by Tabeta Boyajian, suggest that the sun is surrounded by a swarm of comets. Perhaps KIC 8462852 several thousand years ago captured them at a time when another stellar system passed by. Tabeta notes that such an explanation is only slightly more likely than the Dyson sphere. The meeting of two stellar systems is a very rare event, and the volume of the captured swarm of comets must be huge. Nevertheless, this theory has so far gained the largest number of supporters in the scientific world.
Take a closer look at white dwarfs
Scientists from Turkey joined in the search for the Dyson sphere. Recently, they published a study according to which it is necessary to look for such a building with white dwarfs. The relatively small and cold objects of the cosmos represent the final stage of the evolution of the bodies of the sun. In their vicinity, the erection of a sphere requires less effort and material than around more massive stars. According to scientists, the thickness of the structure near the white dwarf would not exceed 1 meter. For its construction would require material, the mass of approximately equal to the moon.
Perhaps after some time, scientists will come to the conclusion that the Dyson sphere is an unnecessary or too complicated structure. However, while the search for a hypothetical design continues. It is safe to say that similar ideas will arise in the future, since humanity will not stop trying to find brothers in the mind in the open spaces.