Dyson Sphere - what is it for? Part I: History and the possibilities of translating the idea
The generally accepted priority in the invention of the concept of a colossal space structure, designated by the term “Dyson Sphere”, belongs to the Anglo-American scientist Freeman Dyson . But, as always in history, if you search well, you can find predecessors who expounded something similar, laid some foundations, based on which our contemporary Dyson could offer such a bold idea.
Freeman Dyson himself admitted that he was inspired by the idea of the science fiction novel The Star Maker, Olaf Stapledon, whose author Olaf Stapledon described a similar structure (rings around stars without planets and new artificial planets) as early as 1937.
')
But Olaf Stapledon could borrow the idea from another author: John Desmond Bernal (JD Bernal, “The World, the Flesh, and the Devil”) in the article “Peace, Flesh and the Devil” described spherical space colonies built of thin shells around transferred to new orbits of asteroids. He also implicitly hinted that when there are many such colonies, then they will intercept most of the energy of our luminary.
The founder of cosmonautics, our compatriot Konstantin Eduardovich Tsiolkovsky, also offered habitable space colonies, not in the form of a sphere, but in the form of a pyramid or cone, deployed with a transparent base towards the Sun (with plants and inhabitants located on the walls of the cone) - the so-called “ethereal cities". And here the scope of Dyson? And despite the fact that in the picture below from Tsiolkovsky’s diary it is clear that he depicted these cones precisely combined into an ordered network (what is not a part of the Dyson sphere?) With the help of certain beams or cables passing through the centers of these objects (bottom left):
In addition to these authors, American science fiction writer Raymond Z. Gallun also expounded something similar.
Even in the Middle Ages (15th century), the Italian thinker of the 15th century, Marsilio Ficino , foreseeing human capabilities in the future (intuitively feeling that human capabilities are developing on the basis of knowledge, that is, accurate human knowledge of the laws of nature), completely self-confident (for its time) wrote:
It should be noted that although the Dyson sphere is not an analogue of a star — a star or a planet, but in some sense it uses the first and replaces the second. The Dyson sphere can be understood not only a sphere, but any construction. The main thing is that this construction should be large-scale and intercept a significant part of the Sun's radiation (and not thousandths of a percent, as existing in our planet system). Of course, the Italian Marsilio Ficino in the 15th century could not invent the concept of the Dyson sphere (he lacked knowledge) and simply dreamed of creating a semblance of natural celestial bodies, but nevertheless he was able to identify in his short text three of the four main problems of creating a sphere by civilization Dyson:
1. The method of creation - in what way can one create a sphere with a radius of 50-250 million kilometers?
2. Means of creation - with what “ tools ” can one create such a sphere so as not to harm oneself and one’s entire system?
3. The material for the creation is the very " heavenly material " that determines by its presence, quantity and quality the very possibility of creating such a sphere (as well as the methods and speed of construction).
4. Location - which needs to be determined in advance, before construction, so that later it does not turn out that having a sphere in this place only complicates the life of a civilization or is simply dangerous for its system.
Let's start with the last problem - from the location of the sphere, since this is the most important decision, which significantly influences subsequent ones. And the answer to the question about the placement of the sphere directly depends on the purpose of the sphere.
Classification by location
Option A: If we need the Dyson sphere simply to obtain the maximum energy from the Sun (without taking into account the preservation of planetary illumination, especially the illumination of the Earth), then it would be more logical to arrange the sphere as close as possible to the Sun.
Three main problems arise:
Option B: If we need a sphere as a habitat surface for people (with all the necessary infrastructure, atmosphere, soil, plants and animals), then the sphere should be solid and located where the light of the Sun has about the same intensity as on the surface of the Earth - those. at a distance of the Earth's orbit or even further (to compensate for the absence or weakness of the atmosphere, the magnetosphere, necessary for protection from solar radiation).
Three new main problems arise (the above problems of Option A do not disappear, but go to the background):
Option B: If we need a sphere with a thin primitive (easily repaired) surface intercepting light from the Sun, but not necessarily solid (withstanding the soil, people), but with a maximum surface area and with minimal energy flow (so as not to worry about overheating the sphere) , the sphere should be located somewhere further away from the luminary.
For such a sphere, three main problems are also relevant (other problems are less important):
Classification by purpose
From a cursory examination of the location of the Dyson sphere, it is clear that much is also determined by the purpose of the sphere:
Assignment 1: Strong Energy Cocoon around a Star
As close as possible to the star, a rotating (not necessarily solid) durable cooled shell is created with catchers (as well as transducers and radiators) of energy - in order to obtain maximum energy with minimum construction volumes. How close to the sun can you build such a sphere? If we take the sun to warm up to 1000 K (without special cooling), then the radius will be about 23 million km, which lies inside Mercury's orbit (radius of its orbit is from 40 to 60 million km) - these calculations are taken from the list of answers to typical questions on the Dyson Sphere .
All received light energy is converted into another (for example, into electrical energy) and then either transferred somewhere (for example, by laser or radio wave), or applied on site. The state, light, stability of the orbits of the planets and even their very existence are not taken into account - if necessary, they are sorted into materials for creating a sphere.
Despite some extremes of this purpose of the sphere (the instability of the sphere must be constantly parried by the release of gases / solar wind from different directions, or by the operation of engines on the outer / inner shell of the sphere) and the problem of strength (for our development level, the main problem is the strength of any modern materials) It is fully justified for high level civilizations. Especially if such a way is mastered not by its own luminary, but by an alien star. This is not the cradle of civilization, where a hand will not rise (or out of respect for the history of its world), apart from disrupting the stability of the orbits of other planets when disassembling even one planet. If such an alien star has an unfortunate (from the point of view of civilization) spectrum, does not have planets suitable for exploration and dwelling, then no one will particularly regret such a system with a star: the planets will go to create a sphere.
The design of this type is especially optimal for white dwarfs : these inactive, slowly (billions of years) cooling stars remain shining steadily: their surface temperature cools at an average speed of about 10,000 K over 1 billion years - this estimate is based on the temperature difference of a new white dwarf: from 90 000 K (estimated by absorption lines) or 130 000 K (estimated by X-ray spectrum), to temperatures below 4000 K (the so-called black dwarf) for some white dwarfs, cooled over 13 billion years (the lifetime of the Universe). White dwarfs shine without flares and coronary mass emissions, they are small in size and luminosity - around them you can make a sphere with a radius ten times smaller (even less than 1 million km) than around the active Sun or other stars of similar size. But the problem of the strength of the sphere remains.
In 2015, two Turkish scientists calculated the radii of Dyson spheres (suitable for people to live on an external solid surface at room temperature) for different types of white dwarfs. The results are in the range of 2-5 million km, and the amount of material to create such spheres with a shell thickness of about 1 m is approximately equal to the material of the entire Moon. This work was noticed both in the USA and in our media .
Dealing with red dwarfs is a bit more complicated: they often have flares, their hard radiation is more dangerous than solar radiation. But they also have their advantages: there are many of them, and their weight is from 30% and up to 8% by weight of the Sun, considerably smaller luminosity values and small geometrical dimensions allow building spheres with a radius smaller than for the Sun, and the duration of their life is far away. overlaps both the life expectancy of the Sun and the cooling time of white dwarfs to a level when the sphere gains little energy.
Conclusion: This assignment of the Dyson sphere makes sense for certain types of small stars, but clearly not for the native system of civilization and not for the first attempt of any civilization to build the Dyson sphere. That's when civilization comes out into stellar spaces, then it will begin to “extinguish” the nearest stars (especially dwarfs) with such cocoons, thereby forming the Fermi bubble without stars in the sky (Richard Carrigan's term). In the optical range, it will look like stars in a nebula, but at the same time decently glowing in the IR range. The name “Fermi bubble” was suggested due to the fact that such a group of Dyson spheres will gradually expand in accordance with the assumption of Enrico Fermi about the rate of expansion of the range of such civilizations in 0.001-0.01 from the speed of light.
Appointment 2: A huge surface for the settlement of people
The most ambitious, difficult to create and financially expensive assignment for the Dyson sphere. Requires a truly huge amount of materials and resources to create. If we do not consider it possible to disassemble the Earth or darken it, then the radius of such a sphere should be about 190-250 million km (40-50 million km beyond Earth's orbit to reduce the mutual influence of the sphere and the Earth).
In connection with simple conclusions from physical laws (Gauss's Law) - the so-called Newton's theorem on the absence of gravity inside spherical bodies (in English: Shell theorem) - for any uniformly dense spherical shell, gravity inside the shell depends only on the mass inside (but not on mass of the shell itself). Therefore, it will be simply dangerous for people to be on the inner surface of such a shell: they will be attracted inward to the Sun, and not to the shell (no matter how thick it is). In connection with this, some originals even suggest settling on the outer shell of such a sphere ! (and the above mentioned work on white dwarfs ). It is possible to get rid of falling inwards: by twisting the sphere to the normal orbital speed for such a radius, which will add about 1/3 of the earth's gravitational force outward.
But the atmosphere will not be particularly confined (it must be protected from the internal vacuum), all the light from the Sun will re-reflect from the shell and blind from all sides, and the solar wind closed inside the sphere with an intensity of about 2.5 per 10 ^ 12 ions per square meter for a second can not go anywhere.
The main problem is different: it is necessary to achieve a considerable strength of the shell of this sphere so that the sphere does not fall inward towards the Sun under the action of the gravity of the Sun. For a non-rotating sphere, a certain strength is required to withstand the pressure caused by the attraction of the Sun to the test kilogram of the sphere material, which is equal to (calculations from here ):
Fin = G * M * m / R ^ 2 [kg * m / sec ^ 2]
where G = 6.674 * 10 ^ -11 [m ^ 3 / (kg * s ^ 2)] is the gravity constant,
M = 2 * 10 ^ 30 kg is the mass of the Sun,
m = 1 kg is the test mass per unit area of the sphere, and R is the radius of the sphere 190 million km
= 6.674 * 1.9885 * 10 ^ (30 - 11) / 190 * 10 ^ 9 * 190 * 10 ^ 9 = 3.6768 * 10 ^ 19/10 ^ 22 = 3.68 * 10 ^ -5 [kg * m / s ^ 2] = 0.04 millinewton.
This is like nonsense, some tiny fraction of the force of gravity on Earth (9.8 Newtons act on the test kilogram on the surface of our planet). But the problem is that the weight of all the other kilograms that make up the sectors of the dome of the sphere from below and from above (see the graphic drawing below) presses on this kilogram of the shell.
Yes, their weight at such a distance from the Sun is minimal, the same 0.04 millinewton, but this meager force must be multiplied vectorially by the millions of these kilograms that make up the mass of the dome sector. The resulting force depends on the thickness of the shell and even for centimeter thicknesses it is simply terrible (since the size and mass of the sector of the dome is huge).
If you create a rotating sphere (when assembling a sphere from elements, this is the only way to start: all elements of the equatorial ring must first be placed into a stable orbit, which requires rotation around the star at speeds close to the orbital speeds of the planets: 30 km / s for Earth or about 25 km / s for the orbit behind the earth, but before the Martian), then this rotation will help the assembled rigid shell of the sphere only at the equator and next to it. There, centrifugal acceleration (inertial force) is:
Fout = m * V ^ 2 / R [kg * m ^ 2 / m * sec ^ 2]
= 25 * 25 * 10 ^ 6/200 000 000 = 625/200 = 3.125 [kg * m / s ^ 2] = 3.1 Newton (3 times less than the earth's weight).
But this acceleration does not reduce the force of attraction to the luminary at the poles of such a sphere, and does not particularly help at middle latitudes. The problem with the pressure of a huge mass of sectors of the upper and lower domes on the rapidly rotating equator of the sphere remains. The problem of lack of resources remains: the scientist Anders Sandberg estimates that there is 1.82 x 10 ^ 26 kg of easily used building material in our Solar System, which is sufficient for building a Dyson shell with a radius of 1 AU, an average weight of 600 kg / m2 with a thickness of approximately 8-20 cm, depending on the density of the material. If one throws out the material of the core of gas giants, which, to put it mildly, are difficult to access, then the inner planets alone can provide only 11.79x10 ^ 24 kg of substance, which is enough to build a Dyson shell with a radius of 1 AU. with a mass of only 42 kg / m2 and about a centimeter thickness.
Conclusion: This assignment of the Dyson sphere only makes sense for idealistic dreams of the power of civilization. Modern materials do not allow to create such a sphere. In addition, no material and no new technologies will change the fact that the inner surface of the sphere is not suitable for living in its pure form (we also need an internal transparent sphere to keep the atmosphere from falling down towards the luminary), and the sphere itself is dangerously unstable. And most importantly: the material in our system is simply not enough.
Assignment 3: Light Star Energy Concentrators
Such spheres can be both farther and closer to the Earth's orbit. The main thing is that their purpose is not to live the maximum number of people on their inner surface, but to use the energy radiated by the Sun, if not 100% of this energy. These assumptions according to purpose open up wide possibilities in terms of forms and types of structures.You can choose the one that is available to current technologies, without threatening the unreal. For example, you can move away from the sphere to the individual elements that make up the so-called Roy Dyson, in orbit around the Sun (in Mercury) , which receive and process energy and send it further to consumers.
Elements with no energy conversion that simply send reflected sunlight in the right direction (mentioned here ) can also be considered . A set of such non-rigid rings (of swarm elements) with different radii and angles to the ecliptic plane can, in principle, intercept even more than 50% of solar radiation, even if the rings are not solid (not rigid) and there are gaps between the rings themselves.
Yes, this is not a sphere in the geometric sense of the word, but a completely practical alternative to the sphere. The main thing is to abandon the sphere itself - as they say: do you need to get there or do you need to get there?
Conclusion:This vague assignment of the Dyson sphere gives greater flexibility to the whole concept and allows us to consider several shapes and types of structures, with different initial tasks and with different results, as well as with different potentials for improvement and modernization.
The futurist Stuart Armstrong came to the same conclusion, choosing Roy Dyson (Dayson Swarm) as a natural perspective for civilization, built from Mercury material and located approximately in its orbit: see the same video above (from 2:50 to 4:50) in English, with arguments about the development of hematite (chemical formula Fe2O3) on Mercury, about reflectors and collectors of light. This futuristic plan for "developing all of Mercury to the end" was seenand in our official scandalous press and on Popular Mechanics.
Classification of types of structures The
so-called I type of the Dyson sphere is not a continuous conventional sphere - Roy Dyson (Dayson Swarm) - from separate, in no way among themselves unrelated elements moving in their stable orbits, at a more or less constant distance from the central star. Orbits are regulated by any engines on the elements themselves.
The so-called Type II Dyson Spherethis is not a solid conventional sphere of individual unrelated elements, soaring at a constant distance from the central body due to the balance of the force of attraction and the force of pressure of the light / solar wind. The elements are called statites (such as stable satellites). The balance of these forces (attraction and pressure of light) is achievable only with a very light material: with a very light strong shell: 0.78 grams per m2, which is unattainable for modern technologies.
The so-called Type III Dyson Spherethis is a simple and continuous sphere in the form of a light balloon, the so-called “Dyson Bubble”. The balance of forces is based on the equality of the pressure of light by gravity, like type II, but with a continuous shell, very light and thin: 0.78 grams per m2, which is unattainable for modern technologies - for such a sphere with a radius of 1 AU. enough material weighing one large asteroid Pallas: 2.17 per 10 ^ 20 kg.
Rejecting the II and III type of the Dyson sphere due to the lack of similar materials at the moment (and in the foreseeable future), we again come to the Dyson swarm - to the sphere of the I type, simply because it is more real than all the other types .
There are other, exotic types of structures (for example, here ), but they are all even more complicated and unreal.
Dyson Sphere begins with the Ring
Consider the process of creating the Dyson Sphere, or rather Roy Dyson in the form of a Ring.
Where does the technical civilization begin the installation of any sphere of Dyson? With the withdrawal of individual elements of the sphere into orbit. Only elements of the Dyson sphere, moving in a stable circular orbit with the desired radius, can be assembled together (without a rigid connection, with gaps) to gradually form step by step ... alas, not a sphere, but only a ring, since the higher or lower the element above the plane of the ring, the more difficult it is to put it into a stable orbit that does not intersect the ring that has already been created and is not very far from it radially. Although there are estimates how to make a lot of individual non-intersecting orbits for the elements. For example, a beautiful version with different ascending orbit nodes and pericenter (but with the same inclination and radius) is Roy’s variant with the maximum number of individual orbits in the form of a “laced” torus calledJenkins Swarm (Roy Jenkins) is used for the image on the cover of this article.
Installation is likely to begin with the assembly of a part of the Dyson ring in the ecliptic plane. After all, outside the plane of the ecliptic there are fewer asteroids and other material for creating ring elements. And in the plane of the ecliptic and more material, it is easier to deliver this material to the desired radius, and it is easier to give it (or an already constructed element of the ring) the desired orbital speed. We call such a non-rigid construction of separate closely-located elements of the swarm the Dyson Ring (since the Ring of Niven is by definition necessarily rigid).
After creating a flexible (consisting of unrelated or weakly connected elements) rings of a given radius, with the accumulation of experience and improvement of technology, civilization can create other rings, already across the plane of the ecliptic and at an angle to it, but these rings should be markedly enlarged or reduced radius, so as not to touch the original ring.
This is all in the first part of the article: the history of the idea was briefly reviewed and the optimally feasible version of the Dyson sphere was selected.
In the second part of the articleThe construction of the Dyson Ring based on a swarm of standard, autonomous elements is considered. The parameters of such a Ring are calculated for the Solar System with two variants of the location of the Ring: to the Earth's orbit (beyond the orbit of Venus, closer to the Sun) and beyond the Earth's orbit (to the orbit of Mars). The standard element of such a Ring, its geometric and weight parameters and possible functions are also considered in detail.
In the third part of the article , the purpose of constructing such a Ring, methods of its use and methods of non-standard use of individual autonomous elements of the Ring outside the orbit of the Ring are revealed. It also discusses the problem of finding such a giant structure from the outside.
Freeman Dyson himself admitted that he was inspired by the idea of the science fiction novel The Star Maker, Olaf Stapledon, whose author Olaf Stapledon described a similar structure (rings around stars without planets and new artificial planets) as early as 1937.
')
But Olaf Stapledon could borrow the idea from another author: John Desmond Bernal (JD Bernal, “The World, the Flesh, and the Devil”) in the article “Peace, Flesh and the Devil” described spherical space colonies built of thin shells around transferred to new orbits of asteroids. He also implicitly hinted that when there are many such colonies, then they will intercept most of the energy of our luminary.
The founder of cosmonautics, our compatriot Konstantin Eduardovich Tsiolkovsky, also offered habitable space colonies, not in the form of a sphere, but in the form of a pyramid or cone, deployed with a transparent base towards the Sun (with plants and inhabitants located on the walls of the cone) - the so-called “ethereal cities". And here the scope of Dyson? And despite the fact that in the picture below from Tsiolkovsky’s diary it is clear that he depicted these cones precisely combined into an ordered network (what is not a part of the Dyson sphere?) With the help of certain beams or cables passing through the centers of these objects (bottom left):
In addition to these authors, American science fiction writer Raymond Z. Gallun also expounded something similar.
Even in the Middle Ages (15th century), the Italian thinker of the 15th century, Marsilio Ficino , foreseeing human capabilities in the future (intuitively feeling that human capabilities are developing on the basis of knowledge, that is, accurate human knowledge of the laws of nature), completely self-confident (for its time) wrote:
Man measures the earth and the sky ... Neither the sky seems too high for him, nor the center of the earth too deep ... And since man knew the structure of the heavenly bodies, then who would deny that man’s genius is almost the same as that of the creator of the heavenly bodies, and that he could create these luminaries in some way if he had instruments and heavenly material .Striking words, as if foreshadowing the daring of future space explorers! - notes Lev Lyubimov, the author of that book on art (and it turns out they write about astronomy!), Where I read these lines (“The sky is not too high” - the golden age of Italian painting, the series “In the world of beauty”, Lev Lyubimov, Moscow, Children's literature , 1979 ).
It should be noted that although the Dyson sphere is not an analogue of a star — a star or a planet, but in some sense it uses the first and replaces the second. The Dyson sphere can be understood not only a sphere, but any construction. The main thing is that this construction should be large-scale and intercept a significant part of the Sun's radiation (and not thousandths of a percent, as existing in our planet system). Of course, the Italian Marsilio Ficino in the 15th century could not invent the concept of the Dyson sphere (he lacked knowledge) and simply dreamed of creating a semblance of natural celestial bodies, but nevertheless he was able to identify in his short text three of the four main problems of creating a sphere by civilization Dyson:
1. The method of creation - in what way can one create a sphere with a radius of 50-250 million kilometers?
2. Means of creation - with what “ tools ” can one create such a sphere so as not to harm oneself and one’s entire system?
3. The material for the creation is the very " heavenly material " that determines by its presence, quantity and quality the very possibility of creating such a sphere (as well as the methods and speed of construction).
4. Location - which needs to be determined in advance, before construction, so that later it does not turn out that having a sphere in this place only complicates the life of a civilization or is simply dangerous for its system.
Let's start with the last problem - from the location of the sphere, since this is the most important decision, which significantly influences subsequent ones. And the answer to the question about the placement of the sphere directly depends on the purpose of the sphere.
Classification by location
Option A: If we need the Dyson sphere simply to obtain the maximum energy from the Sun (without taking into account the preservation of planetary illumination, especially the illumination of the Earth), then it would be more logical to arrange the sphere as close as possible to the Sun.
Three main problems arise:
- The problem of gravitational stability and stability - the sphere should not fall on the Sun, break or deform from the gravity of the Sun, as well as from the gravity of the nearest planets (Mercury and Venus).
- The problem of cooling the sphere - the sphere should not melt or deform from the energy of the sun.
- If the cooling problem is solved, then the problem of mass transfer from the Sun to the sphere remains - the solar wind and coronary emissions will reach the surface of the sphere, damage it, settle on it, make it heavier and charge it.
Option B: If we need a sphere as a habitat surface for people (with all the necessary infrastructure, atmosphere, soil, plants and animals), then the sphere should be solid and located where the light of the Sun has about the same intensity as on the surface of the Earth - those. at a distance of the Earth's orbit or even further (to compensate for the absence or weakness of the atmosphere, the magnetosphere, necessary for protection from solar radiation).
Three new main problems arise (the above problems of Option A do not disappear, but go to the background):
- Stability - the sphere should not touch the orbits of other planets (for example, the Earth), should not be strongly attracted by them. Therefore, it should be far beyond the orbit of the Earth (30-50 million km or 0.2-0.3 AU).
- The strength and thickness of the sphere - the question is whether the surface of the sphere is strong enough: in addition to technology, this is largely determined by the composition and quality of the material of the Solar System.
- The presence of the material - if it is not enough, then to build such a sphere does not make sense.
Option B: If we need a sphere with a thin primitive (easily repaired) surface intercepting light from the Sun, but not necessarily solid (withstanding the soil, people), but with a maximum surface area and with minimal energy flow (so as not to worry about overheating the sphere) , the sphere should be located somewhere further away from the luminary.
For such a sphere, three main problems are also relevant (other problems are less important):
- The presence of material - for such a huge sphere it may not be enough.
- Stability of the sphere - remains a problem, but not so urgent.
- Collisions with asteroids, comets, etc. - the problem is more serious than for the previously described options, since the surface of such a sphere per day is crossed by many more small celestial bodies.
Classification by purpose
From a cursory examination of the location of the Dyson sphere, it is clear that much is also determined by the purpose of the sphere:
Assignment 1: Strong Energy Cocoon around a Star
As close as possible to the star, a rotating (not necessarily solid) durable cooled shell is created with catchers (as well as transducers and radiators) of energy - in order to obtain maximum energy with minimum construction volumes. How close to the sun can you build such a sphere? If we take the sun to warm up to 1000 K (without special cooling), then the radius will be about 23 million km, which lies inside Mercury's orbit (radius of its orbit is from 40 to 60 million km) - these calculations are taken from the list of answers to typical questions on the Dyson Sphere .
All received light energy is converted into another (for example, into electrical energy) and then either transferred somewhere (for example, by laser or radio wave), or applied on site. The state, light, stability of the orbits of the planets and even their very existence are not taken into account - if necessary, they are sorted into materials for creating a sphere.
Despite some extremes of this purpose of the sphere (the instability of the sphere must be constantly parried by the release of gases / solar wind from different directions, or by the operation of engines on the outer / inner shell of the sphere) and the problem of strength (for our development level, the main problem is the strength of any modern materials) It is fully justified for high level civilizations. Especially if such a way is mastered not by its own luminary, but by an alien star. This is not the cradle of civilization, where a hand will not rise (or out of respect for the history of its world), apart from disrupting the stability of the orbits of other planets when disassembling even one planet. If such an alien star has an unfortunate (from the point of view of civilization) spectrum, does not have planets suitable for exploration and dwelling, then no one will particularly regret such a system with a star: the planets will go to create a sphere.
The design of this type is especially optimal for white dwarfs : these inactive, slowly (billions of years) cooling stars remain shining steadily: their surface temperature cools at an average speed of about 10,000 K over 1 billion years - this estimate is based on the temperature difference of a new white dwarf: from 90 000 K (estimated by absorption lines) or 130 000 K (estimated by X-ray spectrum), to temperatures below 4000 K (the so-called black dwarf) for some white dwarfs, cooled over 13 billion years (the lifetime of the Universe). White dwarfs shine without flares and coronary mass emissions, they are small in size and luminosity - around them you can make a sphere with a radius ten times smaller (even less than 1 million km) than around the active Sun or other stars of similar size. But the problem of the strength of the sphere remains.
In 2015, two Turkish scientists calculated the radii of Dyson spheres (suitable for people to live on an external solid surface at room temperature) for different types of white dwarfs. The results are in the range of 2-5 million km, and the amount of material to create such spheres with a shell thickness of about 1 m is approximately equal to the material of the entire Moon. This work was noticed both in the USA and in our media .
Dealing with red dwarfs is a bit more complicated: they often have flares, their hard radiation is more dangerous than solar radiation. But they also have their advantages: there are many of them, and their weight is from 30% and up to 8% by weight of the Sun, considerably smaller luminosity values and small geometrical dimensions allow building spheres with a radius smaller than for the Sun, and the duration of their life is far away. overlaps both the life expectancy of the Sun and the cooling time of white dwarfs to a level when the sphere gains little energy.
Conclusion: This assignment of the Dyson sphere makes sense for certain types of small stars, but clearly not for the native system of civilization and not for the first attempt of any civilization to build the Dyson sphere. That's when civilization comes out into stellar spaces, then it will begin to “extinguish” the nearest stars (especially dwarfs) with such cocoons, thereby forming the Fermi bubble without stars in the sky (Richard Carrigan's term). In the optical range, it will look like stars in a nebula, but at the same time decently glowing in the IR range. The name “Fermi bubble” was suggested due to the fact that such a group of Dyson spheres will gradually expand in accordance with the assumption of Enrico Fermi about the rate of expansion of the range of such civilizations in 0.001-0.01 from the speed of light.
Appointment 2: A huge surface for the settlement of people
The most ambitious, difficult to create and financially expensive assignment for the Dyson sphere. Requires a truly huge amount of materials and resources to create. If we do not consider it possible to disassemble the Earth or darken it, then the radius of such a sphere should be about 190-250 million km (40-50 million km beyond Earth's orbit to reduce the mutual influence of the sphere and the Earth).
In connection with simple conclusions from physical laws (Gauss's Law) - the so-called Newton's theorem on the absence of gravity inside spherical bodies (in English: Shell theorem) - for any uniformly dense spherical shell, gravity inside the shell depends only on the mass inside (but not on mass of the shell itself). Therefore, it will be simply dangerous for people to be on the inner surface of such a shell: they will be attracted inward to the Sun, and not to the shell (no matter how thick it is). In connection with this, some originals even suggest settling on the outer shell of such a sphere ! (and the above mentioned work on white dwarfs ). It is possible to get rid of falling inwards: by twisting the sphere to the normal orbital speed for such a radius, which will add about 1/3 of the earth's gravitational force outward.
But the atmosphere will not be particularly confined (it must be protected from the internal vacuum), all the light from the Sun will re-reflect from the shell and blind from all sides, and the solar wind closed inside the sphere with an intensity of about 2.5 per 10 ^ 12 ions per square meter for a second can not go anywhere.
The main problem is different: it is necessary to achieve a considerable strength of the shell of this sphere so that the sphere does not fall inward towards the Sun under the action of the gravity of the Sun. For a non-rotating sphere, a certain strength is required to withstand the pressure caused by the attraction of the Sun to the test kilogram of the sphere material, which is equal to (calculations from here ):
Fin = G * M * m / R ^ 2 [kg * m / sec ^ 2]
where G = 6.674 * 10 ^ -11 [m ^ 3 / (kg * s ^ 2)] is the gravity constant,
M = 2 * 10 ^ 30 kg is the mass of the Sun,
m = 1 kg is the test mass per unit area of the sphere, and R is the radius of the sphere 190 million km
= 6.674 * 1.9885 * 10 ^ (30 - 11) / 190 * 10 ^ 9 * 190 * 10 ^ 9 = 3.6768 * 10 ^ 19/10 ^ 22 = 3.68 * 10 ^ -5 [kg * m / s ^ 2] = 0.04 millinewton.
This is like nonsense, some tiny fraction of the force of gravity on Earth (9.8 Newtons act on the test kilogram on the surface of our planet). But the problem is that the weight of all the other kilograms that make up the sectors of the dome of the sphere from below and from above (see the graphic drawing below) presses on this kilogram of the shell.
Yes, their weight at such a distance from the Sun is minimal, the same 0.04 millinewton, but this meager force must be multiplied vectorially by the millions of these kilograms that make up the mass of the dome sector. The resulting force depends on the thickness of the shell and even for centimeter thicknesses it is simply terrible (since the size and mass of the sector of the dome is huge).
If you create a rotating sphere (when assembling a sphere from elements, this is the only way to start: all elements of the equatorial ring must first be placed into a stable orbit, which requires rotation around the star at speeds close to the orbital speeds of the planets: 30 km / s for Earth or about 25 km / s for the orbit behind the earth, but before the Martian), then this rotation will help the assembled rigid shell of the sphere only at the equator and next to it. There, centrifugal acceleration (inertial force) is:
Fout = m * V ^ 2 / R [kg * m ^ 2 / m * sec ^ 2]
= 25 * 25 * 10 ^ 6/200 000 000 = 625/200 = 3.125 [kg * m / s ^ 2] = 3.1 Newton (3 times less than the earth's weight).
But this acceleration does not reduce the force of attraction to the luminary at the poles of such a sphere, and does not particularly help at middle latitudes. The problem with the pressure of a huge mass of sectors of the upper and lower domes on the rapidly rotating equator of the sphere remains. The problem of lack of resources remains: the scientist Anders Sandberg estimates that there is 1.82 x 10 ^ 26 kg of easily used building material in our Solar System, which is sufficient for building a Dyson shell with a radius of 1 AU, an average weight of 600 kg / m2 with a thickness of approximately 8-20 cm, depending on the density of the material. If one throws out the material of the core of gas giants, which, to put it mildly, are difficult to access, then the inner planets alone can provide only 11.79x10 ^ 24 kg of substance, which is enough to build a Dyson shell with a radius of 1 AU. with a mass of only 42 kg / m2 and about a centimeter thickness.
Conclusion: This assignment of the Dyson sphere only makes sense for idealistic dreams of the power of civilization. Modern materials do not allow to create such a sphere. In addition, no material and no new technologies will change the fact that the inner surface of the sphere is not suitable for living in its pure form (we also need an internal transparent sphere to keep the atmosphere from falling down towards the luminary), and the sphere itself is dangerously unstable. And most importantly: the material in our system is simply not enough.
Assignment 3: Light Star Energy Concentrators
Such spheres can be both farther and closer to the Earth's orbit. The main thing is that their purpose is not to live the maximum number of people on their inner surface, but to use the energy radiated by the Sun, if not 100% of this energy. These assumptions according to purpose open up wide possibilities in terms of forms and types of structures.You can choose the one that is available to current technologies, without threatening the unreal. For example, you can move away from the sphere to the individual elements that make up the so-called Roy Dyson, in orbit around the Sun (in Mercury) , which receive and process energy and send it further to consumers.
Elements with no energy conversion that simply send reflected sunlight in the right direction (mentioned here ) can also be considered . A set of such non-rigid rings (of swarm elements) with different radii and angles to the ecliptic plane can, in principle, intercept even more than 50% of solar radiation, even if the rings are not solid (not rigid) and there are gaps between the rings themselves.
Yes, this is not a sphere in the geometric sense of the word, but a completely practical alternative to the sphere. The main thing is to abandon the sphere itself - as they say: do you need to get there or do you need to get there?
Conclusion:This vague assignment of the Dyson sphere gives greater flexibility to the whole concept and allows us to consider several shapes and types of structures, with different initial tasks and with different results, as well as with different potentials for improvement and modernization.
The futurist Stuart Armstrong came to the same conclusion, choosing Roy Dyson (Dayson Swarm) as a natural perspective for civilization, built from Mercury material and located approximately in its orbit: see the same video above (from 2:50 to 4:50) in English, with arguments about the development of hematite (chemical formula Fe2O3) on Mercury, about reflectors and collectors of light. This futuristic plan for "developing all of Mercury to the end" was seenand in our official scandalous press and on Popular Mechanics.
Classification of types of structures The
so-called I type of the Dyson sphere is not a continuous conventional sphere - Roy Dyson (Dayson Swarm) - from separate, in no way among themselves unrelated elements moving in their stable orbits, at a more or less constant distance from the central star. Orbits are regulated by any engines on the elements themselves.
The so-called Type II Dyson Spherethis is not a solid conventional sphere of individual unrelated elements, soaring at a constant distance from the central body due to the balance of the force of attraction and the force of pressure of the light / solar wind. The elements are called statites (such as stable satellites). The balance of these forces (attraction and pressure of light) is achievable only with a very light material: with a very light strong shell: 0.78 grams per m2, which is unattainable for modern technologies.
The so-called Type III Dyson Spherethis is a simple and continuous sphere in the form of a light balloon, the so-called “Dyson Bubble”. The balance of forces is based on the equality of the pressure of light by gravity, like type II, but with a continuous shell, very light and thin: 0.78 grams per m2, which is unattainable for modern technologies - for such a sphere with a radius of 1 AU. enough material weighing one large asteroid Pallas: 2.17 per 10 ^ 20 kg.
Rejecting the II and III type of the Dyson sphere due to the lack of similar materials at the moment (and in the foreseeable future), we again come to the Dyson swarm - to the sphere of the I type, simply because it is more real than all the other types .
There are other, exotic types of structures (for example, here ), but they are all even more complicated and unreal.
Dyson Sphere begins with the Ring
Consider the process of creating the Dyson Sphere, or rather Roy Dyson in the form of a Ring.
Where does the technical civilization begin the installation of any sphere of Dyson? With the withdrawal of individual elements of the sphere into orbit. Only elements of the Dyson sphere, moving in a stable circular orbit with the desired radius, can be assembled together (without a rigid connection, with gaps) to gradually form step by step ... alas, not a sphere, but only a ring, since the higher or lower the element above the plane of the ring, the more difficult it is to put it into a stable orbit that does not intersect the ring that has already been created and is not very far from it radially. Although there are estimates how to make a lot of individual non-intersecting orbits for the elements. For example, a beautiful version with different ascending orbit nodes and pericenter (but with the same inclination and radius) is Roy’s variant with the maximum number of individual orbits in the form of a “laced” torus calledJenkins Swarm (Roy Jenkins) is used for the image on the cover of this article.
Installation is likely to begin with the assembly of a part of the Dyson ring in the ecliptic plane. After all, outside the plane of the ecliptic there are fewer asteroids and other material for creating ring elements. And in the plane of the ecliptic and more material, it is easier to deliver this material to the desired radius, and it is easier to give it (or an already constructed element of the ring) the desired orbital speed. We call such a non-rigid construction of separate closely-located elements of the swarm the Dyson Ring (since the Ring of Niven is by definition necessarily rigid).
After creating a flexible (consisting of unrelated or weakly connected elements) rings of a given radius, with the accumulation of experience and improvement of technology, civilization can create other rings, already across the plane of the ecliptic and at an angle to it, but these rings should be markedly enlarged or reduced radius, so as not to touch the original ring.
This is all in the first part of the article: the history of the idea was briefly reviewed and the optimally feasible version of the Dyson sphere was selected.
In the second part of the articleThe construction of the Dyson Ring based on a swarm of standard, autonomous elements is considered. The parameters of such a Ring are calculated for the Solar System with two variants of the location of the Ring: to the Earth's orbit (beyond the orbit of Venus, closer to the Sun) and beyond the Earth's orbit (to the orbit of Mars). The standard element of such a Ring, its geometric and weight parameters and possible functions are also considered in detail.
In the third part of the article , the purpose of constructing such a Ring, methods of its use and methods of non-standard use of individual autonomous elements of the Ring outside the orbit of the Ring are revealed. It also discusses the problem of finding such a giant structure from the outside.
Source: https://habr.com/ru/post/397719/
All Articles