The A Dyson sphere is a hypothetical megastructure that actually covers the star and captures most of its power output. The concept is a mind experiment that tries to explain how a space civilization will meet its energy needs once that requirement goes beyond what can be derived from the planet's own home resources. Only a fraction of the star's energy emissions reach the surface of an orbiting planet. The structure of buildings that surround the star will allow civilization to harvest far more energy.
The first contemporary description of the structure is by Olaf Stapledon in his science fiction novel Star Maker (1937), in which he describes "every solar system... surrounded by a screen of light, focused, escape for intelligent use. "The concept was later popularized by Freeman Dyson in his 1960 paper" Find Artificial Stellar Source from Infrared Radiation ". Dyson speculates that such a structure would be a logical consequence of the increasing energy demand of technological civilization and would be a necessity for its long-term survival. He proposed that the search for such structures could lead to an advanced and intelligent detection of extraterrestrial life. The various types of Dyson balls and its ability to harvest energy will correspond to the rate of technological advancement on the Kardashev scale.
Since then, other variant designs involving the construction of artificial structures or a series of structures to cover the star have been proposed in exploratory techniques or described in science fiction under the name "Dyson sphere". These proposals have not been limited to solar power stations, with many involving residential or industrial elements. Most fictitious depictions depict a dense shell of matter that surrounds the star, considered the most unreasonable variant of the idea. In May 2013, at the Century Bank Century Century Symposium in San Diego, Dyson repeated his comments that he hoped the concept was not named after him.
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The Dyson scope concept is the result of a mind experiment by physicist and mathematician Freeman Dyson, as he theorizes that all technological civilizations are constantly increasing their energy demand. He reasoned that if human civilization expands energy demand long enough, there will come a time when it demands total solar energy output. He proposed an orbiting structural system (which he originally referred to as shell ) designed to cut and collect all the energy produced by the Sun. Dyson's proposal did not specify how such a system would be built, but focused solely on the issue of energy collection, on the basis that such structures could be distinguished by an unusual emission spectrum compared to stars. His 1960 paper "Find Stellar Source Made Infrared Infra-Red Radiation", published in the journal Science, was credited with being the first to formalize the concept of the Dyson sphere.
However, Dyson is not the first to advance this idea. He was inspired by the mention of the concept in 1937 Star Macer science fiction novel by Olaf Stapledon, and possibly by the works of JD Bernal, Raymond Z. Gallun, and Edgar Rice Burroughs, who seem to have explored similar concepts in their work.
Maps Dyson sphere
Feasibility
Although such megastructures may be theoretically possible, all plans to build the Dyson sphere remain in place today far beyond human engineering capacity. The amount of craft required to acquire, deliver, and maintain a complete Dyson ball far exceeds the industry's current capabilities. George Dvorsky has advocated the use of self-replicating robots to overcome this limitation in a relatively short time. Some people claim that such a habitat can be built around white dwarves and even pulsars.
Variant
In fictional stories, the Dyson-sphere concept is often interpreted as an artificial matter scope around stars. This perception is based on a literal interpretation of Dyson's original short paper which introduces the concept. Responding to the letters requested by some papers, Dyson replied, "The hard shell or ring around the star is mechanically impossible.The" biosphere "shape I imagine consists of a loose collection or a bunch of objects moving in independent orbits around a star."
Dyson swarm
The closest variant to Dyson's original conception is "Dyson swarm". It consists of a large number of independent constructions (usually solar satellites and habitat spaces) that orbit in dense formations around stars. This construction approach has advantages: the components can be of the right size, and can be gradually constructed. Various forms of wireless energy transfer can be used to transfer energy between swarm and planetary components.
The disadvantages resulting from the orbital mechanical properties will make the orbital arrangements of the hordes very complex. The simplest setting is the Dyson ring, in which all such structures have the same orbit. More complex patterns with more rings will cut more star output, but will result in some constructs that interfere with others periodically when their orbits overlap. Another potential problem is the increased loss of orbital stability when adding more elements increases the likelihood of orbital disturbance.
As noted below, such collector clouds will alter the light emitted by the star system. However, the disruption compared to the overall natural spectrum emitted is likely to be too small for Earth-based astronomers to observe.
Dyson Bubble
The second type of Dyson ball is "Dyson bubble". It will be similar to a bunch of Dyson, made up of many independent constructions and can also be built gradually.
Unlike the Dyson herd, the constructs that compose it are not in orbit around the star, but will become statites - satellites suspended by using a very large light screen using radiation pressure to resist the star's gravitational pull. Such constructions will not be in danger of collision or interfere with each other; they will be completely silent towards the star, and independent of each other. Since the ratio of the radiation pressure to the force of gravity of a star is constant regardless of its distance (provided that the statite has an unobstructed view line to its star surface), the statites can also vary the distance from the center. star.
The practicality of this approach is questioned by modern material science, but it can not be ruled out. The 100% reflective statute that is deployed around the Sun will have an overall density of 0.78 grams per square meter display. To illustrate the low mass of the required material, consider that the total mass of a material bubble such as 1 AU in a radius will be about 2.17 ÃÆ' - 10 20 kg, which has the same mass as the Pallas asteroid. Another illustration: Plain paper has a density of about 80 g/m 2 .
Such material has not been produced in the form of a working light screen. The lightweight carbon light light material currently produced has a density - no charge - 3 g/m 2 , or about four times the weight needed to build a solar statite.
One sheet of graphene, a two-dimensional carbon form, has a density of only 0.37Ã, mg per square meter, making such a single sheet of graphene possibly effective as a sun screen. However, in 2015 graphene has not been made in large sheets, and has a relatively high level of radiation absorption, about 2.3% (ie, still about 97.7% will be transmitted). For frequencies at upper GHz and lower THz ranges, absorption rates are as high as 50-100% due to voltage bias and/or doping.
The ultra-light carbon nanotubes coupled through molecular-making techniques have a density of between 1.3 g/m 2 to 1.4 g/m 2 . By the time civilizations are ready to use this technology, the carbon nanotube manufacturing may be optimized enough so that they have a density lower than 0.7 g/m 2 , and the average screen density with rigging may be stored up to 0.3 g/m 2 (the "stabilizer stabilization" light screen requires minimal additional mass in the rigging). If such a screen could be built in the density of this area, a cylindrical space habitat of O'Neill proposed by the L5 Society - 500 km 2 , with space for over 1 million inhabitants, mass 3 ÃÆ' - 10 6 ton - can be powered by a 3,000 km circular light screen, with a combined mass of sails/habitats 5.4 ÃÆ' - 10 9 kg. In comparison, this is only slightly smaller than the diameter of Jupiter Europa's moon (though the screen is a flat disc, not a ball), or the distance between San Francisco and Kansas City. However, such structures have much less mass than asteroids. Although the construction of a large habitable statite will be a big job, and the necessary material science behind it is the initial stage, there are other engineering achievements and the necessary materials proposed in other Dyson ball variants.
In theory, if enough satellites were created and spread around their stars, they would compile a non-rigid version of the Dyson shell mentioned below. Such shells will not suffer from the great compressive pressure weakness, as does the mass requirement of such shells as high as rigid forms. As the shell will, however, have the same optical and thermal properties as a rigid form, and will be detected by seekers in the same way (see below).
Dyson shell
The Dyson ball variant most often depicted in fiction is the "Dyson shell": a dense shell of material uniform around the star. Such a structure would completely change emissions from the central star, and would cut 100% of the star's energy output. Such structures will also provide a very large surface that many imagined would be used for shelter, if the surface could be made habitable.
The ball sphere of Dyson ball in the Solar System with a radius of one astronomical unit, so that the interior surface will receive the same amount of sunlight as the Earth per unit of solid angle will have a surface area of ​​about 2.8 ÃÆ'â € <10 < soup> 17 Ã, km 2 (1,1 ÃÆ' - 10 17 sq sq mi), or about 550 million times Earth's surface area. It will intercept 384.6 full yottawatts (3,846 ÃÆ'â € "10 26 watt) from the Sun's output. The non-shell design will cut less, but the shell variant represents the maximum energy that may be captured for the Solar System at the point of evolution of the Sun. This is about 33 trillion times the consumption of human power in 1998, which is 12 terawatt.
There are some serious theoretical difficulties with Dyson's dense ball shell variant:
Such shells will not have a net gravitational interaction with a twisted star (see shell theorem), and may drift with respect to the central star. If such movements are not corrected, they can eventually produce a collision between the ball and the star - most likely with poor results. Such a structure would require one form of propulsion to counter any irregularities, or a way to repel the surface of the ball away from the star.
For the same reason, such shells will not have a net gravitational interaction with others in them. The contents of any biosphere placed on the inner surface of the Dyson shell will not be attracted to the surface of the ball and will only fall to the star. It has been proposed that the biosphere can be contained between two concentric balls, placed on the inside of a spinning ball (in this case, the artificial force "gravity" is perpendicular to the axis of rotation, causing all matter to be placed on the interior from the ball to the pool around the equator, effectively making the Niven ring ball for the purpose of residence, but still fully effective as a collector of radiation energy) or placed outside the ball where it will be held in place by the star of gravity. In such cases, some form of illumination must be made, or balls made at least partially transparent, since the starlight otherwise would be completely hidden.
If the assumption of a radius of AU, then the compressive strength of the material that forms the ball must be very large to prevent explosions due to star gravity. Any point chosen at random on the surface of the sphere can be seen under the basic pressure of the 1 AU dome at the height below the Sun's gravity at that distance. Indeed, it can be seen as being at the base of an infinitely chosen dome, but since most of the forces of the dome are mutually opposed by others, the total force at that point is very large, but limited. No matter is known or theorized strongly enough to withstand this pressure, and form a rigid static ball around the star. This has been proposed by Paul Birch (in relation to the smaller "Supra-Jupiter" construction around larger planets rather than stars) allowing to support the Dyson shell in a dynamic manner similar to that used in space fountains. The mass that runs on a circular track on the inside of the ball, at speeds significantly greater than the orbital velocity, will squeeze out on the magnetic pads due to centrifugal force. For a Dyson shell of a 1-AU radius around a star of the same mass as the Sun, a mass traveling ten times the orbital speed (297.9 km/s) would support 99 (a = v 2 /r) multiplied by its own mass in an additional shell structure.
Also if the assumption of a radius of AU, then there may not be enough building materials in the Solar System to build a Dyson shell. Anders Sandberg estimates that there are 1,82 ÃÆ' - 10 26 kg of easy-to-use building materials in the Solar System, enough for a 1-AU shell with mass of 600 kg/m 2 - about 8-20 cm of average thickness, depending on material density. These include giant gas cores that are difficult to access; inner planets only provide 11.79 ÃÆ' - 10 24 kg, enough for a 1-AU shell with a mass of just 42 kg/m 2 .
The shells will be susceptible to the impact of interstellar bodies, such as comets, meteoroids, and materials in interstellar space that are currently being deflected by the shock of the Sun's bow. The heliosphere, and any protection that theoretically provides, will cease to exist.
Other types
Dyson net
Another possibility is "Dyson net", a cable network that is strung about stars that can have power or heat collection units strung together between cables. The Dyson net reduces to special cases of Dyson shells or bubbles, however, depending on how the wires are supported against the sun's gravity.
Bubbleworld
Bubbleworld is an artificial construction consisting of a living space shell around a hydrogen gas ball. Air-filled shells, people, houses, furniture, etc. The idea was structured to answer the question, "What is the largest space colony that can be built?" However, most of the volume is uninhabitable and there is no power source.
Theoretically, any gas giant could be flanked by a solid shell; on a certain radius the surface gravity will be terrestrial, and energy can be provided by tapping the planet's thermal energy. This concept is explored peripherally in the Accelerando novel (and the Curator's short story, inserted into the novel as chapter) by Charles Stross, where Saturn is transformed into a human-inhabited world.
Stellar Machine
The Stellar engine is a hypothetical class of megastructures whose purpose is to extract useful energy from stars, sometimes for specific purposes. For example, Matrioshka's brain extracts energy for computing purposes; Shkadov pusher extracts energy for propulsion purposes. Some of the proposed star machine designs are based on the Dyson scope.
Black holes can be a source of electricity rather than a star to improve the efficiency of material-to-energy conversion. Black holes are also smaller than stars. This will reduce the communication distance that is important to the computer-based community as described above.
Search for megastructures
In Dyson's original paper, he speculates that advanced extraterrestrial civilizations are likely to follow the same pattern of power consumption as humans, and eventually build their own collector sphere. Building such a system would create civilization like Type II Kardashev civilization.
The existence of such a collector system would alter the light emitted from the star system. The collector will absorb and radiate energy from the star. The wavelength of the radiation emitted by the collector will be determined by the emission spectrum of the substances that make up it, and the collector temperature. Because it seems highly likely that these collectors will consist of heavy elements not normally found in their central star emission spectrum - or at least emit light on relatively "low" energies compared to what they would emit as energetic. the free nucleus in the star's atmosphere - there will be atypical wavelengths of light for this type of star spectrum in the light spectrum emitted by the star system. If the percentage of star output filtered or transformed by absorption and irradiation is significant, it can be detected at the interstellar distance.
Given the amount of energy available per square meter at a distance of 1 AU from the Sun, it is possible to calculate that the most known substance will irradiate energy in the infrared portion of the electromagnetic spectrum. Thus, the sphere of Dyson, constructed by a form of life no different from that of humans, who dwell close to a Sun-like star, made with material similar to that available to humans, is likely to cause an increase in the amount of infrared radiation in the emitted spectrum of the star system. Therefore, Dyson chose the title "Find Stellar Source Artificial Radiation Infrared" for his published paper.
SETI has used this assumption in their search, looking for the "heavy infrared" spectrum of the solar analogs. In 2005 Fermilab had an ongoing survey for the spectra by analyzing data from Infrared Astronomical Satellite (IRAS). Identifying one of the many infrared sources as Dyson's scope will require enhanced techniques to distinguish between Dyson's scope and natural sources. Fermilab found 17 potential "ambiguous" candidates, four of whom have been named "funny but questionable". Other searches also produced some candidates, which, however, have not been confirmed.
Postulated Skills
On October 14, 2015, the realization of the strange pattern of light from KIC 8462852 star, dubbed "Tabby's Star" after Tabetha S. Boyajian - the main researcher who discovered irregular light fluctuations - was captured by the Kepler Space Telescope, raising speculation that a Dyson ball might have been found. In February 2016, Boyajian gave a TED lecture in which he explained the story of how his research on the star quickly became mysterious. However, he is skeptical and in talks he reminds everyone that skepticism is the best policy every time to investigate foreign territory. The exact quote is as follows:
"Extraordinary claims require extraordinary evidence, and it is my job, my responsibility, as an astronomer to remind people that the alien hypothesis should always be the last resort."
Wanting to understand the strange light patterns, Tabetha S. Boyajian made several hypotheses to test. The first general assumption is an exoplanet that transits its massive star, but the decline in light lasts between 5 and 80 days and is irregularly separated, thus setting aside any kind of orbit for a celestial object. Dust clouds are proposed but the star shows no signs of being young so a dust cloud is highly unlikely. Finally, the comet rain is hypothesized. However, as Boyajian pointed out in his TED, it is also highly unlikely. "It took hundreds of comets to reproduce what we observed, and this is just a comet that passes between us and the stars, and in fact, we're talking thousands to tens of thousands of comets."
So after all the natural explanations became weak, his team decided to send their research to SETI (Searching for life in space) to rule out alien structures. After reviewing the research, the SETI Institute was so interested that they decided to study the star itself and direct their Allen Telescope Array (ATA) on the star "in hopes of capturing a signal that could reveal technological civilization."
The SETI Institute mentions that what interests them is that "the current dip time (in light) indicates that whatever this material is, it lies at the exact distance from the star to be in a habitable zone, where we believe life as we are can grow like the one on Earth. "
Feeling skeptical of Boyajian, he finally decides to take a SETI approach and let himself have some fun in hypothesizing what light patterns can happen. In Ted Talk, he joked: "Another favorite idea I have is that we have just witnessed the interplanetary spacecraft battle and the devastation of the planet that devastated the disaster, and now I recognize that this will produce a lot of dust we do not have." "But if we had asked the aliens in this explanation, then who said they did not efficiently clean up all this mess for recycling purposes?" The search for answers to KIC 8462852 is still ongoing.
On August 25, 2016, a similar phenomenon was reported for other star objects: EPIC 204278916, a young pre-M-type pre-sequence star with completed disks. Dimensions of up to 65% for 25 consecutive days (out of a total of 79 observations) were observed. Variability is very periodic and is associated with star rotation. The researchers hypothesize that irregular dimming is caused by either a distorted disc edge or a comet-like object that passes in a circular or eccentric orbit.
Fiction
As mentioned above, the Dyson ball is derived from fiction, and it is a concept that has often appeared in science fiction ever since. In a fictitious account, Dyson balls are most often depicted as Dyson shell with gravity difficulties and the techniques from above mentioned variants are ignored.
See also
References
External links
- Sphere Dyson FAQ
- Dyson sphere
- Toroidal Dyson collects simulations using Java applets
- FermiLab: the entire upper limit of the sky based on IRAS on Dyson balls, with a clear attachment of the Dyson scope engineering
- Dyson sphere in Memory Alpha (a Star Trek wiki)
- "Dyson sphere". TV Tropes. Ã,
Source of the article : Wikipedia
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