The Dyson Sphere, with no relation to the Dyson family of electronics, is a theoretical megastructure proposed by the legendary physicist Freeman J. Dyson in his 1960 article entitled “Search Artificial Stellar Sources of Infrared Radiation.”
Dyson pointed out that the exponential growth of an advanced extraterrestrial civilization’s energy demands could lead it to occupy “an artificial biosphere which completely surrounds its parent star.” The general premise behind such a structure is that if built encompassing a star (e.g., the Sun), it would be able to capture a large percentage of the star’s radiation energy (the Earth only intercepts a fraction of the Sun’s output), which is then converted and emitted as a lower frequency (functional) radiation (e.g., infrared). A habitable surface would also offer additional space for a continually expanding civilization.
Interestingly, however theoretical, the Dyson Sphere’s engineering shows no physical barrier to building large rigid structures in space. A type I (fragmented) Dyson Sphere can be built gradually with just the long-term deployment of more solar collectors and habitats. Planets can also (in principle) be deconstructed for their material in sufficient quantities to build a sphere of useful thickness.
It isn’t a matter of whether we can build a Dyson Sphere; we ought to be asking IF we should build a Dyson Sphere… at least for now. And here are five reasons why.
- Humanity has no need for this much energy until advancing into a Type II Civilization!
- The size of the proposed Dyson Sphere is simply too big…
- There is too much gravitational instability!
- There is too much mechanical instability!
- Can we really build a Dyson Sphere efficient enough to matter?
1. Humanity has no need for this much energy until advancing into a Type II Civilization!
According to the Kardashev Scale proposed by Nikolai Kardashev, civilizations can be classified into three types based on the development of their technology and increase in energy utilization.
*erg is a unit of power equal to 10-7 watt
| Civilization Type | Technology Level | Energy Consumption |
| Type I | A civilization capable of harnessing its home planet’s total energy and all the energy that reaches the planet from its star. Theoretically, humans could influence the weather, volcanoes, and maybe even earthquakes on Earth if we reached the Type I civilization status. | 4 · 1019 erg/s |
| Type II | A civilization capable of harnessing the total energy output of a star. This would theoretically make a civilization immune to extinction as it would obtain control of everything, including planets, asteroids, comets within the solar system. | 4 · 1033 erg/s |
| Type III | A civilization capable of harnessing the total energy of an entire galaxy. Civilizations of this type will be able to colonize the systems and harness and use the energy of all stars within the galaxy. | 4 · 1044 erg/s |
The purpose of a Dyson Sphere is to capture and generate enough usable energy from a star to support the growing needs of a civilization that has grown to require more energy than its planet can provide. As one would imagine, the successful construction of a Dyson Sphere would allow a civilization to reach the Type II status on the Kardashev Scale.
You might question why I say humanity has no use for this much energy. Isn’t more energy always better?
Well, hear me out.
In 1973, the astronomer Carl Sagan estimated humanity to represent a Type 0.7 Civilization, and more recent estimates put us at about 0.72. Our current state of technological development has enabled the production and use of nuclear energy, which has allowed for the creation of new industries, expansion of world markets and exploration into the realm of science fiction.
With all the benefits of nuclear energy, you can also use it to decimate countries and continents, and maybe even the entire planet in the process. As Futurism puts it, humans inherently fight to earn mating rights and protect hunting territories. In our society today, we constantly attempt to establish leadership through an economic-based dominance hierarchy.
Unless humanity can come together to prevent mass extinction or for the common cause of advancement, we might literally bomb ourselves back into the stone age.
Here comes the problem. Humans can’t share. The only way for humanity to advance beyond a Type 0 civilization is to learn to play nice with nuclear power. In reality, global warming itself is a manifestation of human greed and our inability to harness all the solar energy that reaches Earth as well as our planet’s total energy.
Do we need the total power output of the Sun right now? The answer is no. It might be another few thousand years before we would require that much energy. But a better question would be, even if we could harness the Sun’s power with a Dyson Sphere, whether it be right now or in a thousand years, is that really a good idea?
2. The size of the proposed Dyson Sphere is simply too big…
Many extensions of Dyson’s idea have been proposed over the years. However, not many focus on its structural feasibility, but rather how it can otherwise be utilized to serve its purpose for humanity. That is why, to date, only a precariously few studies have come to question one of the most fundamental aspects of the Dyson Sphere: Is it possible to build something this big?
When I say “encompassing a star,” what kind of a structure might come across your mind? Is the shape you’re thinking of something resembling a Ferrero Rocher, where the outer chocolate encompasses the inner core?
You’re right! That is exactly how the Dyson Sphere’s simplest and most popular form, a solid spherical shell, would be structured around the Sun. And its original design constitutes a sphere with a radius of 1AU (Astronomical Unit – the mean distance from the Earth to the Sun).
Now, if we really think about it, the Dyson Sphere would not simply encompass the Sun but also Mercury and Venus with a radius of 1AU. The amount of materials required to build such a structure quite literally does not exist on Earth as this sphere would also have to be of a useful thickness in the order of millimeters to meters. We would have to resort to asteroid mining or deconstructing other planet for their resources.
This is not to say we won’t have the technology to gather the required resources as humanity slowly progress towards a Type II civilization. But to satisfy the goal of the Dyson Sphere becoming habitable, the proposed radius for the sphere will simply not achieve the Earth-like gravity required for those ends.
Graphene has been proposed as a hypothetical material to build the Dyson sphere due to its ultimate tensile strength of 130 GPa for bulk graphite (multi-layer graphene), making it the strongest contemporary material. This is needed as the material must be sufficiently strong to survive a rotating sphere’s tensile stress.
Unfortunately, with a density of 2267 kg/m and a radius of one AU (1.496 · 1011 m), a Dyson Sphere constructed with graphite will have a resultant acceleration of 9.5 · 10-4 m/s2 (~0.01% of the gravity on Earth). This means that Earth-like gravity cannot be simulated on a Dyson Sphere with a radius of 1AU. The radius has to be 1/10,000 of 1AU (15,000 km).
This distance is so small (twice the Earth’s radius) that the resulting Dyson sphere built would literally reside in the solar interior rather than encompassing it. The logical choice would then be to place the structure in orbit around the sun rather than encapsulating it.
Unless we are able to find a way for humans to adapt to living in microgravity conditions, maybe we should leave the concept of such a large dyson sphere in the back burner for now.
3. There is too much gravitational instability!
The reasoning this article stands by is that the realistic construction of a Type II monolithic/rigid Dyson Sphere is entirely possible by our current technological standards. However, whether or not this structure will remain stable enough to enact its function is an entirely different story.
Before we begin, the concept of ‘monolithic’ and ‘rigid’ represents the indivisible and uniform nature of the type I Dyson Sphere, where the sphere is in itself one structure (solid shell). Compared to a fragmented type I sphere created by a loose collection of objects deployed around a star in a spherical shape.
The gravitational non-stability of the rigid Dyson Sphere can be derived from Gauss’s Law: the integral of the force across a closed surface is proportional to the amount of mass it’s made of. Accordingly, there would be no gravitational field inside the sphere as there is no force acting on its inner surface (the mass and gravity of the Sun are ignored as we are only interested in the gravity of the Dyson Sphere). Newton’s first law states: as the Dyson Sphere does not exert any force on particles inside itself, the particles inside the sphere will remain at rest.
But here comes the problem. Does having a non-existent gravitational field sound like a good thing? Not when there is a star inside you it’s not.
The perfectly spherical and rigid sphere will experience no net force from a star interior to it, which means the centers of mass of the sphere and the star are gravitationally uncoupled, so there is no reason for the sphere to stay centered on the star.
In its current state, the Dyson Sphere is said to be neutrally stable. This means it could easily become unstable as any external force (ex. impact of an asteroid) can cause the sphere to drift into the star. Simultaneously, the achieved neutral stability is only possible through the symmetry of a “perfect sphere,” and any deviation from this sphericity would also result in an unstable configuration.
In other words, we can go ahead and build the Dyson Sphere, but we would also need to figure out a way to keep it from drifting into the Sun.
4. There is too much mechanical instability!
The point above explored the instability of the Dyson Sphere as a result of its own gravity. However, we did not discuss the effect of the Star/Sun’s gravitational force, which might be so extreme it would completely crush a rigid Dyson Sphere supported by its own material strength.
This then poses difficulties from a mechanical perspective. A free-floating object around the star would not accelerate towards it under the force of gravity. One can simply invoke centrifugal force from an orbit. But this is not possible for a rigid sphere containing the star.
For a sphere containing the star, all of the area elements feel the same force, which causes the sphere to shrink and generate lateral and compressive forces between the elements. Due to the sphere’s curvature, there is a small outward component of the compressive force, increasing until the sphere shrinks enough for the compressive forces to achieve equilibrium. At this point, it is safe to say the rigid sphere finally appears to be mechanically stable.
Unfortunately, the circumstance explored above is purely hypothetical as real structures are not infinitely rigid and will deform if the external pressure and force exceed the material’s yield strength.
Calculations have yielded that it appears impossible for a Dyson Sphere of any size to support itself via elastic forces against gravity, even with the use of the strongest known material, carbyne. The elastic strength required exceeds even the carbon-carbon bond, which exists as the strongest (currently) in nature.
All the above problems are enlarged by the requirement for the sphere to be perfectly uniform and spherical. Any deviations from such sphericity will create additional differential forces, which might even cause a sphere built with a sufficiently strong material to collapse, as the sphere will no longer be able to achieve equilibrium during its compression.
Unfortunately, just like above, a type II Dyson Sphere can be built, but it might not last for as long as we think.
5. Can we really build a Dyson Sphere that’s efficient enough to matter?
After overcoming its instabilities, it is now time to consider the efficiency at which the Dyson Sphere can operate. Because, after all, that’s the job.
The maximum efficiency assumption is that all of the starlight is captured, and the Dyson Sphere must be long-lived. And due to the long-term nature of the work, the energy collected by the sphere will most likely be emissive or dissipative. The star’s energy cannot be very well stored on a cosmic time scale without heating up and literally unbinding the sphere. Only if the Dyson Sphere’s function is to deconstruct the star should we possibly find it doing lasting work.
But what if we need to store the energy? Are we just out of luck?
Not necessarily. The proposed solution for storing this energy in a manner that has significantly more capacity than heat or gravitational potential energy would be to store the energy as mass.
While converting starlight into protons would just be outright inefficient (we might as well be collecting energy from stellar winds at this point), the most plausible mechanism would be to convert starlight into antimatter.
At this point, we have two options. Either all the work by the Dyson Sphere goes into the creation of anti-matter or low-entropy radiation emission (which is what the Sun does regularly, just not as abundant or concentrated), or it’s emitted as waste heat through, for instance, completing computations (ex. heat released by our computers as we put it through our arduous everyday tasks).
It has been proven that for an infinitely large Dyson Sphere, it can, in principle, convert 99.9% of the energy in starlight into work. And in the case of low-entropy emissions, a Dyson Sphere with a radius of 1AU has a maximum efficiency of 97%. Computational-wise, the energy emitted as waste heat for a Dyson Sphere at a distance ‘R’ from the Sun would yield 1049 logical computations per second. This computational efficiency of 1% compared to the maximum possible rate will increase as the Dyson Sphere’s size infinitely increases.
As it seems, the bigger the Dyson Sphere, the more efficient it will be. But there is just a few problems.
With humanity’s current understanding of anti-matter, it will be quite a while before we can ever hope to begin its production. So, that’s out of the equation.
And unfortunately, like previously discussed, the amount of resources we would require to construct a Dyson Sphere of radius 1AU is already insurmountable. Not to say it cannot be done, but at our current state of civilizational advancement, is it really worth it to construct something of the Earth’s orbit size or even bigger to achieve a justifiable work efficiency?
It also seems we have not been able to find a solution to enable the habitable aspect of a Dyson Sphere with a radius of 1AU just yet. Which then comes down to a choice between work efficiency or habitability.
Dyson Sphere Theories You Might Find Interesting
1) Finding a Dyson Sphere over a White Dwarf.
The White Dwarf, as classified by the Hertzsprung-Russell (HR) diagram, represents the revolutionary stage of a low mass main-sequence star (like our Sun) which has exhausted all their possible fuel (hydrogen and higher elements) for fusion reactions, and are in the process of cooling by radiation. White dwarfs are formed after a red giant collapses inwards due to its own gravity and expels most of its outer material in the form of a planetary nebula.
Image by Richard Powell (Wikipedia)
It is reasonable to suggest that if interstellar travel is fundamentally problematic for a civilization, and its central star is no longer emitting enough radiation to sustain life, the logical next step would be to build a Dyson Sphere around the newly formed white dwarf to ensure enough energy is collected for the survival of the civilization, and possibly a new location for human habitation on the outside surface of the sphere.
This possibility was investigated by Semiz and Ogur, which showed that a smaller Dyson Sphere could be built around a typical white dwarf to simultaneously satisfy both the temperature and gravity requirements for human habitation. A Dyson Sphere at a smaller scale (but still able to provide 105 times the living area of a planet) would also require less building material than one constructed at an AU scale.
The Dyson Sphere’s proposed habitability depends on its temperature and gravitational field, which are both functions of its radius and the mass and luminosity of the white dwarf. By plotting the temperature-gravity and mass-radius relationship for all white dwarfs part of the HR diagram, Semiz and Ogur were able to determine that 55 of the 142 white dwarfs had conditions that’s within the region of constructing a habitable Dyson Sphere (Gravity: 6 m/s2 ≤ g ≤ 12 m/s2; Temperature: 260 K ≤ T ≤ 310 K).
The mass for constructing such a small-scale Dyson Sphere with Earth-like density (hypothetical), a radius of 3 · 106 km, and thickness of 1 meter was found to be 6 · 1023 kg, which is slightly less than the mass of the moon.
2) Harnessing the energy of a Supermassive Black Hole.
Here, we venture from the realm of science fiction into the realm of extreme science fiction.
A paper by Inoue and Yokoo published in the Journal of the British Interplanetary Society described a new energy system for “a society of highly advanced civilizations around a supermassive black hole (SMBH).” This system was named an advanced Type III “Dyson Sphere,” which can deliver energy from the SMBH to members of a galactic club formed by Type III civilizations, much like the energy control system similar to power grids in our present society.
Image by Robin Dienel/Carnegie Institution for Science
The premise behind such a theory is that “a society of highly advanced civilization is supposed to require a huge energy to operate their social system … the condition around an SMBH at the center of the galaxy would be more efficient both in extracting energy and exhausting the waste energy for advanced civilizations, than those of a Dyson Sphere.”
This Type III “Dyson Sphere” consists of power plants installed around the SMBH, where large amounts of radiation and potential energy of the accreting matter are released to form a hot and dense accretion disk. The SMBH would also be the final resting place for all waste materials for any civilization, while a sharp beam transmits the collected energy with coherent electromagnetic waves.
The proposed power plants’ structure essentially revolves around the central SMBH in Keplerian motion to form a partly covered “Dyson Shell,” as opposed to the fully covered Type II Dyson Sphere. These gaps are left in consideration for complex structures around the SMBH like relativistic jets, accretion disk and accreting matter, rapidly rotating stars, etc.
Although the exact transmission wavelength has not been proposed, three factors have been suggested to be taken into consideration:
- the spectral energy distribution of the radiation from the accretion disk
- energy conversion efficiency of the power plant for the transmission
- transmission efficiency through the interstellar medium
References
- The Kardashev Scale Type 0: Why Earth is a Level Zero Civilization. (2016, August 31). Futurism. https://futurism.com/civilization-type-0-living-in-a-subglobal-culture
- Shaw, E., Tudor, V., & Winkworth, D. (2012). A4_3 Habitable Dyson Sphere. University of Leicester. https://journals.le.ac.uk/ojs1/index.php/pst/article/view/2078
- Wright, J. T. (2006). Dyson Spheres. Serbian Astronomical Journal, 1–21. https://arxiv.org/pdf/2006.16734.pdf
- Darling, D. (n.d.). Dyson sphere. David Darling. Retrieved April 2, 2021, from https://www.daviddarling.info/encyclopedia/D/Dysonsp.html
- Semiz, I., & Ogur, S. (2015). Dyson Spheres around White Dwarfs. Bogazici University. https://arxiv.org/pdf/1503.04376.pdf
- Inoue, M., & Yokoo, H. (2011). Type III Dyson Sphere of Highly Advanced Civilisations Around A Super Massive Black Hole. Journal of the British Interplanetary Society, 64, 58–62. https://arxiv.org/pdf/1112.5519.pdf
