Dyson Sphere



""Imagine the energy crisis of a really advanced planetary civilization. They've used up all their fuels, they depend on solar power. An enormous amount of energy is generated by the local star, but most of the star's light doesn't fall on their planet. So perhaps, they would build a shell, to surround their star, and harvest every photon of sunlight. Such beings, such civilizations, would bear little resemblance to anything we know."

- The Dyson Sphere, in a nutshell, as described by Carl Sagan.

Big Dumb Object or That's No Moon not big enough for you? Look no further. Sci Fi authors have made solar-system-sized artifacts into a trope of their own. The Trope Namer is physicist and mathematician Freeman Dyson, who theorized in a 1959 scientific paper that, given the ever-increasing demand for energy typical of industrial civilization, Sufficiently Advanced Aliens might need to capture all the energy radiating from a star.

While Dyson himself originally saw his concept as a cloud of many separate orbiting habitats and power-stations, most media depictions show a single continuous solid shell completely enclosing its star. This is an acute case of Sci-Fi Writers Have No Sense of Scale. Constructing such an artifact would probably put a civilization at least 2.0 on the Kardashev scale.

The technologies and resources needed to do it raise the question of whether a race that could build one would still need it. It has been estimated that constructing the sphere would require the energy equivalent of the lifetimes of several stars AND the raw materials of more than the entire solar system, which rather defeats the purpose of the initial construction.

For a real-life example: there is absolutely nothing stopping the human race from building a bridge across the Pacific Ocean. Humanity has all the engineering know-how and resources needed. So why haven't we? Well, we already have ships and airplanes, not to mention things like videoconferencing -- these are all already-existing ways to bridge the Pacific using the very same know-how and technology which would let us build that hypothetical bridge in the first place.

The Ring World concept was created by science fiction author Larry Niven as a mid-point between this and a true planet because, as Niven put it in his essay Bigger Than Worlds (a discussion of Ring World Planets, Dyson Spheres, and other possible macrostructures), "I like being able to see the stars at night". Something that a Dyson Sphere prevents.

This trope doesn't require an object to block all light from the star, but it does require construction on that scale. To be a Dyson Sphere, the artifact must:


 * 1) be an artificial structure. Naturally-occuring structures don't count, though a nest built by a Space Whale would.
 * 2) contain a star inside it (that is, a giant ball of gas lit by stable nuclear fusion initiated by the pressure on its core due to its own gravity, not some little glowing speck or a mythological god with a lantern, OK?)
 * 3) contain an inside surface where people can survive (possibly with space suits) without being burnt to a crisp by the star.
 * 4) be at least the size of a small solar system. Typically we're talking 100 million kilometers or more.

In fiction, Dyson Spheres tend to be abandoned and uninhabited. If they are inhabited, the residents are usually not at a tech level capable of building the sphere. This is because, if your protagonists run into a sphere whose residents are in the full flower of their technological might, they and their problems promptly get overwhelmed.

Subtrope of Hollow World. Compare Big Dumb Object and That's No Moon. Not to be confused with the Dyson Ball, which is part of a vacuum cleaner.

Some useful notes on the Real Life physics of objects this size:

 * In response to letters prompted by his original paper, Freeman Dyson replied: "A solid shell or ring surrounding a star is mechanically impossible. The form of 'biosphere' which I envisaged consists of a loose collection or swarm of objects travelling on independent orbits around the star." The evolution of the term "Dyson Sphere" is an example of Memetic Mutation. Dyson himself referred to his idea as a "shell" or "swarm", and his use of "biosphere" was in the ecological, rather than any geometric sense. But then Rule of Cool caught up with him.
 * The surface gravity of the outside of a stereotypical 1-AU solid shell is likely to be negligible. Gravitational acceleration due to the Sun out there is less than 1/1000 g. Calculus and physics (the Shell Theorem) tell us that the gravitational effect of any spherical shell we're outside of is equivalent to that of the same mass as a point source at the shell's center; we can assume that the sphere doesn't have mass orders of magnitude more than the Sun, considering that it has to be made of locally available materials and the Sun weighs much more than everything else nearby combined, so don't expect much.
 * Also, increasing the mass of the star increases its brightness, so the sphere would be larger as well.
 * It might be possible that a Sufficiently Advanced Alien has a reason to build a Dyson Sphere around a white dwarf, neutron star, or black hole, or has to build a smaller, 'hot' Sphere. In that case the gravity might be higher.
 * The surface gravity on the inside of a 1-AU solid shell is also negligible. Newton's shell theorem predicts that the gravity anywhere inside a hollow sphere would actually be zero, so that the main gravitational force acting on a body at the inside surface would be the star at the center, which as stated above is not large.
 * Spinning such an object would allow for near-normal gravity at the surface, but as was discovered by Larry Niven, the strength-to-weight ratio of the material required to withstand 1g of centrifugal force across this scale would be something around 1000 times that of steel.
 * Of course, Speculative Fiction writers are allowed to Hand Wave it as 'a network of gravity generators', Functional Magic, etc.
 * A Klemperer Rosette is a group of objects set to orbit together in a rotating pattern. Technically this may count if it's big enough to be considered a small solar system, and the objects were placed there artificially.
 * A solid Dyson Sphere would not be stable around its star without some form of correctional thruster system or Applied Phlebotinum to keep everything bolted in place.
 * Harder settings may couple the star to the mass streams of active supports holding up the sphere.
 * A point which is often ignored is that a solid shell will not only have eternal day, but also, instead of reflecting sunlight into space, will reflect it upon the sphere itself. This means that a shell around a Sun sized star will have to be not 300 million km across, but more likely about twice as much in order to maintain reasonable temperatures or using materials either with high efficiency in the production of energy (if the interior wall is dedicated exclusively to energy production) or with a high thermal conductivity coupled with an interior wall with high absorption of radiation.
 * A reasonable partial solution to this is for a star-faring society (and any society able to build a Dyson Shell is likely to be star-faring at least potentially) to select a smaller, cooler star (say a class M) and build their Shell around it, letting it heat up to hotter intensities due to reflection.
 * A Dyson sphere could be used as a computational node for a single massively powerful supercomputer, presumably either a segment of, or the entire physical being of, some kind of massively advanced Artificial Intelligence entity, presumably of the post-Singularity kind. Such an entity would be called a "Matrioshka brain" named after Russian Matrioshka dolls, because it may consist of layers of Dyson shells within each other, the inner layer being devoted to energy harvesting while the outer structures are devoted to computation.

Anime & Manga

 * Blame takes place inside of one. This is hinted at throughout the story, but the biggest piece of evidence comes later on when the protagonist finds a chamber that is absolutely massive. Its measured diameter is the same as that of the planet Jupiter.
 * This theory is given more creedence in the prequel NOiSE, where a self-replicating superstructure begins construction, enveloping  by the end of that series. It can be inferred that the massive room in BLAME! is.
 * The ending of Futaba Kun Change reveals the . It Makes Just as Much Sense in Context
 * While not spanning the entire Solar System, in Sol Bianca is like this. Interestingly, the government tries to hide the fact that the plant is already dead and thus the people live ON the sphere, not shielded by it on the planet.

Comic Books

 * New Mutants, an X-Men spin-off from Marvel Comics, featured a Dyson Sphere belonging to Cannonball's then-girlfriend, Lila Cheney.

Literature

 * In Alastair Reynolds's House of Suns, Dyson Spheres made out of perfectly reflective Ring World Planets are used to encapsulate stars that are about to go supernova.
 * Orbitsville and Orbitsville Departure by Bob Shaw featured a solid Dyson Sphere. (But in this troper's opinion totally wasted the concept on soap-opera plots.)
 * Larry Niven's Ring World: the Puppeteers' Fleet of Worlds is a Kemplerer [sic] Rosette.
 * The Ring World itself is a "flattened" Dyson Sphere - it is described as being like a ribbon encircling its sun, nearly a million miles wide and 300 million miles in diameter.
 * A Dyson Sphere made of a forcefield holds the Sealed Evil in a Can in Peter F. Hamilton's Commonwealth Saga.
 * The humorously tiled The Millennial Project: Colonizing the Galaxy in Eight Easy Steps features a more realistic version of a Dyson Sphere called a Dyson cloud. See here for more details.
 * It also proposed a solar-cell sphere around the orbit of Mercury, held up by the solar-sail effect and leaving a gap around the ecliptic for the planets and the aforementioned cloud.
 * Illegal Aliens. The inside of the shell was covered in solar collectors, and the people lived inside the shell, as basically it was a big spherical shaped space station.
 * Neal Asher's novel Polity Agent features the Cassius Project, humanity's first attempt to construct a Dyson Sphere. One of the subplots kicks off when an antagonist tries to sabotage its construction.
 * Iain M Banks's Culture novels have Orbitals, which seem suspiciously similar to Ringworlds.
 * Orbitals are actually a lot smaller that Ringworlds - think Halo (it's where Bungie got the idea in the first place). The Culture does have Ringworlds (they lost three in the war with the Idirans) but they're rare and regarded as somewhat wasteful since you could build thousands of orbitals with the same material.
 * Dyson Spheres are referenced in the casualty list of the Culture/Idiran War at the end of Consider Phlebas.
 * The Doctor Who New Adventures novel The Also People is set in a Dyson Sphere inhabited by a society which seems suspiciously similar to Iain M. Banks's Culture.
 * Part of The Time Ships by Stephen Baxter is set in a Dyson Sphere.
 * In the final Hyperion book, The Rise of Endymion, the Ousters are growing an organic Dyson Sphere around a star. It does not have gravity. While
 * The title object in Wall Around a Star.
 * Second Genesis by Donald Moffitt is mostly set on a Dyson Sphere composed of planet-orbit sized disks, used to power a massive interstellar transmitter (The rest of the story is set on another of Dyson's conceptual objects, a Dyson Tree that has been converted into a Living Ship).
 * William Forstchen's Gamester Wars universe has a Dyson Sphere setting that's still being built-- the Precursors' ancient robots have been at it for millions of years and it's still only half-complete, because it's big. There's also a Ringworld Planet and other stellar-scale objects in the same universe.
 * Half of Century Rain is set in one of these, but it wasn't built for the normal reasons. The inside of the sphere is patterned with stars that match the stars in our own solar system, and by some pseudo-scientific method they shift as our own stars would, so that those inside the sphere don't know that they're not really on Earth.
 * In Robert Silverberg's Across a Billion Years, some archaeologists discover an artifact left behind by a billion-year-old vanished civilization that leads them to the Dyson Sphere that the civilization disappeared into.
 * Xenology lists several projects beyond even the scale of a normal Dyson Sphere.
 * George Zebrowski's Macrolife mentions an alien solar system that consists of Worldships orbiting a black hole in a Dyson cloud.
 * Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization discusses several types of Dyson Sphere-scale projects and construction materials, as well as "Galactic Megastructures" which are even larger.
 * The jungle world of Pryan (World of Fire) in the Death Gate Cycle is eventually revealed to be a Dyson's Sphere. Not much is done with this concept, apart from the facts that there is no night on the planet except in areas where night cycles are created by artificial means, and its nature makes navigating the planet when one was expecting a more normally arranged world rather difficult.
 * In Housuke Nojiri's Usurper of the Sun, the Sufficiently Advanced Aliens start building one around ours.

Live Action TV

 * Star Trek had multiple instances:
 * In a Star Trek the Next Generation episode, the Enterprise encounters such a sphere that was left abandoned for some reason, where an engineer had crashed his shuttle. The characters themselves, even with all their advanced technology and having encountered far more advanced aliens, are astonished that anybody would be capable of building such a thing.
 * There's also one in Star Trek: New Frontier, but called a Thul Sphere after the financier. Needless to say, it gets blown up.
 * In the non-canon novel series Star Trek: Titan, the crew of the U.S.S. Titan uncover evidence of the existance of what may be the largest lifeform in the galaxy, a living Dyson Sphere distantly related to an alien lifeform the Enterprise encountered in The Next Generation pilot, "Encounter at Farpoint".
 * In one of the other non-canonical novels, part of the Star Trek: Millennium trilogy, O'Brien is trapped in one of these for what seems like years as the Fate Worse Than Death meted to him by the Pah-Wraiths.
 * In Gene Roddenbery's Andromeda the Magog Worldship is somewhat closer to the original concept of a Dyson Sphere but even more fantastic in some ways. It consists of twenty inter-connected planets surrounding an artificial sun. If the stresses involved in connecting twenty planet-sized bodies in stable orbits around a sun isn't enough, the entire thing could move.

Tabletop Games

 * One of the C'tan stargods in Warhammer 40000 is sealed inside a Dyson Sphere. Whether it was imprisoned or sealed itself there is not quite clear (although the background seems to suggest the latter).
 * Traveller. A Klemperer Rosette created by the Ancients exists in the Tireen system in the Vargr Extents.
 * Spelljammer... First, Crystal Spheres as such (e.g. Realmspace has pseudo-stars, walking cursed people and big magical scroll-like writings on its inner surface). Also, while Penumbra's Stellar Well isn't a Dyson Sphere, it's a large enough part of it, and the disk behind it is of Dyson Sphere scale.
 * Mage: The Ascension has a Dyson Sphere that belongs to the Void Engineers; the Copernicus Research Center functions as an Earth-away-from-Earth for a large number of Engineers, researchers, and their families. This actually puts the Void Engineers under suspicion: People started thinking that it'd be unlikely they managed to build 'The Cop' on their own, and some wonder if they got it from some... "friends"... they met beyond the stars. In one outcome of The End of the World as We Know It, the Void Engineers retreat to the Sphere en masse and leave the Universe in their own portable biosphere.
 * AT-43's Therians freaking love Dyson Sphere, so much in fact they plan on making the whole universe into them.
 * Magic: The Gathering has a plane called Pyrulea, which is a Dyson Forest.

Video Games

 * Prey takes place, for the most part, in an organic/cybernetic living Dyson spaceship, the "Sphere". It's essentially a smaller version of this trope, with a small dwarf star at its core.
 * Shows up in the final level of Freelancer.
 * Strangely, the world of Atreia in the MMORPG Aion was one. Then it broke.
 * Halo Wars has a micro Dyson Sphere in the finale. The Expanded Universe has one the size of a solar system; time passes much slower inside the sphere than it does outside.
 * Here an actual reason for why an advanced civilization would build one is given. The Shield Worlds were bunkers where the Forerunners would take shelter when the Halo Array was triggered; considering they were trying to shelter the entire population of an interstellar empire and possibly less-advanced sentient species, it is understandable they would need a lot of room.
 * Halo 4 will take place largely from within a Dyson Sphere called Requiem. It is similar to the Halo Wars example, but instead of an "inside-out" planet, this sphere is a shell which contains another planet inside. The shell does appear to have a geology of its own, though.
 * In Infinite Space, ..
 * In Mass Effect 2, Legion states that the end desire of the mainstream geth is
 * You can actually build one, as of Space Empires IV... or you could build a massive war fleet for one-tenth the cost.
 * One alien race in Fargate has one of these as their home system. As these aliens possess no apparent mechanical technology but are the masters of biological manipulation, the entire double-layered Dyson Sphere is grown organically. It looks very fleshy.
 * In X3 Terran Conflict,
 * The Ascent to Transcendence ending of Sid Meier's Alpha Centauri suggests a variant: "stellar encapsulation," effectively bottling the star without dismantling the planets of the system or otherwise affecting their biospheres.

Webcomics

 * The F'sherl-Ganni of Schlock Mercenary have built several of these. They call them "buuthandi", a shortened version of a F'sherl-Ganni phrase that roughly translates to "This was [expletive] expensive to build" (fully transliterated as "expensive and expensive-expensive [expletive] we built."). At one point, the characters gather a fleet to assault one.
 * The author tried to depict them more realistically then a solid shell build around a star. In this setting Dyson Spheres (there are 5, well 4 now after one was destroyed) are constructed from a flexible material. They are practically bubbles around a star kept inflated by the solar wind. Habitats are anchored to the interior of the sphere. Setting also has widespread gravity generators, so that's not a problem either.
 * The Sluggy Freelance Punyverse is revealed to be contained in one.
 * In Dreamwalk Journal the world of Cyeatea, with its immense jungle housing a peaceful culture of sexually-insatiable anthropoid insects and spiders, is apparently a habitat within a Dyson Sphere called Velveteen. However, there is only one reference to this in a related text piece.

Web Original

 * Many types appear in Orion's Arm. Most impressive is probably the suprastellar shell, a solid Dyson Sphere (actively supported) that people live on the outside of.

Western Animation

 * Umbra, the Big Bad in the 1984 animated series Mighty Orbots WAS a Dyson Sphere. He was the core of the Shadow Star, a world so large it contained its own internal sun.

Real Life

 * There are quite a few stories of small children getting the misconception Earth is like this.
 * And of some grown-ups mimicking this, completely disregarding the fact that Earth would be a Dyson Sphere if the Hollow Earth theory was proved true. To summarize: Earth is hollow and there is a tiny star inside, providing enough heat and light to sustain life. It Gets Worse when you ask them who is inside.
 * Some folks at SETI want to use some recently installed IR telescopes for searching after Dyson Spheres. While some feel it would be a waste of the usage time of a scientific instrument, others say that these spheres should stick out like sore thumbs and therefore it would be silly at least not to check.
 * This has been done, as part of the WISE spacecraft's all-sky infrared survey. Among other things, WISE was designed to discover brown dwarf stars with surface temperatures similar to Earth's within ~30 lightyears of the Sun. It would also have found 1-AU-radius Dyson Swarms around Sun-like stars out to >3000 lightyears. It didn't find any.