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Revision as of 00:11, 7 May 2006 by 24.166.6.153 (talk) (→Planetary scale)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)In science fiction and speculative (or exploratory) engineering, a megastructure is an enormous self-supporting artificial construct. The definition is often informal and varies from source to source, but generally requires at least one dimension to be in the hundreds of kilometers. Other criteria such as rigidity or contiguousness are sometimes also applied, so large clusters of associated smaller structures may or may not qualify. The products of megascale engineering or astroengineering are megastructures.
Megastructures are also an architectural concept popularized in the 1960's where a city could be encased in a single building, or a relatively small number of buildings interconnected together.
Megastructures often play a part in the plot or setting of science fiction movies and books.
Existing megastructures
There are structures on Earth that may be considered megastructures, such as
- The Great Barrier Reef, at 2,000 km in length
- The Great Wall of China is a human-built megastructure, 6,700 km in length.
Networks of roads or railways, and collections of buildings (cities and associated suburbs), are usually not considered megastructures, despite frequently qualifying based on size. However, an Ecumenopolis might qualify.
Theoretical megastructures
Stellar scale
- Alderson disk
- Dyson sphere (also known as a Dyson Shell)
- Matrioshka brain
- Shkadov thruster
- Stellar engine
Planetary scale
Orbital structures
- Bernal sphere (with a maximum diameter of 16 kilometers)
- Stanford torus (diameter just under 1.7 kilometers)
- O'Neill cylinder
Trans-orbital structures
Fictional megastructures
Stellar scale
- Larry Niven's series of novels about his Ringworld originated the concept.
- The Dyson shell has appeared in many works of fiction, including the Star Trek universe.
- In the manga Blame! the Megastructure is a vast and chaotic complex of metal, concrete, stone, etc, that covers the whole Earth and assimilates even the Moon. There is even a clue by the end of this manga that suggests the assimilation of Jupiter. The Megastructure continues to expand by itself, being built by robots called builders. The whole history of the manga takes place deep inside of the structure, where there is no sea or sky, and the characters find themselves climbing up thousand of kilometers of labyrinths searching for Net Terminal Genes. It has been suggested by Tsutomu Nihei himself that the Megastructure is actually a growing dyson sphere of gargantuian proportians.(Speculated to be roughly the size of Jupiters planetary orbit.)
Planetary scale
- Death Star
- Buster Machine III from Gunbuster.
- Culture Orbital
- In The Hitchhiker's Guide to the Galaxy series, Earth, as well as other planets, were artificial megastructures. Earth was intended to function as a gigantic computer, and was built by a race of beings who made their living by manufacturing other planets.
- In the Transformers universe, Unicron is a recurring megastructure that resembles a giant planet with large mandibles that can transform into a gigantic humanoid robot.
- The Star Forge from Knights of the Old Republic
- The seven Halos from the Halo: Combat Evolved universe are 10,000 km wide rings designed to wipe out all sentient life in the Milky Way galaxy.
- In the Robotech Sentinels novels, Haydon IV is an artificially constructed cyber-planet with android citizens.
Megascale structures
Structures that might not be classified as "Megastructures" because they do not meet the requirements, but are indeed "Mega" sized structures/constructions.
Stellar scale
- Dyson Bubble - Collection of separate constructions.
- Dyson Swarm - Collection of separate constructions.