Matrioshka Brain

Quint Matrioshka
Image from Steve Bowers

Dyson-sized (or bigger) megastructure giving most efficient processing out-put for energy input; designed to maximize energy use and processing efficiency.

A Matrioshka brain consists of a series of energy collection units arranged in concentric shells or swarms, so that the waste radiation produced by the inner shell or swarm is utilized by the collectors of the next shell out.
The inner swarms receive a high energy flux, while the outer shells are cooler; each layer powers an appropriate recipe of computronium, tailor-made for that operating temperature. Processing elements near the stars could be nearly as hot as the star itself, while the outer layer of the swarm could be nearly as cool as interstellar space. The whole array comprises a highly efficient Dyson swarm with vast processing power.

If the outermost shell of a Matrioshka brain is very large (many astronomical units in radius), it may radiate at a similar temperature to the Cosmic Microwave Background and be effectively invisible at interstellar distances, except as an occulting object. However this requires a lot of material for the construction of the swarm; in some cases this material is obtained by starlifting. By extracting material from the star the rate of fusion can be controlled, allowing the construction of highly efficient hypernodes and micronodes.
The Silk God Diffusion Sphere
Image from Steve Bowers
This organically-grown Matrioshka Brain was created by the Silk God in the Red Star M'Pire
The computational elements of a typical Matrioshka brain are spread out over a very large volume, comparable in size to a planetary system. For this reason it would take a long time for information to pass from one side of a Matrioshka Brain to the other. This means that the computational speed of a Matrioshka Brain is limited by the speed of light.

To reduce this problem and increase the speed of processing in such an object, many Matrioshka Brains use wormholes to connect distant parts of its structure, so that information may pass more rapidly. Only very small Hayward-type wormholes can operate in the midst of a massive swarm of processing units, because of the fact that traversable wormholes require to be surrounded by asymptotically flat space-time. However Hayward wormholes require very large amounts of mass-energy to create.

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Development Notes
Text by Steve Bowers
Initially published on 02 September 2002.

Robert Bradbury's original paper on Matrioshka Brains can be found here
Planetary Disassembly - supplementary info (Robert Bradbury)
Additional Information
See Also Isaac Arthur's YouTube Channel
Matrioshka Brains