Matrioshka brain

A Matrioshka brain is a megastructure in space based on the Dyson sphere, of immense computational capacity. It ranges in size from an asteroid to an entire universe, where it can hold the energy of trillions of stars to drive insane computational power that can run simulations of an entire virtual universe.

It is an example of a Class B stellar engine, employing the entire energy output of a star to drive computer systems. The concept of a Matrioshka brain comes from the idea of using Dyson spheres to power an enormous, star-sized computer. The term originates from matryoshka dolls, which are wooden Russian nesting dolls. Matrioshka brains are composed of several Dyson spheres nested inside one another, the same way that matryoshka dolls are composed of multiple nested doll components. The innermost Dyson sphere of the Matrioshka brain would draw energy directly from the star it surrounds and give off large amounts of waste heat while computing at a high temperature. The next surrounding Dyson sphere would absorb this waste heat and use it for its computational purposes, all while giving off waste heat of its own. This heat would be absorbed by the next sphere, and so on, with each sphere giving off less heat than the one before it. For this reason, Matrioshka brains with more nested Dyson spheres would tend to be more efficient, as they would waste less heat energy. The inner shells could run at nearly the same temperature as the star itself, while the outer ones would be close to the temperature of interstellar space.

The engineering requirements and resources needed for this would be enormous. This could be used to simulate various cosmological structures:


A brain	Asteroid brain. Based upon a computational substrate comparable in mass and size to an asteroid. Smaller than a moon brain.
M brain	Moon brain. Based upon a computational substrate comparable in mass and size to a small moon or rocky core of a planet.
P brain	Planetary brain. Based upon a computational substrate comparable in mass and size to a rocky planet.
J brain	Jovian brain. Based upon a computational substrate comparable in mass and size to a gas giant planet. A Betelgeuse brain is a Jupiter brain so large that it has to be supported by its own radiation pressure to avoid collapsing.
N brain	Neutron brain. Based upon a computational substrate comparable in mass, size, and density to a neutron star.
S brain	Star brain or Godstar. Based upon a computational substrate comparable in mass and size to the most massive stars, at minimum 10 solar masses. Matrioshka Brains are typically deployed around stars and are therefore S-brains. Cluster brains consist of many Star brains and/or Matrioshka nodes linked together by wormholes. The creation of a cluster is done with grazers and large mass sources such as large stars, nebulae, and brown dwarf bodies.
W brain	Wormhole brain. Based upon a computational substrate consisting of large numbers of entangled wormholes.
B brain	Black hole brain. Based upon a computational substrate composed of the Cauchy horizon of a black hole.
G brain	Galaxy brain. A hypothetical entity able to draw upon the processing power of an entire galaxy's mass.
UV brain	Universe brain. A hypothetical entity capable of creating whole worlds. It's theorized that our universe is just the creation of a U brain. Laplace's demon cannot process an infinite amount of information. The limit on the computational power of the universe is based on the maximum entropy of the universe, the speed of light, and the minimum amount of time taken to move information across the Planck length, and the figure was shown to be about 10¹²⁰ bits. Accordingly, anything that requires more than this amount of data cannot be computed in the amount of time that has elapsed so far in the universe.
MV brain	Multiverse brain. A hypothetical entity capable of computing in across dimensions and the multiverse.

Matrioshka brains are way beyond yottascale computing:

1.12×10³⁶ FLOPS is its estimated computational power, assuming 1.87×10²⁶ Watt power (possibly solar) and 6 GFLOPS/Watt efficiency. This is for Type 1 prototypes.
A nanomechanical implementation of the computronium (which would allow us to push close to the Landauer limit of energy efficiency) could generate some 10⁴⁷ FLOPS. This is for Type 2.
Alternatively, 4×10⁴⁸ FLOPS is its estimated computational power where the power source is the Sun, with the ideal thermodynamic efficiency of a Carnot engine. This is for Type 2.
5×10⁵⁸ FLOPS is the estimated power of a galaxy used by Matrioshka brains. This is for Type 3.
A UV brain is capable of 10⁹⁰ operations per second.
If all matter in the universe was turned into a black hole it would have a lifetime of 2.8 × 10¹³⁹ seconds. During that lifetime such a B brain would perform 2.8 × 10²²⁹ operations.
If there are 10⁵⁰⁰ kinds of universes in a multiverse, then a quantum computronium MV brain could manage around 10⁶⁰⁰ operations per second.

Trivia[]

The Magratheans in the Hitchhiker's Guide constructed constructed a P brain, Earth, to determine the ultimate question of Life, the Universe, and Everything.