Matrioshka brain

Dithered illustration of Matrioshka brain

A Matrioshka brain is a star wrapped in nested shells of computers, each running on the heat the shell inside throws away. The physics says the extra shells barely help.

In 1997 Robert J. Bradbury asked how much computing a whole star could power. His answer was Dyson spheres nested like Russian dolls: the innermost shell computes hot on starlight, and each shell outside it runs on the waste heat of the one within. The prize is vast: the Sun emits more than 100 trillion times the electricity humanity produces. Yet an analysis of the thermodynamics found the extra shells add little or nothing. The material generally does more as small, hot spheres.

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