Planetary Computation Unit

Bratton's yardstick for planetary computation taken as a whole: one PCU is the aggregate artificial computing capacity on Earth at a given moment, roughly one zettaFLOPS (ten to the twenty-first operations per second) in 2025. Introduced in entry 9 of Accept All Cookies, restated in The Noocene as a "Planetary Computing Unit", and used in the Diffusion announcement to set a design horizon: with capacity doubling about every thirty months, 10 PCU arrives within a decade and 100 PCU within two, a world Bratton says will be as unfamiliar as today is to our grandparents. The unit turns Planetary Computation from a description into a quantity. A pointed precedent is The Stack, where a zettaflop climate simulator was a hypothetical the size of Paris whose energy use would be the largest climatic event it modelled; a decade later that figure is the baseline. No text shows how it was estimated.