Deep Thought was a supernatural-computer programmed to calculate the answer to the Ultimate Question of Life, the Universe, and Everything. It designed the other supercomputer Earth, which was built by the Magratheans.
Two programmers named Lunkwill and Fook were chosen to propose the Ultimate Question to Deep Thought on the day of the Great On-Turning. Before accepting its assignment, Deep Thought advised the programmers that there it would be surpassed in the future by another computer. As to answering the Magratheans' question, Deep Thought decided that it would "have to think about it", telling the programmers that it would take the computer 7.5 million years to calculate the answer to their Ultimate Question.
Seven and a half million years later, the descendants of Lunkwill and Fook - Loonquawl and Phouchg - presided over the Day of the Answer, and were chosen to receive the answer to the Ultimate Question. Deep Thought revealed that the Ultimate Answer was 42. When the Magratheans evinced their dismay that 42 was the answer that they had waited millions of years for, Deep Thought chided them for not understanding what the question was. The hapless programmers were further dismayed to hear that the computer itself was incapable of determining what the question was. Instead, the computer designed its successor, the superior computer it had hinted at millions of years earlier. Deep Thought announced that the new machine would be so large, it would resemble a planet, and be of such complexity that organic life itself would become part of its operating matrix. The Magratheans themselves would evolve into the mice, and descend to the planet to operate its 10 million year long program, and that new machine would be known as the Earth.
Nearly 10 million years later, just five minutes before it could reach The Question, a Vogon Construction Fleet destroyed Earth to make way for a hyperspace by-pass.
Deep Thought appeared or was mentioned in:
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