The Ultimate Question

The Answer to the Ultimate Question of Life, the Universe, and Everything

In The Hitchhiker's Guide to the Galaxy novel, a group of hyper-intelligent pan-dimensional beings demand to learn the Answer to the Ultimate Question of Life, The Universe, and Everything from the supercomputer, Deep Thought, specially built for this purpose. It takes Deep Thought 7½ million years to compute and check the answer, which turns out to be 42. Deep Thought points out that the answer seems meaningless because the beings who instructed it never actually knew what the Question was.

When asked to produce The Ultimate Question, Deep Thought says that it cannot; however, it can help to design an even more powerful computer that can. This new computer will incorporate living beings into the "computational matrix" and will run for ten million years. It is revealed as being the planet Earth, with its pan-dimensional creators assuming the form of white lab mice to observe its running. The process is hindered after eight million years by the unexpected arrival on Earth of the Golgafrinchans and then is ruined completely, five minutes before completion, when the Earth is destroyed by the Vogons to make way for a new Hyperspace Bypass.

In The Restaurant at the End of the Universe, this is revealed to have been a ruse: the Vogons had been hired to destroy the Earth by a consortium of psychiatrists, led by Gag Halfrunt, who feared for the loss of their careers when the ultimate question became known.

Lacking a real question, the mice decide not to go through the whole thing again and settle for the out-of-thin-air suggestion "How many roads must a man walk down?" from Bob Dylan's song "Blowin' in the Wind".