/van'*-var/ A bogus technological prediction or a foredoomed engineering concept, especially one that fails by implicitly assuming that technologies develop linearly, incrementally, and in isolation from one another when in fact the learning curve tends to be highly nonlinear, revolutions are common, and competition is the rule. The prototype was Vannevar Bush's prediction of "electronic brains" the size of the Empire State Building with a Niagara-Falls-equivalent cooling system for their tubes and relays, a prediction made at a time when the semiconductor effect had already been demonstrated. Other famous vannevars have included magnetic-bubble memory, lisp machines, videotex, and a paper from the late 1970s that computed a purported ultimate limit on areal density for integrated circuits that was in fact less than the routine densities of 5 years later.

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