BEYOND the suburbs of science dwell all manner of amateur inventors, would-be Einsteins, saviours of the planet and other well-meaning crackpots. The one thing they invariably share is a fascination with science and a less than rigorous grounding in its fundamentals. A good number seem bent on bequeathing some marvel of engineering that can generate an endless supply of free energy—in short, a perpetual-motion machine.

Nowadays the United States Patent and Trademark Office (USPTO) refuses to review a perpetual-motion machine unless it is accompanied by a working prototype. In the past too many inventors had used patents to convince gullible investors that their machines had been “officially approved” by no less an authority than the USPTO. Other such tinkerers are sincere and often genuinely puzzled by the way their devices appear to work. As a rule, however, there’s a belief that, somehow, the laws of physics do not apply to their particular contraption.