Perpetual nonsense

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.