Scientists have long dreamed of an everyday “superconductor” that would carry electricity without the slightest loss. Besides saving billions in transmission cost, such a development could enable nuclear power plants to be located far from urban centers. Superconductors could make possible electric motors one-tenth normal size, high-speed trains levitated by magnets computer smaller and faster than today’s, and magnetic imaging machine inexpensive enough for everyday doctor’s office. Indeed, superconductors could transform technology on a scale unseen since the advent of the transistor