It can look almost too easy: athletes gliding along on a bike, runners shuffling at a pace slower than most people's warm-up, or someone strolling so gently it barely seems like exercise at all. Yet ...

It can look almost too easy: athletes gliding along on a bike, runners shuffling at a pace slower than most people’s warm-up, or someone strolling so gently it barely seems like exercise at all. Yet ...

Zero-point energy sits at a strange crossroads between hard physics and science fiction, promising limitless power from the fabric of space itself. If it could be tapped in any practical way, it would ...