Accidental Genius

"In 1044, a Chinese manual on producing gunpowder-based weapons included cannons, bombs for lobbing at invaders, two-stage rockets, and land mines." Chinese researchers stumbled across the formula for gunpowder while researching what they called the "immortality pill".  What forces control the way inventions end up being used? Mark RobinsonAccidental Geniusb> (Wired)