Kepler’s Conjecture: How a 400-Year-Old Puzzle Was Finally Solved Imagine stacking cannonballs in the tightest possible way. This simple, everyday problem turns out to be one of the most famous mathematical questions ever asked—and it took more than 400 years, plus modern computers, to finally settle it. This story is known as Kepler’s Conjecture, and it’s a remarkable journey from 17th-century intuition to 21st-century computer-verified proof. A Simple Question with Deep Consequences In 1611, t