Mostly Empty

Ernest Rutherford was born on August 30, 1871, in Brightwater, New Zealand. He would discover the structure of the atom and reveal that matter is mostly empty space. Before Rutherford, the atom was imagined as solid, or perhaps a "plum pudding" of positive charge with electrons scattered through it. He proved it was something far stranger.

In 1909, at Manchester, he directed Geiger and Marsden to fire alpha particles at thin gold foil. Most passed straight through. Some deflected at large angles. A few bounced back. Rutherford said it was as if you fired a cannonball at tissue paper and it came back. Something small and dense inside the atom was responsible.

He concluded the atom had a tiny, dense nucleus containing most of its mass, surrounded by electrons at enormous relative distances. The atom was almost entirely empty space. If the nucleus were a marble, the nearest electron would be a football field away.

This nuclear model, published in 1911, replaced the plum pudding model and became the foundation for modern physics. Bohr refined it. Quantum mechanics complicated it. But Rutherford's basic insight remains correct.

ernest rutherford, the new zealand physicist born august 30, 1871, who discovered the nucleus of the atom and established the basic architecture of matter. source: wikimedia commons

In 1917, he achieved the first artificial nuclear reaction, transmuting nitrogen into oxygen. The ancient dream of alchemy, achieved through physics. He won the Nobel Prize in Chemistry in 1908 -- before his most famous discoveries. He reportedly joked the fastest transformation he'd seen was his own, from physicist to chemist. The man who found empty space inside everything left no empty space in physics.