One of the main quests of science throughout the ages has been to discover what matter is made of - and what holds it together. All matter is made out of many tiny particles called atoms. The study of how these atoms interact is called chemistry. Modern physics has discovered how atoms are made up of smaller particles and how these particles interact to build atoms into molecules and larger objects of matter.

The philosopher Democritus came very close to our modern understanding when he proposed that everything is made up of very small particles, which he called atoms, from the Greek atomus, for 'indivisible'.

In the 1600s, Sir Isaac Newton and other scientists experimented with materials, light, and heat, and developed many basic laws of physics. By the early 1800s, the theory of the atom became popular. By the 1900s, scientists had discovered that atoms are themselves made of even smaller particles. This century research in particle physics has taken us deep into the heart of the atom, far beyond the limits of the most powerful conventional microscopes.