2. Atoms

Abstract

‘Atoms’ describes how humans discovered that the world is composed of atoms, even though they are invisible to the unaided eye. Starting with the prescient ideas of the Ancient Greeks 2,500 years ago there were, by the time of the Enlightenment, three ideas for a definition of matter: all matter is made of atoms, atoms take up space, and atoms have mass. The concept of atoms became more firmly rooted with the chemical experiments of the 19th century, but it was not until Albert Einstein’s interpretation of Brownian motion (the random jiggling of tiny dust particles) in 1905, that any last objections to the atomic hypothesis were finally quashed.