The Discovery of the Atom's Hidden Structure

In 1897, at the Cavendish Laboratory in Cambridge, J. J. Thomson studied the mysterious rays produced inside cathode-ray tubes and showed they consisted of particles far lighter than any known atom and carrying negative charge. This was the discovery of the electron, the first known subatomic particle, and it shattered the ancient assumption that atoms were indivisible. Thomson went on to propose the "plum pudding" model, picturing electrons embedded in a diffuse cloud of positive charge, and received the 1906 Nobel Prize in Physics for the discovery.