As with any historical story, there has to be a beginning. But of course one story is just a part of a larger history, and what comes before explains what happens as a result. In telling the story of Canada's most ambitious and productive science facility, there is much that happened before its story begins.
The great scientific progress of the previous century seemed to be ever accelerating as the 20th century dawned. Knowledge in physics and chemistry was building a great rate. All but five of the eighty two stable elements in the periodic table had been identified. Atoms were known to contain positively charged protons and negatively charged electrons. Rutherford, Curie and others were examining unstable elements, those that had a tendency to emit energy and decay into a stable state.
Early in the 20th century Rutherford demonstrated that an atom had a small dense nucleus surrounded by electrons at some distance. He also proposed the existence of a neutral particle within the atom, but it was not until 1932 that Chadwick discovered the neutron. It's lack of electrical charge made it difficult to detect.
So in the mid 1930s as world moved toward the second great conflict of the century, the basic knowledge was in place for further exploration of the atom. In 1939, in an experiment designed to disprove earlier work by Joliot-Curie, Otto Hahn bombarded uranium with neutrons and found barium in his experimental results. This was a startling event, barium is a much smaller atom than uranium and could not be produced by any known chemical process. Hahn had in fact split a uranium atom into two pieces: nuclear fission.
It was soon recognized by scientists across the world that uranium possessed important properties. If a uranium atom gained a neutron it split apart, releasing energy and also producing two or three more neutrons. If those neutrons could be used to split further uranium atoms, a continuous process could be imagined that would generate energy from within atoms themselves.