This seemingly simple experiment had tremendous implications for the history of the human race. James Chadwick had discovered the third subatomic particle, the neutron, which had mass, but no charge.
If you recall, an alpha particle or a proton has a positive charge; therefore, when these particles are fired at an atom's nucleus, they will be repelled due to the nucleus and the incoming particles having the same charge.
However, if a neutron is shot toward a nucleus, it will not be deflected since the incoming neutron has no charge.
This simple difference allowed scientists to begin experiments in additional artificial transmutation reactions called fission reactions. Very large, unstable nuclei were bombarded with these neutral neutrons, causing the nuclei to split apart into two lighter elements and to release a tremendous amount of energy.
The nuclear era was born. A little over a decade later, the first fission bomb was dropped on Hiroshima, Japan, forever changing the landscape of international relations.
