Radioactive energy

Measured the heat emission of radium as it emitted radiation, discovering it released consistent energy over many centuries. This finding indicated a previously unknown energy source within the atom, leading to the concept of atomic energy.
 Pierre Curie France 1901 Radioactive energy

Measured the heat emission of radium as it emitted radiation, discovering it released consistent energy over many centuries. This finding indicated a previously unknown energy source within the atom, leading to the concept of atomic energy.