ALBERT EINSTEIN
In 1921, Albert Einstein won the Nobel prize for discovering the cause of photoelectric effect.
Atoms when bombarded with light emit electrons.
16 years earlier, Einstein defended that light divides into photons which he called "packets".
Albert Einstein went further to explain that when the packets in light strike atoms, the electrons in the atoms absorb the light and the electrons are excited.
Albert Einstein also came up with the theory of relativity, explaining the relationship between energy and mass which is summarized in his famous formula E=mc^2.
This formula was exploited in building of the atomic bomb, a great step in putting world war 2 to an end