The discovery of radioactivity has been called the most dramatic scientific breakthrough of our time. From the initial experiments came an understanding of the inner workings of the atom and the establishment of a new science, nuclear physics. Though many were to follow him, Henri Becquerel was the first to experiment with radioactivity. Quite by accident, he observed the mysterious energy emitted by uranium, and his research sparked a new wave of scientific theory.

That Becquerel became a scientist was of no surprise to his family--both his father and grandfather before him had been physicists. Becquerel's father had specialized in the study of fluorescence, and Henri began his own research in this field while attending college. He received his engineering degree in 1877 from the École des Ponts et Chaussees, after which he entered the Administration of Bridges and Highways. During this time, his wife of four years...