Born on March 8, 1879, in Frankfurt am Main, Germany, Otto Hahn studied chemistry at the Universities of Marburg and Munich. Early in his career, he worked in radiochemistry, collaborating with leading scientists such as Ernest Rutherford and William Ramsay. Hahn’s initial contributions included the discovery of several radioactive isotopes, including radiothorium, mesothorium, and ionium, which laid the groundwork for future nuclear research.

In 1917, Hahn and Lise Meitner identified the element protactinium, further cementing his reputation in the field of nuclear chemistry. Their collaboration continued for decades, and although Hahn was cautious about making bold claims in physics, their joint work was instrumental in advancing the understanding of radioactive decay and nuclear reactions.

Hahn’s most significant achievement came in 1938 when, alongside Fritz Strassmann, he discovered the process of nuclear fission, where uranium atoms split into lighter elements, releasing vast amounts of energy. This discovery was later interpreted and named by Meitner and her nephew Otto Frisch, who explained the physics behind it. Hahn’s work directly influenced the development of nuclear energy and atomic weapons, though he personally opposed their use.