The discovery of radioactivity in 1896 represents a major step in the history of the physical sciences. This scientific revolution not only transformed our understanding of matter, but also paved the way for crucial advances in medicine, nuclear physics, and chemistry. A review of a key moment that upset the scientific certaintys of the late 19th century.

Historical context of the discovery of radioactivity

At the end of the 19th century, physics progressed considerably, notably with the study of X-rays discovered by Wilhelm Röntgen in 1895. The atom, previously considered the smallest indivisible unit of matter, was the subject of intense debate as to its structure and stability. On the other hand, the properties of the chemical elements were known, but their deepest behaviors remained mysterious. In this context of scientific exploration, the phenomenon of radioactivity would emerge as a natural phenomenon previously unknown, capable of questioning the very foundations of classical physics.

Becquerel's first experiments in 1896

It was in 1896 that French physicist Henri Becquerel made a fortuitous but capital discovery. By studying the phosphoroscence of uranium salts under the X-ray effect, Becquerel placed uranium salts on a photographic plate wrapped in black paper to protect the plate from light. To his surprise, even without exposure to light, the plate had been impressed by some kind of invisible radiation. This unexpected observation showed that uranium spontaneously emitted rays capable of crossing the paper and blackening the plate, a sign of an unknown energy emission. Becquerel had discovered a natural phenomenon which he later baptized « radioactivity », a term popularized by Marie Curie who continued this research.

The discovery of radioactivity by Henri Becquerel in 1896 marked the beginning of a new scientific era, revealing an internal energy to the chemical elements. This phenomenon would not only revolutionize atomic physics, but also open up multiple fields of application, from medicine to energy production. The study of radioactivity is still a source of inspiration and scientific innovation, demonstrating the importance of careful observation and curiosity in the progression of knowledge.