|Henri Becquerel, Marie Curie, Pierre Curie, Ernest Rutherford, Frederick Soddy physics|
A crust of phosphorescent uranium salt darkens a photographic plate when left out in the sun and when moved to a dark drawer continues to darken the photographic plate. Henri Becquerel thought that rays of longer duration continued to be emitted from the excited material. Becquerel compared this effect to the effects of the X-rays studied by Röntgen. Within two months Becquerel tested non-phosphorescent uranium salt and correctly concluded that uranium spontaneously emitted radiation.
They didn’t know, back then, that radiation could kill you, that ionizing rays can knock loose the rungs of DNA upon which the production of new blood cells depends. Wilhelm Röntgen took precautions against the unknown, but Marie Curie died of aplastic anemia; her bone marrow could not adequately replenish her red blood cells. Today, Marie’s papers are kept in lead-lined boxes and you need a lead-lined suit to read them.
Transmutation of elements
Ernest Rutherford and Frederick Soddy showed that radioactivity occured when atoms spontaneously disintegrated into other types of atoms. Rutherford was the first person to deliberately change one element into another. He bombarded pure nitrogen with alpha particles to convert nitrogen to oxygen. Transmutation of elements was the goal of alchemissts, including Newton, for four millennia. Little had they realized that unleashing atomic forces would bring so much destruction upon the world.