Radioactivity - Artificial and Natural

"O A D I O A C T I V I T Y is a world-famous word relating to a worldfamous subject. In general, when a statement of this sort is spoken, it is more than likely to be foolish; for specialists are altogether too addicted to imagining that their special interests are of world-wide concern when perhaps not fifty thousand people have even heard of them. With respect to radioactivity, though, the statement is correct. It would have been difficult indeed for any literate person to miss making the acquaintance of this word, in any year since 1900. I might say that radioactivity has been the best-advertised topic in modern physics--and this is not to say that it has been over-advertised! It is in fact the only part of modern physics which has received something approaching its due renown. Such good fortune cannot of course be altogether due to the fundamental values of the subject. A great part of the fame of radioactivity comes from medical applications and even more from medical hopes, and some from incidental things, such as the tragic end of one of its great students and the sex of two others. Still it is a matter for rejoicing that whatever the reasons may be, one portion of physics now enjoys its proper quota of the glory to which so many others are entitled. The discovery of radioactivity took place in 1896. Quite a number of things of the highest importance to physics--and to humanity at large--were begun between 1895 and 1900, and of these the study of radioactivity was the second.