More than one hundred years ago, Henri Becquerel discovered that uranium emitted penetrating rays similar to those used by Wilhelm Röntgen to take the first X-ray image (of his wife’s hand), starting ...

It took many more years for other scientists to discover the true nature of Becquerel’s discovery: radioactivity. Radioactivity is the process, often called radioactive decay, by which an unstable ...

Timothy J. Jorgensen does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations ...