Picture of Wilhelm Roentgen Courtesy of The Bettmann Archive

Wilhelm Roentgen was a German physicist who lived between 1845-1923. His accidental discovery of x-rays in 1895 changed the fields of physics and medicine.

X-rays are a type of radiation which can penetrate materials that ordinary light cannot. They allow us to "view" the insides of objects (like a human body) without having to open them. Today, we use x-rays to locate bone fractures and breaks, cancerous tumors, and tooth cavities.

For his brilliant experimental work, Roentgen received the first Nobel Prize, in 1901.