X-rays were discovered in 1895 by Wilhelm Roentgen, a discovery that was to bring him the first Nobel Prize for physics. (No, I'm not really going to trespass on Marcus's territory! Well, not for long.) Like many other scientists of the time, Roentgen was experimenting with electtrifying the thin gases in vacuum tubes. One night he noticed that a fluorescent screen at one end of his lab glowed each time he ran a current through his vacuum tube. The screen continued to glow when Roentgen placed sheets of card, copper, or aluminium between tube & scrreen, but stopped when these were replaced by lead. This must have been startling enough, but he must really have been blown away to see the bones of his hand show up on the screen when his hand passed through the invisible rays emitted from the electrified vacuum tube. Roentgen had discovered X-rays.
Today X-rays are used in a wide range of applications. The structure of DNA was elucidated through X-ray diffraction photographs. Airport security systems use them to detect various proscribed items in travellers' baggage. (Recent developments in this area have led to concerns that customs officers might see more of a traveller than modesty might permit.) And of course there are the medical applications of X-rays, along with their more sophisticated spin-off, the CT (or computerised tomography) scan. CT scans are a signifcant medical tool, but they've also allowed scientists to examine some truly ancient indiviuals: CT scans of a Homo floresiensis cranium have been used to build a 'virtual endocast' that models the indivdiual's brain & has been used to attempt to determine its affinities.
And where is this heading? Well, I now have a lovely X-ray of my left foot that shows very clearly what happens when your little toe connects at speed with a door jamb. The proximal phalanx of my little toe (that's the toe bone closest to the bones of the foot itself) is in 2 quite distinct parts. Ouchy ouch ouch! I must wear a moon shoe for the next few weeks,and the dog is Not Pleased. Not pleased at all.