Working late in his laboratory at the University of Würzburg, physicist Wilhelm Conrad Röntgen observed that a screen coated with fluorescent material glowed even when shielded from a cathode-ray tube by black cardboard. He called the mysterious radiation "X-rays." Within weeks he produced an image of his wife's hand, bones and wedding ring visible through flesh, and the discovery spread across the scientific world almost instantly.
Röntgen was alone in his lab on the evening of November 8, 1895, testing whether cathode rays could penetrate glass, when he noticed a faint green shimmer on a nearby screen coated with barium platinocyanide. The cathode-ray tube was completely covered in black cardboard, so no visible light could have caused it. Puzzled, he moved the screen farther away; the glow persisted. Something invisible was passing through the cardboard and traveling across the room.
Röntgen spent the next seven weeks in near-total secrecy, eating and sleeping in his lab, testing what this radiation could and could not pass through. Wood, paper, and flesh proved transparent to it; bone and metal did not. When he finally photographed the bones of his wife Anna Bertha's hand, her wedding ring clearly visible, she reportedly said, "I have seen my death."
He published his findings on December 28, 1895, and the effect was immediate and global. Newspapers ran the hand photograph within days, and physicians began using X-rays for diagnosis before anyone understood the biological risks. Röntgen refused to patent his discovery, believing it belonged to humanity, and in 1901 became the first-ever recipient of the Nobel Prize in Physics.
Key people: Wilhelm Röntgen, Anna Bertha Röntgen