Röntgen's X-ray: the physicist who saw bones through skin

On the evening of 8 November 1895, Wilhelm Röntgen, a German physicist at the University of Würzburg, was experimenting with cathode rays in a darkened laboratory. He had covered a Crookes-Hittorf tube with black cardboard to block visible light. When he energised the tube, he noticed a faint shimmer from a fluorescent screen several feet away — a screen coated with barium platinocyanide that he had intended to use later. The screen was glowing even though the tube was fully covered. Röntgen did not know what kind of ray was causing it, so he called it an 'X-ray' — X for the unknown.

Röntgen spent the next several weeks living in his laboratory, eating and sleeping there as he investigated the properties of the mysterious rays. He discovered that they could pass through most materials — paper, wood, even human tissue — but were blocked by bone and metal. On 22 December 1895, he took the first X-ray photograph: the hand of his wife Anna Bertha Ludwig. When she saw the bones of her own hand and her wedding ring, she reportedly exclaimed, 'I have seen my death!'

Röntgen published his findings on 28 December 1895 in a paper titled 'Ueber eine neue Art von Strahlen' (On a New Kind of Ray). The news spread rapidly. An Austrian newspaper reported the discovery on 5 January 1896, and within weeks, scientists around the world were replicating the experiment. Röntgen was awarded the first Nobel Prize in Physics in 1901. He refused to patent the discovery, insisting that X-rays should benefit everyone freely.

X-rays revolutionised medicine almost overnight. For the first time, doctors could see inside a living body without cutting it open. The discovery also inspired Henri Becquerel to investigate the connection between X-rays and phosphorescence, leading to his discovery of radioactivity in 1896 — and Marie Curie's subsequent work. X-rays remain one of the most important diagnostic tools in medicine, with applications in radiology, oncology, and industrial inspection. The World Day of Radiology is celebrated on 8 November, the anniversary of Röntgen's accidental discovery.