X-rays Were a Life-Saving Accident

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The groundbreaking discovery that allows doctors to peer inside our bodies and astronomers to probe the mysteries of space was announced on this day 129 years ago.

Wilhelm Röntgen, a German physicist, accidentally discovered X-rays in 1895 while tinkering in his laboratory. At the time, scientists were fascinated by the then-elusive dynamics of electricity. Röntgen had wondered whether streams of electrons called cathode rays, produced in charged glass containers called cathode ray tubes, could move through glass.

He had covered his cathode ray tube with thick black cardboard, but he noticed that a green glow was seeping through and projecting onto a fluorescent screen in his laboratory. This strange phenomenon persisted even when the receiving surface was more than 6 feet from the tube.

Röntgen sent the rays through objects of varying thickness and observed that they exhibited different degrees of transparency to this light when recorded on a photographic plate. He named them X-rays, with X referring to “unknown.”

On January 5, 1896, the Austrian newspaper The Press announced the news of this revelation. The article “was hastily written by the editor in journalistic style and contained no information on the nature of the new rays,” according to an article published in the Journal of the Belgian Society of Radiology. Two days later, However, The Press published another article with more details about the discovery.

Read more: “Discovering the expected”

Shortly after his first X-ray experiments, Röntgen learned that his rays could pass through human tissue to illuminate bones there. He captured the bones in the hand of his wife, Anna Bertha Ludwig. “I saw my death,” she said at the time. Röntgen noticed that the skin around his bones had a paler shade because it was more permeable to the rays.

In subsequent experiments, German physicist Max von Laue and his students demonstrated that X-rays “are of the same electromagnetic nature as light, but differ from it only in the higher frequency of their vibration,” according to the Nobel Prize organization.

Less than a year after Röntgen’s first eureka, doctors in the United States and Europe have incorporated this new technique into their work. In 1901, Röntgen received, among other awards, the first Nobel Prize in physics, and several cities named streets after him. Yet he “retained the characteristics of a surprisingly modest and reticent man,” notes the Nobel Prize organization. In fact, Röntgen never filed a patent and declared that “his inventions and discoveries should belong to humanity.”

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Main image: Internet Archive Book Images / Wikimedia Commons

• Molly Glick

  Published on January 5, 2026

  Molly Glick is the newsletter editor of Nautilus.