An Accident That Changed the World: The Discovery of X-Rays

In the fall of 1895, physicist William Conrad Roentgen, Rector at the University of Würzburg,  was studying cathode rays in his laboratory. In the course of his experiments, he noticed that a screen set at some distance from the tubes he was studying was glowing. All previous research had indicated that cathode rays could not maintain their power to produce florescent light at that much distance. Fascinated, he locked himself away in his lab and began to experiment with the new rays. 1

These strange new rays could not be refracted with water, nor could he concentrate them by standard methods. He found that the rays could pass through thick layers of rock salt, electrolytic salt powder and zinc dust, unlike visible light. He concluded that these unusual rays were not susceptible to regular refraction or reflection. Unlike cathode rays, they were also unsusceptible to magnetic deflection. His experiments demonstrated that these rays produced a mysterious light that could pass through most substances but leave shadows of solid objects. He called them ‘X-Rays’ because X stood for ‘unknown’. 2

Three days before Christmas he brought his wife into the laboratory and they emerged with a photograph of the bones in her hand and the ring on her finger. He published the photograph on the 28th of December and by the 16th of January in 1896, the New York Times announced the discovery of a ‘new form of photography, which revealed hidden solids, penetrated wood, paper and flesh and exposed the bones of the human frame’. Within a month of Roentgen’s announcement, doctors were using X-rays to locate bullets in human flesh and photograph broken bones. 3

Roentgen’s accidental discovery of X-rays paved the way for the development of today’s broad spectrum of imaging techniques including magnetic resonance imaging (MRI), computer tomography (CT), ultrasound and echocardiography, among others.

Rontgen received the Nobel Prize for Physics in 1901. He never sought honors or financial profit for his research. He rejected a title that would have given him entry into German nobility and donated his Prize money to his university. Roentgen never patented his discovery to ‘ensure that the world could freely benefit from his work’. He was nearly bankrupt at the time of his death due to inflation following World War I. 4 

Photo from Google Photos

Content Sources:

  1. ‘Early History of X Rays’, Alexi Assumes, Beem Line Summer, 1995
  2. ‘History of Medicine: Dr. Roentgen’s Accidental X-Rays’,
  3. Ibid source 1
  4. ‘November 8, 1895: Roentgen’s Discovery of X-Rays’, American Physical Society, APS News November 2001 (Volume 10, Number 10)