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Did you know that the technology behind the X-ray machine, a foundation of modern medicine, was “accidentally” discovered nearly 122 years ago on November 8, 1895, by Wilhelm Conrad Röntgen? The breakthrough of X-rays can be accredited as a milestone in physics as well as in medical sciences. It unravelled many of the mysteries of physics but it’s effects resonated far beyond that.

In this article, we’ll look at how X-ray was discovered, what it does and how it changed the face of medicine.


Accidental Discovery in Germany

In late 1895, W. C. Roentgen, German physicist, was working with a cathode ray tube (similar to our fluorescent light bulbs) in his laboratory. He evacuated the tube of all air, filled it with a special gas, and passed a high electric voltage through it. When he did this, the tube would produce a fluorescent glow. Roentgen shielded the tube with heavy black paper and found that a green colored fluorescent light could be seen coming from a screen setting a few feet away from the tube. He realized that he had produced a previously unknown “invisible light,” or ray, that was being emitted from the tube; a ray that was capable of passing through the heavy paper covering the tube. Through additional experiments, he also found that the new ray would pass through most substances casting shadows of solid objects on pieces of film. He named the new ray X-ray because in mathematics “X” is used to indicated the unknown quantity.

What are X-rays?

X-rays themselves are a form of electromagnetic radiation, composed of the same photons as visible light, microwaves, and radio waves, only vibrating at much shorter wavelengths and much higher frequencies. This enables them to penetrate solid objects, such as wood, clothing and human tissues.

When a medical X-ray image is created, an X-ray beam passes through the patient and is picked up by a detector on the other side. Portions of the beam are absorbed, but others pass all the way through, and the “shadows” cast by different tissues create the image. Perhaps the most notable of all objects revealed by X-rays has been the human body itself.

Almost immediately after the discovery of the new rays, scientists and physicians began using them to peer inside the body without cutting it open, revealing not only normal structures but also fractures, pneumonia and even foreign objects, such as swallowed coins.

X-Rays Timeline

1897: X-rays first used on a military battlefield, during the Balkan War, “to find bullets and broken bones inside patients.”

1901: X-ray scientist Wilhelm Conrad Röntgen receives the first Nobel Prize in physics. Although he received a lot of recognition, he never tried to patent his discovery.

1904: A man who worked extensively with X-rays, Clarence Dally, Thomas Edison’s assistant, dies of skin cancer. His death causes scientists to take the radiation risks involved with X-rays more seriously, although they are not fully understood.

1930s to 1950s: American shoe stores use shoe-fitting fluoroscopes, using X-rays to let customers see the bones in their feet, as a gimmick to ensure a proper “fit”. The practice ended in the 1950s when it was determined to be too risky for health reasons due to the radiation.

Interesting Facts

  • US President James Garfield died in 1881 largely because his doctors could not locate an assassin’s bullet in his body, while a century later, X-rays revealed the bullet in President Ronald Reagan’s chest in minutes, helping to save his life.
  • X-ray astronomy was impossible until the 1960s, but thanks to rocket- and satellite-mounted detectors, astronomers began detecting high-energy X-ray emissions from long-visible stars and galaxies. Today, even truly bizarre objects such as neutron stars and black holes, which have densities more than trillions of times that of the sun can be detected through X-ray astronomy.
  • Newer medical imaging techniques such as CT scanning rely on Roentgen’s discovery.
  • One of Roentgen’s first experiments late in 1895 was a film of his wife Bertha’s hand with a ring on her finger. When she saw the picture, she said “I have seen my death.” Look at that X-ray below.


So, thanks to Roentgen’s invisible light, we now operate with a much deeper understanding of the universe we inhabit, the molecules and cells of which we are composed and the diseases that threaten our lives.

Roentgen himself would no doubt be astounded by the novel purposes to which X-rays have been adopted in the decades since his death. Yet he would also remind us that, over the next 120 years, many new X-ray discoveries almost certainly remain to be made.

You may also like:

6 Accidental Discoveries that Forever Changed the World

Inventions of Nikola Tesla We Use in Everyday Life

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