Rontgen, Wilhelm Conrad - born March 27, 1845, Lennep, Prussia [now Remscheid, Ger.] d. Feb. 10, 1923, Munich - German physicist who was a recipient of the first Nobel Prize for Physics, in 1901, for his discovery of X rays, which heralded the age of modern physics and revolutionized diagnostic medicine.

Rontgen studied at the Polytechnic in Zürich and then was professor of physics at the universities of Strasbourg (1876-79), Giessen (1879-88), Wurzburg (1888-1900), and Munich (1900-20). His research also included work on elasticity, capillary action of fluids, specific heats of gases, conduction of heat in crystals, absorption of heat by gases, and piezoelectricity.

In 1895, while experimenting with electric current flow in a partially evacuated glass tube (cathode-ray tube), Röntgen observed that a nearby piece of barium platinocyanide gave off light when the tube was in operation.

He theorized that when the cathode rays (electrons) struck the glass wall of the tube, some unknown radiation was formed that traveled across the room, struck the chemical, and caused the fluorescence.

Further investigation revealed that paper, wood, and aluminum, among other materials, are transparent to this new form of radiation. He found that it affected photographic plates, and, since it did not noticeably exhibit any properties of light, such as reflection or refraction, he mistakenly thought the rays were unrelated to light.

In view of its uncertain nature, he called the phenomenon X-radiation, though it also became known as Rontgen radiation.

He took the first X-ray photographs, of the interiors of metal objects and of the bones in his wife's hand.

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A new form of radiation was discovered in 1895 by Wilhelm Roentgen, a German physicist. He called it X-radiation to denote its unknown nature. This mysterious radiation had the ability to pass through many materials that absorb visible light. X-rays also have the ability to knock electrons loose from atoms. Over the years these exceptional properties have made X-rays useful in many fields, such as medicine and research into the nature of the atom.

Roentgen was working in his laboratory at the Physical Institute of the University of Würzburg, Germany, experimenting with a Crookes tube.

The news spread rapidly through out the world. As early as February 8, 1896, X-rays were being used clinically the United States. in Dartmouth, Massachusetts when Edwin Brant Frost produced a plate of a Colles fracture in a man named Eddie McCarthy for his brother, Dr. Gilman Dubois Frost.

Eventually, X-rays were found to be another form of light. Light is the by-product of the constant jiggling, vibrating, hurly-burly of all matter.

Like a frisky puppy, matter cannot be still. The chair you are sitting in may look and feel motionless. But if you could see down to the atomic level you would see atoms and molecules vibrating hundreds of trillions of times a second and bumping into each other, while electrons zip around at speeds of 25,000 miles per hour.

When charged particles collide--or undergo sudden changes in their motion--they produce bundles of energy called photons that fly away from the scene of the accident at the speed of light. In fact they are light, or electromagnetic radiation, to use the technical term. Since electrons are the lightest known charged particle, they are most fidgety, so they are responsible for most of the photons produced in the universe.

The speed of the particles when they collide or vibrate sets a limit on the energy of the photon. The speed is also a measure of temperature. (On a hot day, the particles in the air are moving faster than on a cold day.)

Very low temperatures (hundreds of degrees below zero Celsius) produce low energy radio and microwave photons, whereas cool bodies like ours (about 30 degrees Celsius) produce infrared radiation. Very high temperatures (millions of degrees Celsius) produce X-rays.

The photons themselves can also collide with electrons. If the electrons have more energy than the photons, the collision can boost the energy of the photons. In this way, photons can be changed from low-energy photons to high-energy photons. This process, called Compton scattering, is thought to be important around black holes, where matter is dense and has been heated to many millions of degrees.

The photons collected in space by X-ray telescopes reveal the hot spots in the universe--regions where particles have been energized or raised to high temperatures by gigantic explosions or intense gravitational fields.

Synchrotron Radiation

But this is not the whole story. X-ray photons can also be created under different conditions. When physicists were operating the first particle accelerators, they discovered that electrons can produce photons without colliding at all. This was possible because the magnetic field in the accelerators was causing the electrons to move in large spirals around magnetic field lines of force. This process is called synchrotron radiation.

In the cosmos particles such as electrons can be accelerated to high energies– near the speed of light– by electric and magnetic fields. These high-energy particles can produce synchrotron photons with wavelengths ranging from radio up through x-ray and gamma-ray energies.