Wilhelm Conrad Rontgen was the first scientist to recognize the phenomenon of X rays (which he so-named for their mysterious properties, such as the ability to penetrate solid objects such as human skin). Other scientists were certainly exposed to X rays, as Rontgen discovered them while conducting fairly commonplace research on the cathode rays emitted by a crookes tube, but none noticed their peculiar effects. For this discovery, which established the field of radiology (the application of X rays for medical diagnosis), Rontgen received the first Nobel Prize in physics in 1901.
Rontgen was born on March 27, 1845, in Lennep im Bergischen, Prussia (now part of Remscheid, Germany). He was the only son of Charlotte Constanze Frowein and Friedrich Conrad Rontgen, a cloth manufacturer and merchant. When Rontgen was three, the family moved to Apeldoorn, Holland, where he attended the Institute of Martinus Herman van Doorn. Rontgen entered the Utrecht Technical School in December 1862, but after about two years, he acted as the fall guy for a fellow student who caricatured an unpopular teacher, resulting in Rontgen’s expulsion from school. Unfortunately, his sacrifice cost him dearly, as the University of Utrecht refused him admittance as a regular student, relenting in January 1865 by admitting him as an "irregular" student.
In November 1865, Rontgen transferred to the Swiss Federal Institute of Technology in Zurich, which admitted him as a "regular" student in mechanical engineering. He earned his diploma in August 1868, and, at the suggestion of his physics professor, August Kundt, he remained at the institute for graduate work in physics, not engineering. He wrote his doctoral dissertation on "Studies about Gases" to earn his Ph.D. in 1869. At about this time, he met Anna Bertha Ludwig, the daughter of a German revolutionary in exile in Zurich, and the couple married on January 19, 1872. They had no children together, but they adopted Ludwig’s six-year-old niece, Josephine Bertha, in 1887.
Wilhelm Conrad Rontgen was the first scientist to recognize the phenomenon of X rays.
After earning his doctorate, Rontgen maintained his relationship with Kundt by serving as his assistant, first in Zurich, then moving with his mentor to the University of Wurzburg in Germany in 1871. After two years there, Rontgen again relocated to remain with Kundt, this time to France’s newly established University of Strasbourg, which appointed him as a privatdozent. In 1875, he struck out on his own to serve as professor of physics and mathematics at the Agricultural Academy of Hohenheim, but within a year, he returned to the superior research facilities at Strasbourg, where he was promoted to the rank of associate professor of physics.
In 1879, Rontgen finally broke ranks with Kundt to accept a full professorship at the German University of Giessen in Hesse, where he remained for the next decade. In 1888, his last year there, he published a paper reporting what he considered his most important discovery: an experimental confirmation of james clerk maxwell’s theory of electromagnetism. Henry Rowland claimed to have created a magnetic effect of electrostatic charges in motion in 1875, but none could repeat his results until Rontgen did so. In recognition, Hendrik Lorentz dubbed the phenomenon the "rontgen current."
In 1888, Rontgen returned to the University of Wurzburg (which had previously refused him an academic appointment for lack of acceptable credentials) as a professor of physics and director of its Physical Institute. In 1894, the university appointed him as its rector, though he continued to conduct research on top of his administrative responsibilities.
In 1895, Rontgen was investigating the cathode rays emitted by a Crookes tube, a popular line of research at the time, although it was outside of his own specialty. On Friday, November 8, he darkened his laboratory and covered the tube in black cardboard; to his surprise, he noticed some barium platinocyanide crystals on a screen all the way across the room glowing when he turned on the apparatus. The chemical plate continued to luminesce even when he moved it into the next room, convincing Ront-gen that he was observing not cathode rays, which travel only a few centimeters, but a wholly different, much stronger phenomenon.
Rontgen spent the next seven weeks confirming the extraordinary properties of this previously undiscovered effect. These X strahlen, or X rays (as he named them after their mysterious nature), traveled in straight lines as far as two meters, passed through glass and wood but not~20 metal, and could not be refracted, reflected or deviated by magnetism. They could also expose photographic plates, and Rontgen took photos of balance weights enclosed in a box, the chamber of a shotgun, and, most famously, the bones of his wife’s hand. It was this last picture, taken on December 22, that captured the world’s imagination when the popular press carried word of his discovery on January 6, 1896.
A week later, the kaiser summoned Rontgen to demonstrate X rays before the royal court, immediately earning the physicist the Prussian Order of the Crown, Second Class (though he refused to use the "von" title before his name). Rontgen himself followed up on his discovery with surprisingly little attention, writing only three papers on X rays, and declining to patent the discovery, preferring to allow free use of the innovation. However, the scientific community followed up on his discovery with intense activity, as antoine-henri becquerel discovered radioactivity later in 1896 while conducting X-ray studies.
The scientific community also followed up on Rontgen’s discovery of X rays by honoring him with numerous awards, including the 1896 Rumford Medal of the Royal Society, the Royal Order of Merit of Bavaria and the Baumgaertner Prize of the Vienna Academy that same year, the 1897 Elliott-Cresson Medal of the Franklin Institute, and the 1900 Barnard Medal of Columbia University. Most significantly, the Royal Swedish Academy of Science granted Rontgen the first Nobel Prize in physics in 1901.
In 1900, the Bavarian government requested that Rontgen move from Wurzburg to fill a similar position at the University of Munich as professor of physics and director of its Physical Institute, a position he retained until grief over his wife’s 1919 death forced him to retire in 1920. The inflation in the wake of World War I bankrupted Rontgen, who died from intestinal cancer on February 10, 1923.
