Wilhelm Conrad Röntgen was born on March 27, 1845, and died on February 10, 1923. He was a German scientist who studied how things work through experiments. He discovered a type of invisible light called X-rays, which are also known as "Röntgen rays" in many languages. In 1901, Röntgen received the first Nobel Prize in Physics for discovering X-rays. A chemical element named roentgenium was later named in his honor.
Biography
Wilhelm Conrad Röntgen was born on 27 March 1845 in Lennep (now part of Remscheid), Prussia. He was the only child of Friedrich Conrad Röntgen, a merchant and cloth manufacturer, and Charlotte Constanze Frowein. In 1848, he moved with his parents to the Netherlands, where his mother’s family lived. This move made him stateless, meaning he had no official country to belong to.
In 1862, Röntgen enrolled at Utrecht Technical School, where he studied for nearly two years. In 1865, he was unfairly expelled from the school after being falsely accused of drawing a caricature of a teacher. The drawing was actually made by someone else.
Without a high school diploma, Röntgen could not attend university in the Netherlands as a regular student. In 1865, he tried to study at Utrecht University without the proper qualifications. He then moved to Switzerland and passed the entrance exam for the Federal Polytechnic School in Zurich (now ETH Zurich), where he studied mechanical engineering. In 1869, he earned his Ph.D. from the University of Zurich. At the university, Röntgen was a favorite student of Professor August Kundt. After graduating, he followed Kundt to the University of Würzburg and later to the University of Strassburg in 1873.
In 1874, Röntgen became a lecturer at the University of Strassburg. The next year, he became a professor at the Academy of Agriculture in Hohenheim. In 1876, he returned to Strassburg as a professor of physics. In 1879, he was appointed to the physics chair at the University of Giessen. In 1888, he regained German citizenship after being stateless for 40 years. He then received the physics chair at the University of Würzburg and, in 1900, was asked by the Bavarian government to take the physics chair at the University of Munich.
Röntgen had family in Iowa, United States, and planned to move there. He accepted a position at Columbia University in New York City and purchased tickets to travel across the Atlantic. However, the start of World War I changed his plans, and he stayed in Munich for the rest of his career.
Because of the inflation after World War I, Röntgen faced financial difficulties and went bankrupt. He spent his final years at his countryside home in Weilheim.
Röntgen died of colorectal cancer on 10 February 1923 in Munich at the age of 77. As stated in his will, most of his personal and scientific letters were destroyed after his death. His will also included donations to his hometown of Lennep and the Physical Institute of the University of Würzburg.
Discovery of X-rays
In 1895, Röntgen worked in his lab at the University of Würzburg. He studied the effects of electricity passing through different vacuum tubes made by scientists like Heinrich Hertz, Johann Hittorf, William Crookes, Nikola Tesla, and Philipp Lenard. In early November, he repeated an experiment using one of Lenard’s tubes, which had a thin aluminum window to let cathode rays escape and a cardboard cover to protect the window from damage. He knew the cardboard blocked light, but he noticed that the invisible cathode rays made a small cardboard screen painted with barium platinocyanide glow when placed near the aluminum window. He thought the thicker-walled Crookes–Hittorf tube might also cause this glowing effect.
On 8 November 1895, Röntgen tested his idea. He built a black cardboard cover like the one on Lenard’s tube and covered the Crookes–Hittorf tube. He connected electrodes to an induction coil to create an electric charge. Before testing, he darkened the room to check if the cardboard blocked light. When he passed the charge through the tube, he confirmed the cover was light-tight. Then, he noticed a faint shimmer from a bench nearby. After repeating the test, he saw the same shimmer. Using a match, he found the glow came from the barium platinocyanide screen he had planned to use next.
Röntgen called the glowing effect "rays" because it formed clear shadows. Since 8 November was a Friday, he repeated the experiment over the weekend and made notes. In the following weeks, he worked in his lab, studying the new rays, which he temporarily called "X-rays" using the letter "X" for something unknown. In German and some Central and Eastern European languages, the word for X-ray comes from Röntgen’s name, and the images are called "Röntgenograms."
During his experiments, Röntgen tested how different materials blocked the rays. When he placed a small piece of lead near the tube, he saw the first radiographic image: his own skeleton glowing on the screen.
About six weeks after his discovery, Röntgen took a picture of his wife Anna Bertha’s hand using X-rays. When she saw her skeleton, she said, "I have seen my death!" Later, he took a clearer image of his friend Albert von Kölliker’s hand during a public lecture.
Röntgen published his findings in a paper titled Ueber eine neue Art von Strahlen (On a New Kind of Rays) on 28 December 1895. An Austrian newspaper reported his discovery on 5 January 1896. He was honored with an honorary M.D. from the University of Würzburg and received the Rumford Medal from the Royal Society in 1896, shared with Philipp Lenard, who had shown that some cathode rays could pass through thin metal films. He wrote three papers on X-rays between 1895 and 1897.
Röntgen’s work excited physicists worldwide. It inspired Henri Becquerel to study connections between X-rays and phosphorescence, leading to his discovery of radioactivity in 1896. Marie and Pierre Curie were also influenced by X-ray research but shifted their focus after learning of Becquerel’s findings, eventually identifying radioactive elements.
In 1901, Röntgen received the Nobel Prize in Physics for discovering the rays named after him. He declined to give a Nobel lecture and refused patents for X-rays, believing the discovery should benefit society.
Personal life
Röntgen married Anna Bertha Ludwig in 1872. They were married for 47 years until Anna passed away in 1919 at the age of 80. In 1866, they met in Zurich at Anna's father's café called Zum Grünen Glas. They became engaged in 1869 and married in Apeldoorn, Netherlands, on July 7, 1872. The marriage was delayed because Anna was six years older than Wilhelm, and Wilhelm's father did not approve of her age or her simple background. They faced financial challenges early in their marriage because family support for Röntgen had stopped. They had one child, Josephine Bertha Ludwig, whom they adopted when she was six years old after her father, Anna's only brother, died in 1887. Röntgen was a member of the Dutch Reformed Church.
Commemoration
In November 2004, the IUPAC named element number 111 roentgenium (Rg) in his honor. The IUPAP agreed to use the name in November 2011.
A collection of Röntgen's papers is kept at the National Library of Medicine in Bethesda, Maryland.
Today, in Remscheid-Lennep, 40 kilometers east of Röntgen's birthplace in Düsseldorf, is the Deutsches Röntgen-Museum.
In Würzburg, where Röntgen discovered X-rays, a non-profit organization keeps his laboratory and offers guided tours to the Röntgen Memorial Site.
World Radiography Day is an annual event that highlights the importance of medical imaging in healthcare. It is celebrated on November 8 each year, matching the anniversary of Röntgen's discovery. The event began in 2012 as a joint effort by the European Society of Radiology, the Radiological Society of North America, and the American College of Radiology.
As of 2023, 55 stamps from 40 countries have been made to honor Röntgen as the discoverer of X-rays.
Röntgen Peak in Antarctica is named after Wilhelm Röntgen.
Minor planet 6401 Roentgen is named after him.
In 2010, Röntgen's discovery was celebrated in a Google doodle.