Wilhelm Conrad Röntgen was born on March 27, 1845, and died on February 10, 1923. He was a German scientist who discovered and studied a type of radiation called X-rays, which are also known as "Röntgen rays" in many languages. In 1901, Röntgen received the first Nobel Prize in Physics for his discovery of X-rays. A chemical element called roentgenium was named after him to honor his contributions to science.

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 did not have citizenship in any country.

In 1862, Röntgen enrolled at Utrecht Technical School and studied there 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 required qualifications. He then moved to Switzerland and passed an entrance exam at 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) and later held the physics chair at the University of Würzburg. In 1900, he 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 job at Columbia University in New York City and bought tickets to cross the Atlantic. However, World War I began, and he changed his plans. He stayed in Munich for the rest of his career.

After World War I, inflation caused Röntgen to go 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, in his laboratory at the Physical Institute of the University of Würzburg, Röntgen studied the effects of electricity passing through different types of glass tubes used 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 aluminum from the strong electric field that creates the rays. Röntgen 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 wondered if a similar effect might happen with a different type of tube, the Crookes–Hittorf tube, which had thicker glass walls.

On the afternoon of November 8, 1895, Röntgen tested his idea. He made a black cardboard cover like the one on Lenard’s tube and covered the Crookes–Hittorf tube with it. He connected electrodes to an induction coil to create an electric charge. Before testing the screen, he darkened the room to check if his cardboard blocked light. When he sent the charge through the tube, he confirmed the cover was light-tight and prepared for the next step. Then, he saw a faint glow from a bench a few feet away. He repeated the experiment several times and saw the same glow. When he lit a match, he realized the glow came from the barium platinocyanide screen he had planned to use next.

Röntgen called the glowing effect "rays" because it cast regular shadows. Since November 8 was a Friday, he repeated his experiments over the weekend and made notes. In the following weeks, he worked in his lab day and night, studying the new rays, which he temporarily called "X-rays" using the letter "X" for something unknown. In German and some other languages, the word for X-rays 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 during a discharge, he saw his own skeleton glowing faintly on the barium platinocyanide screen.

About six weeks after his discovery, Röntgen took a picture (a radiograph) 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 December 28, 1895. On January 5, 1896, an Austrian newspaper reported his discovery of a new type of radiation. 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 previously shown that some cathode rays could pass through thin metal films. Röntgen wrote three papers about X-rays between 1895 and 1897.

Röntgen’s research excited scientists worldwide. It inspired Henri Becquerel to study connections between X-rays and phosphorescence, leading to his discovery of spontaneous radioactivity in 1896. Marie and Pierre Curie also studied X-rays but later focused on radioactive elements after learning of Becquerel’s findings.

Röntgen was awarded the 1901 Nobel Prize in Physics for discovering the rays named after him. He avoided giving a Nobel lecture and refused to patent his discovery, believing X-rays should benefit society as a whole.

Personal life

Röntgen married Anna Bertha Ludwig in 1872, and they remained together for 47 years until her death in 1919 at the age of 80. They first met in 1866 in Zurich at Anna's father's café, Zum Grünen Glas. They became engaged in 1869 and married in Apeldoorn, Netherlands, on July 7, 1872. The wedding was delayed because Anna was six years older than Wilhelm and his father did not approve of her age or her family's background. At the start of their marriage, they faced financial challenges because Röntgen's family no longer provided support. They had one child, Josephine Bertha Ludwig, whom they adopted when she was 6 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 gave the name roentgenium (Rg) to element number 111 in honor of him. The IUPAP accepted 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 group that does not make money maintains his laboratory and offers guided tours to the Röntgen Memorial Site.

World Radiography Day is an event held every year to show the importance of medical imaging in healthcare. It takes place on 8 November, the same day as the anniversary of Röntgen's discovery. The event was first started in 2012 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 released to honor Röntgen for discovering 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.