Wilhelm Conrad Röntgen

Wilhelm Conrad Röntgen was born on March 27, 1845, in Lennep in the Prussian Rhineland (now part of Remscheid, Germany); he was a Protestant.⁠[1][2]

Lennep was a town with a long tradition of cloth making; he came from a family of cloth makers and spent his first years there.⁠[3][4]

His father, Friedrich Conrad Röntgen (1801–1884), was a merchant and cloth manufacturer in Lennep and later in Apeldoorn; his mother, Charlotte Constanze (1806–1888), was born Frowein.⁠[2][5]

His paternal grandfather, Johann Heinrich Röntgen (1759–1842), was a cloth manufacturer and coppersmith in Lennep, and his paternal grandmother was Anna Louise Frowein (1773–1844); his maternal grandfather, Johann Wilhelm Frowein (1775–1860), was a merchant in Amsterdam and Anna Louise’s brother.⁠[2]

The family probably shared seventeenth-century ancestors with Abraham Roentgen and David Roentgen, though these cannot be traced in detail.⁠[2]

NDB states that the family moved to Apeldoorn in the Netherlands in 1848, probably for business reasons; the biography published by the Röntgen-Gedächtnisstätte, the Röntgen Memorial in Würzburg, dates the move to 1849.⁠[2][5]

He went to school in Apeldoorn and Utrecht. NDB states that after the local school he attended the technical school (Technische Schule) in Utrecht from 1862; the University of Würzburg’s archives date his time at that school to 1861–1863.⁠[5][2][6]

He left the school without a leaving certificate. NDB states that he was expelled in 1864, probably over a schoolboy prank; the University of Würzburg’s archives say that he was falsely accused of a disciplinary offence; a 2016 press release of the University of Würzburg relates that a drawing mocking a teacher circulated at the school, that it is not certain whether he drew it or refused to name the artist, and that the affair ended with his expulsion in 1863.⁠[2][6][7]

An article in the Pharmazeutische Zeitung likewise attributes the expulsion to a prank, dates it to 1864 and states that the family was then living in Utrecht.⁠[4]

LMU Munich’s article states that he was expelled at 16 or 17, shortly before he was due to sit his school-leaving examinations, because he refused to say who had drawn a caricature of his teacher on the blackboard; Kärin Nickelsen, who holds the chair of the history of science at LMU Munich, points out that this story has not been confirmed and that he may instead have left to start a career in his father’s company.⁠[8]

Utrecht University’s profile states that he did not pass the final examinations of the technical school, a failure that rumour blamed on a teacher who disliked him; unable therefore to sit the university examinations, he enrolled at Utrecht University as a non-examination student in January 1865. NDB states that he failed the Dutch university admission examination.⁠[9][2]

At the end of 1865 he entered the Federal Polytechnic School (Eidgenössisches Polytechnikum) in Zurich, now ETH Zurich. NDB states that study there was possible without an examination; the University of Würzburg’s 2016 press release says that the school accepted candidates without the Abitur if they passed an entrance examination; the Pharmazeutische Zeitung article says that his good marks won him admission. His application was supported by a testimonial from his professor Buys Ballot.⁠[2][5][7][4][9]

He studied mechanical engineering and received his diploma as a mechanical engineer in August 1868. During his studies he attended lectures by Rudolf Clausius (1822–1888) and Gustav Zeuner (1828–1907), among others, then turned entirely to physics and also attended the lectures of August Kundt (1839–1894).⁠[2][6][1]

He received his doctorate in physics from the University of Zurich; the sources give different years. NDB gives 1870, with a dissertation on the theory of gases; the University of Würzburg’s archives, Utrecht University and the Pharmazeutische Zeitung article give 1869, the archives adding that he had never matriculated at the University of Zurich; the Röntgen Memorial’s biography gives 1868 and renders the dissertation’s title in English as Studies on Gases.⁠[1][2][6][9][4][5]

In 1870 he went to Würzburg as Kundt’s unpaid assistant.⁠[2][6]

During his first stay in Würzburg (1870–1872) laboratory equipment was limited, so he acquired practical skills and designed his own experiments, building simple apparatus himself almost without a mechanic’s help; he said that the poor equipment did not harm his precision.⁠[6]

Because he lacked the Abitur, the University of Würzburg would not accept his habilitation, the qualification for teaching at a university.⁠[6][8][4]

In 1872 he followed Kundt to the newly founded Imperial University of Strasbourg (Reichsuniversität Straßburg).⁠[2][5][6]

The same year he married Anna Bertha Ludwig in Apeldoorn. She was the daughter of Johann Gottfried Ludwig, an innkeeper and fencing master to the students in Zurich, and of Elisabeth Gschwend.⁠[1][2]

Under this marriage NDB’s genealogy notes a cousin relationship (Vt., Vetter) with the poet and writer Otto Ludwig (1813–1865).⁠[2]

Having followed Kundt to Strasbourg, he was allowed to complete his habilitation there: NDB dates it to 1873, the University of Würzburg’s archives and the Röntgen Memorial’s biography to 1874.⁠[8][2][6][5]

In 1875 he became full professor of mathematics and physics at the Agricultural Academy (Landwirtschaftliche Akademie) in Hohenheim, where he gained his first teaching experience.⁠[2][6]

In 1876 he returned to Strasbourg as extraordinary professor of physics alongside Kundt, remaining there until 1879.⁠[2][6][10]

With Kundt he studied the electromagnetic rotation of the plane of polarization of light in gases; he also worked on the conduction of heat in crystals.⁠[2]

In 1879 he became full professor of physics at the University of Giessen, holding the chair until 1888; the timeline of the University of Würzburg’s archives places the appointment in 1880. A joint press release of Justus Liebig University Giessen and the city of Giessen in 2023 calls Giessen his “Wahlheimat,” his adopted home.⁠[2][10][11][6]

In Giessen he oversaw the move of the Institute of Physics from Frankfurter Strasse to the new main university building, and he published about twenty scientific papers.⁠[12][5]

His work on the “Röntgenton” showed that gases absorb heat radiation, and in 1888 he demonstrated that a dielectric moving between charged capacitor plates produces a magnetic effect; this magnetic field of a displacement current became known as the “Röntgenstrom.”⁠[11][2][6]

In 1888 he succeeded Friedrich Kohlrausch (1840–1910) as full professor of physics and head of the Institute of Physics at the University of Würzburg, drawn back in part by its more modern and larger physics laboratory. The University of Würzburg’s archives regard this second Würzburg period as very important for his research.⁠[2][6][5]

The same year Utrecht University asked him to succeed Buys Ballot; he declined and stayed in Germany.⁠[9]

In 1893 he was elected rector of the University of Würzburg, serving in 1893–1894.⁠[6][8]

Before the X-rays he studied the properties of quartz and the compressibility of liquids in Würzburg, as well as electrical conduction in gases, especially cathode rays (electrons).⁠[6][2][10]

In 1894 he read the work of Philipp Lenard (1862–1947) on letting cathode rays leave the discharge tube through an aluminum window and, at first apparently without a definite aim, repeated those experiments.⁠[2]

On the evening of Friday, November 8, 1895, while working with cathode rays in his laboratory on the Pleicher Ring (now Röntgenring) in Würzburg, he came upon a previously unknown kind of ray.⁠[7][8][13]

He was studying the passage of electric current through a partly evacuated glass tube (a cathode-ray tube) when he noticed that a screen coated with barium platinocyanide, lying some distance away, glowed whenever the tube was in operation; he reasoned that cathode rays striking the glass wall of the tube produced an unknown radiation that crossed the room, struck the screen and made it fluoresce. NDB describes the observation as rather accidental: in a darkened room a fluorescent screen near his covered discharge tube lit up.⁠[10][2]

Kärin Nickelsen gives the standard account: he noticed a sheet of paper coated with a fluorescent substance glowing some distance away, and it went on glowing after he had enclosed the tube in cardboard. She points out that this account cannot be verified, because Röntgen ordered all his papers and notes to be destroyed after his death.⁠[8]

Further experiments showed that paper, wood, aluminum and other materials were transparent to the radiation and that it affected photographic plates; since it showed none of the usual properties of light such as reflection or refraction, he wrongly concluded that it was unrelated to light. Because its nature was uncertain, he called it X-radiation (X-Strahlen); it also became known as Röntgen radiation, and in German it is still called Röntgenstrahlen.⁠[10][2][12]

After the discovery he shut himself in his laboratory for weeks and spoke of it to no one, not even his wife, because he wanted to establish exactly what the rays were before going public.⁠[7]

Central to the experiments were discharge tubes with a cathode and an anode: electrons knocked out of the cathode were accelerated toward the anode and excited atoms, which emitted X-rays as they returned to lower energy states. Early X-ray tubes were partly evacuated glass vessels, often tube-shaped, hence their name.⁠[8]

X-rays pass more easily through soft tissue than through bone, so a hand placed between the rays and a photographic plate shows its bones. His wife Bertha was his first test subject: on December 22, 1895, he X-rayed her hand with her wedding ring. His first X-ray photographs also showed the interiors of metal objects.⁠[8][4][5][10]

Over Christmas 1895 he wrote his first paper, “Ueber eine neue Art von Strahlen (Vorläufige Mittheilung)” (On a New Kind of Rays: Preliminary Communication), which appeared in the Sitzungsberichte of the Physikalisch-Medicinische Gesellschaft in Würzburg; the University of Würzburg’s archives date its publication to December 28, 1895.⁠[2][6][9]

On New Year’s Day 1896 he sent the paper out; the photographs enclosed, including the X-ray of his wife’s hand, quickly prompted medical and technical applications.⁠[2]

On January 5, 1896, the Vienna newspaper Die Presse carried the first report of the discovery described in the paper, which had been written for specialists, and the news spread around the world; the Times in New York carried the discovery on January 16.⁠[4][5]

On January 12, 1896, he gave a private demonstration for Emperor Wilhelm II in Berlin.⁠[2]

On January 23, 1896, in the lecture hall of the institute building, he presented the discovery to the Physikalisch-Medicinische Gesellschaft in Würzburg; it was the only public lecture he gave on it. During the lecture he X-rayed the hand of the anatomist Albert von Kölliker, who proposed naming the rays after Röntgen, a suggestion met with enthusiastic applause.⁠[2][13][5][6]

Within weeks of the announcement in early 1896, X-rays were being used in medical imaging and in the treatment of cancer.⁠[10]

The exciting results of his systematic research were at first thought to be fairy tales, until the first X-ray photographs were published; X-ray photographs then turned up at fun fairs and in department-store attractions, though Röntgen never earned a penny from them.⁠[9]

The discovery set off a public craze: X-ray machines appeared at exhibitions and fairs and people were X-rayed casually, while the harmful biological effects were recognized only later. Pedoskope, devices that X-rayed children’s feet to check the fit of their shoes, were still in use in German shoe shops into the early 1970s.⁠[4][8]

Early radiographs exposed parts of the body for up to twenty minutes; the serious health effects of overexposure were recognized only much later, with grave consequences for test subjects and scientists.⁠[8]

In 1896 he published a second communication on the new rays, and in 1897 a third, “Weitere Beobachtungen über die Eigenschaften der X-Strahlen” (Further Observations on the Properties of X-Rays), in the proceedings of the Prussian Academy of Sciences in Berlin.⁠[2]

Horst Kant, author of the NDB article, judges that Röntgen’s slow, pedantic way of working did not suit the rapidly developing field and that he lost his international lead; after 1897 his interest in the rays waned and he returned to the physics of crystals.⁠[2]

From 1897 he was one of the curators of the Physikalisch-Technische Reichsanstalt in Berlin.⁠[2]

In the summer semester of 1900, already a celebrated physicist, he moved to Munich to take the chair of experimental physics at LMU Munich, where he remained for the rest of his life despite plans to emigrate to the United StatesUnited StatesThe United States is a federal country in North America made up of 50 states, the District of Columbia as the seat of government, and territories such as Puerto Rico and Guam; its capital is Washington, D.C. The Continental Congress adopted the Declaration of Independence on July 4, 1776. The 2020 census (April 1, 2020) counted a resident population of 331,449,281, and the 435 seats of the House of Representatives are apportioned among the states on the basis of the census.Open the full entry. It was then LMU’s only chair of physics.⁠[2][8][14][1]

The institute building, opened on November 3, 1894, had four storeys with workshops, laboratories, offices, a practical-training room, a large and a small lecture hall and a collection room, and it had its own power generation, central heating, electric lighting and connections for gas, water and electricity, which was unusual in late-nineteenth-century Munich. His office was on the second floor with a view of the inner courtyard, and his private laboratory was next door; the physics professor Joachim Rädler, who now occupies the office, recounts that Röntgen retreated to the laboratory whenever irksome visitors came.⁠[8]

In Würzburg, Wilhelm Wien, who had accepted a chair at the University of Giessen in 1899, moved after half a year to the University of Würzburg as Röntgen’s successor.⁠[15]

His students in Munich included Walter Friedrich, Abram Joffe, Paul Knipping, Peter Paul Koch, Rudolph Ladenburg and Peter Pringsheim. His main research in Munich concerned the electrical properties of crystals, crystal physics having long interested him; he also worked on thermodynamics, electrodynamics and solid-state physics and continued experiments with discharge tubes, including tubes equipped with platinum cathodes.⁠[2][8]

The Royal Swedish Academy of Sciences awarded him the 1901 Nobel Prize in Physics, the first in the field, undivided, “in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him.” He was by then a professor in Munich; his affiliation at the time of the award is given as Munich University.⁠[1][6][2]

He received the prize on December 10, 1901; a replica of the Nobel diploma is on display in the University of Würzburg’s archives. He did not give the lecture that was expected of him at the award.⁠[6][5][2]

He gave the entire prize money, 50,000 Swedish kronor, to the University of Würzburg; the Röntgen Memorial’s biography gives the purpose as supporting research, LMU Munich’s article as fostering young scientific talent.⁠[6][5][8][10]

The Deutsches Röntgen-Museum calls him Germany’s first Nobel Prize laureate and the first Nobel Prize laureate of all.⁠[16]

In 1904 he declined a possible appointment as president of the Physikalisch-Technische Reichsanstalt in Berlin.⁠[2]

Through his efforts LMU revived its chair of theoretical physics, vacant for ten years, to which Arnold Sommerfeld (1868–1951) was appointed in 1905; the post had been empty since Ludwig Boltzmann left in 1894.⁠[2][8]

LMU Munich’s article says that he inaugurated the “golden age” of physics in Munich; Sommerfeld’s lectures drew students such as Peter Debye, Peter Paul Ewald, Hans BetheHans Albrecht BetheHans Albrecht Bethe (1906–2005) was a German-born American theoretical physicist who joined Cornell University in 1935, headed the theoretical division at Los Alamos during the Second World War and received the 1967 Nobel Prize in Physics for his work on nuclear reactions and the energy production of stars.Open the full entry, Werner Heisenberg and Wolfgang PauliWolfgang PauliWolfgang Pauli (1900–1958) was a Vienna-born theoretical physicist who received the 1945 Nobel Prize in Physics for the discovery of the exclusion principle, also called the Pauli principle, and who in 1930 proposed the neutral particle later named the neutrino; he was professor of theoretical physics at ETH Zurich from 1928 until his death.Open the full entry.⁠[8]

In 1912 Max von Laue, a member of Sommerfeld’s research group, with the help of Röntgen’s doctoral students Walter Friedrich and Paul Knipping, demonstrated in Munich the interference of X-rays in crystals, confirming their wave nature and electromagnetic origin; Laue received the 1914 Nobel Prize in Physics for this. Kärin Nickelsen points out that the later decoding of the double-helix structure of DNA rested to a substantial extent on experiments with X-rays.⁠[2][8]

The same year he declined a research professorship at the Prussian Academy of Sciences in Berlin.⁠[2]

His wife Anna Bertha, born in 1839, died in 1919. After her death he abruptly broke off contact with Josephine, the daughter they had adopted together; the exhibition announced in the University of Würzburg’s 2016 press release presented this as a less kindly side of him.⁠[2][7]

He retired in 1920, and Wilhelm Wien again succeeded him, this time in the chair of physics at LMU Munich.⁠[2][10][15][14]

He spent his last years in solitude, and inflation wiped out his modest fortune. Towards the end of his life he destroyed numerous documents.⁠[2]

He died of bowel cancer in Munich on February 10, 1923, at the age of 77. Kärin Nickelsen suggests that with X-ray technology his cancer might have been detected at an early stage.⁠[1][10][8][5]

At his own request he was buried in a family grave in the Alter Friedhof (Old Cemetery) in Giessen; the city and Justus Liebig University Giessen describe this as a tribute to the town to which he felt especially close. His gravestone still stands.⁠[2][11][12]

The couple adopted Josephine Bertha Ludwig (1881–1972), the daughter of Anna Bertha’s brother; she joined the household in 1887 at the age of six.⁠[1][2][7]

Horst Kant’s NDB article calls him a particularly thorough observer.⁠[2]

The University of Würzburg’s 2016 press release describes him as an “akribischer und verschlossener” person, meticulous and reserved; the university archives’ profile also calls him reclusive.⁠[7][6]

Kärin Nickelsen describes him as quiet and retiring, a man who found his sudden fame a burden.⁠[8]

He was a keen amateur photographer and enjoyed nature, mountain climbing and hunting. The University of Würzburg’s archives hold a photograph of him at the Tschierva hut (Tschiervahütte) in Switzerland, taken on September 1, 1907.⁠[4][6]

He later called his twelve years in Würzburg the happiest of his life.⁠[17]

The Deutsches Röntgen-Museum’s homepage presents as his motto the sentence “Ich fühle mich nur wohl, wenn ich experimentieren kann” (I only feel at ease when I can experiment).⁠[3]

He applied for no patents on his discovery, holding that it should benefit all of humanity rather than be restricted to individuals through patents and licences; the University of Würzburg’s press release says that he wanted the rays to be used quickly and freely “zum Wohl der Menschheit,” for the good of humanity.⁠[2][10][17][9][7]

Horst Kant argues in NDB that his not filing any patent claims indirectly furthered rapid technical development.⁠[2]

Other inventors, such as the American Thomas EdisonThomas EdisonThomas Edison (1847–1931) was an American inventor and entrepreneur who received 1,093 U.S. patents in his lifetime. He invented or improved the phonograph, the practical incandescent lamp and its supporting electric power system, motion picture camera and viewing equipment, and the alkaline storage battery, among other things, and established industrial research laboratories at Menlo Park and West Orange, and is regarded as one of the pioneers of the modern industrial research and development model.Open the full entry, smiled condescendingly at him for this.⁠[7]

Kärin Nickelsen points out that, his father having been a cloth merchant, he was already set up for life by his inheritance and did not need income from patents, which favoured the rapid application and spread of the discovery; she adds that this does not mean he lived austerely.⁠[8]

His research topics also included elasticity, capillary action in fluids, the specific heats of gases and piezoelectricity.⁠[10]

His early research centred on gases and liquids, in connection with heat and pressure.⁠[9]

NDB counts 60 papers in all; the Röntgen Memorial’s biography speaks of nearly 70 published works.⁠[2][5]

In 1888 he published his paper on the electrodynamic force produced by the motion of a dielectric in a homogeneous electric field (Über die durch Bewegung eines im homogenen elektrischen Felde befindlichen Dielektricums hervorgerufene elektrodynamische Kraft) in the proceedings of the Berlin Academy.⁠[2]

In 1898 his three communications on the new rays were reprinted together under the title “Ueber eine neue Art von Strahlen” in the Annalen der Physik und Chemie, new series, volume 64, pages 1–37.⁠[2]

In 1935 L. Zehnder edited his letters as Briefe an L. Zehnder, and in 1972 F. Krafft edited Über eine neue Art von Strahlen, an unaltered reprint of the edition published by the Physikalisch-Medicinische Gesellschaft in Würzburg for his seventieth birthday, with a biographical essay by W. Gerlach.⁠[2]

In 1995 a facsimile of the Würzburg 1896 edition of Eine neue Art von Strahlen was published in Braunschweig.⁠[6]

In 1896 he received the Prix Lacaze of the French Academy of Sciences and the Rumford Medal of the Royal Society, an honorary doctorate in medicine from the University of Würzburg and the honorary citizenship of Lennep, and he became a corresponding member of the Prussian Academy of Sciences and of the Bavarian Academy of Sciences and Humanities.⁠[2][10]

The same year he received the Order of Merit of the Bavarian Crown (Verdienstorden der Bayerischen Krone) but declined the ennoblement that came with it.⁠[2][10][6]

He became a full member of the Bavarian Academy of Sciences and Humanities in 1900, received the title “Exzellenz” in 1908 and the Pour le Mérite for Sciences and Arts in 1911.⁠[2]

He also received honorary doctorates from the Technische Hochschule München (1918) and from Frankfurt am Main (1920), and in 1921 he became an honorary citizen of Würzburg; he received numerous other orders and distinctions besides.⁠[2][6]

At the end of 1895, as Philipp Lenard was about to resume his work on cathode rays in Aachen, Röntgen’s discovery took him by surprise; he was disappointed not to have made it himself, since his own experiments should have led him straight to it.⁠[18]

His disappointment was also directed at Röntgen, whom he had helped to obtain suitable discharge tubes and who never mentioned that help; for the rest of his life Lenard used the term Hochfrequenzbestrahlung instead of Röntgenstrahlen.⁠[18]

The Deutsches Röntgen-Museum was founded in 1930 in his birthplace, Remscheid-Lennep, where material on him is collected, and has existed for more than three quarters of a century; it describes itself as the only institution in the world that fully documents his life, achievements and influence and the many applications of X-rays. Renovation and expansion of the museum began in 2004. It has about 2,100 square meters of exhibition space and more than 155,000 objects, about a quarter of them on display and the rest stored at Radevormwald-Dahlerau.⁠[16][2][4]

His birth house, about 250 years old, was bought by the German Röntgen Society (Deutsche Röntgengesellschaft) in 2011; modernized with the society’s support, it has been open to visitors since spring 2020 and shows original documents and objects relating to his life and discovery. It lies just under 200 meters from the museum and is now part of it.⁠[4][3]

Every year the city of Remscheid awards the Röntgenplakette (Röntgen Plaque) to eminent scientists and Nobel laureates; the museum’s homepage celebrates the plaque’s 75th anniversary. The homepage also states that selected images have officially become part of the UNESCO Memory of the World register.⁠[3]

In Würzburg the Röntgen-Gedächtnisstätte occupies the former Institute of Physics where he discovered X-rays, a building that now belongs to the Technical University of Applied Sciences Würzburg-Schweinfurt (THWS); open to the public since 1985, it was extensively renovated in 2020 for the 125th anniversary of the discovery. It shows the restored Discovery Laboratory with the original apparatus on the spot of the discovery, and its entrance hall displays his documents, personal belongings and a handwritten description of the experimental set-up. The original lecture hall of his public lecture of January 23, 1896, could not be preserved; a lecture hall with historic seating in a similar location is still used by THWS.⁠[13]

The Röntgenring and the Röntgen-Gymnasium in Würzburg and the Röntgen Institute in Düsseldorf are named after him. In 2020 the University of Würzburg, the city and partner organizations marked the 125th anniversary of the discovery and the 175th anniversary of his birth, with an exhibition at the New University (Sanderring 2) from October 15, 2020, to March 31, 2021.⁠[6][19]

For the 120th anniversary of the discovery, the University of Würzburg’s archives under the university archivist Marcus Holtz produced, together with the University Library, the exhibition “120 Jahre Röntgenstrahlen,” nine posters that also set out to make his personality more visible; after the town hall and the Institute of Physics, it was shown in the customer hall of Sparkasse Mainfranken on Hofstrasse until February 4, 2016.⁠[7]

Since 1960 Justus Liebig University Giessen has awarded the Röntgen Prize in his honour every year; it is the university’s most highly endowed research prize and is intended mainly for young scientists with outstanding work in basic research in radiation physics, photonics or radiation biology.⁠[11][12]

Giessen also has a Röntgen monument in the form of X-rays by the Berlin artist Erich Fritz Reuter (1962) in the Südanlage, in the Theaterpark next to the Stadttheater; a street named after him; a plaque on his former home at Südanlage 17; a 1932 bust by Ernst Kunst (1896–1959) on the ground floor of the main university building, the former home of the Institute of Physics, beside a reproduction of his Nobel diploma; and a street-art mural with Röntgen motifs by the Giessen collective 3Steps on a transformer station between the main building and the Theaterlabor; guided city tours regularly follow in his footsteps.⁠[11]

On February 10, 2023, the centenary of his death, Giessen’s mayor Frank-Tilo Becher and Martin Kramer, vice-president for research and early-career support of Justus Liebig University Giessen, laid a wreath at his grave.⁠[11]

After his death LMU Munich commissioned several busts of him; only one survives, recently installed on the second floor of the physics building in front of his former office.⁠[8]

In 1923 E. Esseö made a bronze portrait medal of him.⁠[2]

Chemical element 111 is named roentgenium (symbol Rg) in his honour. It was first produced from nickel and bismuth by Hofmann et al. at GSI in Darmstadt; the first experimental proof recognized by IUPAC dates from December 8, 1994, while IUPAC’s announcement says that the element was synthesized exactly 100 years after his discovery. A joint IUPAC–IUPAP working party confirmed the discovery in 2003, and following the 80th meeting of its Bureau in Bled, Slovenia, IUPAC officially approved the name as of November 1, 2004.⁠[20][21]

BritannicaEncyclopædia BritannicaEncyclopædia Britannica is a general English-language encyclopedia first published in Edinburgh, Scotland, in 1768; the name also refers to its publisher, Chicago-based Encyclopædia Britannica, Inc. (which presents itself as The Britannica Group). The print edition ended in 2012, and the company’s main businesses since then have been the online encyclopedia Britannica.com, digital education products for schools and libraries, and Merriam-Webster dictionaries.Open the full entry writes that his discovery heralded the age of modern physics and revolutionized diagnostic medicine.⁠[10]

The Deutsches Röntgen-Museum describes him as a modern, creative and interdisciplinary thinker of around 1900 whose discoveries set new benchmarks for excellence in science and research and helped establish the “Made in Germany” label in engineering, technology, science and research, and who set high standards for the honour of the Nobel Prize; the museum also credits his work with transforming medical diagnostics and therapy and paving the way for high-tech applications.⁠[16][3]

The Röntgen-Gedächtnisstätte calls him one of the most significant scientists to have taught and researched at the University of Würzburg and the discovery of X-rays one of the most significant discoveries in the history of science; the University of Würzburg’s archives call him one of the university’s most important scholars; the university’s 2016 press release calls him a “genialen Physiker,” a brilliant physicist.⁠[17][5][6][7]

A 2014 article in the Pharmazeutische Zeitung calls him one of the first media stars of science and his discovery a turning point in the history of science; in the article Uwe Busch, deputy director of the Deutsches Röntgen-Museum, stresses that Röntgen’s work was ordinary physics done with equipment found in any physics laboratory, and that many researchers had prepared the way, but Röntgen was the first to recognize and investigate the phenomenon.⁠[4]

Kärin Nickelsen points out that X-rays make the invisible visible without destroying the structure they reveal, either directly, as with bones, or through diffraction, as in crystallography; today they are used in medicine, materials testing, X-ray microscopes and space telescopes.⁠[8]

In 2023 Giessen’s mayor Frank-Tilo Becher said that Röntgen had found fertile ground in Giessen and at its university, where research could serve all of humanity, and that the city is proud to count him among its sons.⁠[11]

Deutsches Röntgen-Museum: Official website: https://roentgenmuseum.de/ (opens in a new window).⁠[3]

Röntgen-Gedächtnisstätte Würzburg: Official website: https://wilhelmconradroentgen.de/en/ (opens in a new window).⁠[17]

Utrecht University: Official website: https://www.uu.nl/en (opens in a new window).⁠[22]

University of Giessen: Official website: https://www.uni-giessen.de/ (opens in a new window).⁠[23]

University of Würzburg: Official website: https://www.uni-wuerzburg.de/ (opens in a new window).⁠[24]

LMU Munich: Official website: https://www.lmu.de/en/ (opens in a new window).⁠[25]