> For which discovery did German physicist Wilhelm Conrad Röntgen win the firstever Nobel Prize in Physics in 1901?> And the answer: X-rays. Photo credit: public domain.In 1895, Röntgen was testing if cathode rays couldpass through glass when he noticed fluorescence coming from a nearby chemicallycoated screen. He called the rays that caused the glow X-rays because of theirunknown nature.The history of medical technology has been continually shaped by groundbreakinginnovations. In 1896, Röntgen took 15 minutes to capture the world-famous firstX-ray shot of his wife's hand. By 1909, the time it took to capture an X-ray wasdown to just milliseconds— making the contours of the heart visible for the veryfirst time. In Röntgen's initial X-ray, several things were happening at once. When high-energy electrons in a cathode tube hit a metal component, they either got sloweddown and released extra energy, or kicked off electrons from the atoms they hit.A consequential reshuffling, again, released energy. In both cases, the energywas emitted in a form of X-rays, which is a type of electromagnetic radiationwith higher energy than visible light and lower energy than gamma rays. X-raysare powerful enough to get through many kinds of matter, and portray them assemi-transparent. Soft tissue in internal organs contains few electrons, and isless visible in an X-ray machine.When X-rays interact with matter, they collide with electrons. Substances thatare more dense (like bones, for example), have a higher number of electrons andtherefore can be better observed through X-ray radiation. Soft tissue, on theother hand, is found in internal organs and contains few electrons. Thus, it isless visible in an X-ray machine.X-rays are especially useful in medicine as they are able to create distinctpictures of organs, like bones, without harming them. Despite its relativesafety, those who undergo an X-ray wear lead aprons to prevent any side effectsas a result of exposure to radiation. Learn more about the history of X-rays and their application in the medicalfield here[https://www.nde-ed.org/NDETechniques/Radiography/Introduction/history.xhtml#:~:text=X%2Drays%20were%20discovered%20in,a%20table%20near%20his%20tube.].