The Naked Truth or the Shadow of Doubt? X-Rays and the Problematic of Transparency

Late into the evening of 8 November 1895 Wilhelm Conrad Röntgen, a physics professor at the University of Würzburg, made a discovery that would revolutionize science almost overnight. While conducting experiments with cathode rays in his laboratory, he remarked a peculiar glow with highly unusual properties emanating from a nearby fluorescent screen, the source of which he could not identify. The rays were not refractable like visible light, nor could they be magnetically deflected as cathode rays could. Most remarkable, however, was their capacity to penetrate a variety of opaque substances: wood, paper, rubber, and most astonishingly, human flesh. The rays not only passed through these materials, but they made marks on photographic plates placed behind them, leaving a shadowy picture of the interior of the original object. Unable to pinpoint the rays’ physical makeup, Röntgen called them X-rays.1 News of Röntgen’s discovery spread quickly across Europe and the United States. The theme that resounded throughout these reports was the X-rays’ capacity to make visible what was imperceptible to the naked eye. A 16 January 1896 headline in The New York Times was typical, claiming in bold type: “Hidden Solids Revealed!” The papers trumpeted the X-rays’ ability to see through opaque objects of all kinds, and illustrated these reports with pictures demonstrating the X-rays’ uncanny powers of revelation [Fig. 1, Fig. 2, & Fig. 3].