For his work on canal ray sources in the 1920s, German physicist Emil Rupp was regarded as one of the most important figures in his field. His research captured the interest of Albert Einstein, resulting in a collaboration that probed the wave and particle natures of light. Despite flaws and inaccuracies in his work, Rupp's controversial investigations continued for another ten years — until it was discovered he'd forged everything he had ever published. In a profile of the scientist, io9 explains how Rupp was able to deceive Einstein and divide the German physics community, revealing how one bold claim too many led to his downfall.