An initially impractical scientific advance that was later found to have practical applications is the photoelectric effect. In the late 19th century, it was discovered that matter could form and liberate electrically charged particles when it is irradiated by electromagnetic radiation. Telegraph operator Joseph May observed that when exposed to sunlight, selenium bars vary in resistance. From this discovery, the conclusion can be drawn that variations in light intensity can be transformed into electrical signalsthe foundation of television transmission.In 1873, the knowledge that changing light intensity could be translated into electronic signals was virtually useless. Americas Reconstruction society was much less science-oriented, and lacked the resources to take advantage of the new knowledge. European researchers in the field of image projection were exploring other (dead end) techniques. It was not until 1935 that television broadcast started, in major European cities. The following year, an all-electronic television was adopted in England. It used a photoelectric mosaic to convert electrical signals into a viewable image. The example of the photoelectric effect leading to the development of modern television shows that all scientific discoveries are valuable. Their value is not always based on their immediate applications, but on their potential to be applied to revolutionary ideas in the future....
