More Light on Information [Historical

Abstract

At the turn of the 20th century, when electric light superseded chemically fueled lamps [1], new uses of light began to emerge. They regarded information processing and transmission rather than power and within a few decades resulted in the technological domain of photonics. These applications consisted of photocells, light-emitting diodes (LEDs), lasers, fiber optics, and holography. In that same span of years, progressing from the achievements of Maxell and Hertz [2], science advanced into new theories on light. After Max Planck?s (1858?1947) breakthrough of energy quanta of 1900, Albert Einstein (1879?1955) lived his annus mirabilis in 1905, when he published four papers in Annalen der Physik, each a milestone in theoretical physics. The first one, ??ber einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt? (?On a Heuristic Viewpoint Concerning the Production and Transformation of Light? [3]) justified Planck?s result by means of the photoelectric effect, which deems light to consist of discrete quantized packets of energy. The theory was so innovative that it was accepted only after Robert Millikan?s (1868?1953) experimental confirmation in 1914. Ultimately both Einstein and Millikan won the Nobel Prize in physics, in 1921 and 1923, respectively, for these achievements. Still, Heinich Hertz had already observed the photoelectric effect in 1887, but he did not continue researching the subject and moved on to electromagnetic waves. The name ?photon? for the light quantum was accepted after the American physicist Arthur Compton (1892?1962, the 1927 Nobel Laureate in physics) used it in 1928. A major step ahead in the theoretical physics of light came in 1948, when Sin-Itiro Tomonaga (1906?1979), Julian S. Schwinger (1918?1994), and Richard P. Feynman (1918?1988) presented their independent but consistent models of quantum electrodynamics, aimed at describing the electromagnetic interactions between electrons and photons (i.e., between matter and light) in quantum form. For these works, they shared the 1965 Nobel Prize in physics [4].