Stephen Simmons
M. Branchetti
11/27/12
Final Research
Shed Some Light
Light has been a constant area of study since Empedocles initially postulated the first theory of light before 435 BCE. While early theories like his were based on rudimentary understandings of science, and were inadvertently proven false, they were crucial stepping stones for later generations to build off of. Research into the modern understanding of light and its functionality, as is accepted today, originated with Robert Hooke?s Wave Theory in 1660. The scientific discoveries between then and now, as a result of studies in this field alone, have changed how humans perceive everything, and have shown that there is so much more to learn. Light, there is more than meets the eye.
?Up to the Twentieth Century, reality was everything humans could touch, smell, see, and hear. Since the initial publication of the chart of the electromagnetic spectrum, humans have learned that what they can touch, smell, see, and hear is less than one-millionth of reality. Ninety-nine percent of all that is going to affect our tomorrows is being developed by humans using instruments and working in ranges of reality that are non-humanly sensible? (Fuller 130). The charting of the electromagnetic spectrum began in 1800 with William Herschel?s discovery of infrared light. This was followed shortly thereafter by Johann Ritter identifying what would later come to be known as ultraviolet light, in 1801. Using silver halides, the same chemicals used for photographic film, he noticed that some colors were more effective at darkening the salt crystals. From that, he hypothesized that there was an invisible form of light beyond the violet spectrum, which he had initially named ?deoxidizing rays? (Ball).
James Clerk Maxwell proposed a series of four equations in 1864 based off of his own research and the research of other scientists such as Faraday, Ampere, Volta and Ohm. The series known as ?Maxwell?s equations? demonstrated that electricity, magnetism and light are all in fact waves of electromagnetism. This theory played a pivotal role in linking electricity, magnetism and light and led to him discovering the electromagnetic nature of light and producing a unified model of electromagnetism; which is now referred to as the ?second great unification in physics? (Nahin, Ball). Radio waves were initially theorized by Maxwell, and remained theoretical until 1887, when Heinreich Hertz successfully demonstrated their existence in in a lab by building a spark gap radio transmitter. Maxwell also predicted the existence of microwaves from his equations, and they were actually produced during Hertz?s experiment in 1887, but first documented use of the term ?micro-wave? was not until 1931 (Ball, Kahn and Pi 15). Percy Spencer is the man generally credited with officially discovering them in 1945 using a magnetron (Clark).
X-rays were first studied in depth by Wilhelm Rotengen in 1895. Using a cathode ray tube, he noticed that his detector, which was a fluorescent screen of barium platino-cyanide, would glow when a discharge was passed through the tube, even though the tube was covered. Convinced that he had found a new type of radiation, he named them ?X-rays? after the algebraic variable. The final region of the EM spectrum goes to gamma rays. These were first disinterred by Paul Villard in 1900 while he was studying the radiation emitted from radium during its gamma decay (Ball).
The electromagnetic spectrum is the charted range of all possible frequencies of electromagnetic radiation. Its uses are predominantly in science for spectroscopic and other probing endeavors as a way to study and characterize matter. It is composed primarily of seven different types of waves: radio waves, microwaves, infrared waves, visible light, ultraviolet light, x-rays and gamma rays. They are listed on the chart in the order of longest wavelength, lowest frequency, kelvin intensity and quantum/photonic energy on the left to the shortest wavelength, highest frequency, kelvin intensity and quantum/photonic energy on the right. The waves/rays range in size from gamma rays as short as 10-12 meters, comparable to atomic nuclei, to radio waves as long as, or theoretically even longer than, 1 kilometer (insert citation).
Each of the seven regions has its own set of characteristics and uses. Radio waves have the lowest frequency bands, ranging from as low as 3 Hz to the highest 300 GHz and are separated into eleven sub-categories called ?bands? within their region by factors of ten according to their frequencies. There is not a wide range of uses for