If asked what light is, one could say that it’s one of the most basicelements of our world and our universe as we perceive it. It is throughsight that we receive 90% of our information. It is through the use oftelescopes aiding the naked eye that we are aware of the heavenly bodiesaround us. It is through light that the energy from the sun is transferredto us.
The sun’s energy supports the food chain; plants use it to turnwater and CO2 into energy usable by other organisms. Solar energy was alsoused, indirectly, to produce all of the fossil fuels that we consume daily. Since light is such a basic part of our existence, we should have a basicunderstanding of what it is. What we call light, the intangible, powerful force that powers our world,is somewhat hard to define in real terms. It shares properties with bothparticles and waves. It follows the same rules as a wave does–it moves ina regular fashion, in a perfect sine wave at a certain frequency.
Ittravels in a straight line, and is subject to refraction. All of thesecharacteristics are found in waves of any type, from radio frequency waves,up to Gamma and X- rays. Light, however, also exhibits qualitiescharacteristic of particles such as neutrons and protons. A photon, orquanta, is the “packet” of energy that is sent in a light wave. Like aparticle, the photon is believed to have a finite mass, and has the abilityto affect other matter.
As light strikes a photovoltaic solar cell, itknocks electrons in the silicon atoms on the surface into a higher state ofenergy. When these return to their normal, or “ground” state, energy isproduced in the form of electricity. Thus, light is termed a”wave-particle,” and this property is called the “wave-particle duality ofnature. ” Many questions concerning what makes up light still lieunanswered, but this much is thought to be true. Light can be produced in a variety of ways. Our sun, like other stars,uses nuclear fusion to produce energy in the form of light and radiation.
We can produce light artificially using several methods. If one starts afire, it produces light and heat. (Heat, which is infrared radiation, isanother type of light energy. ) The light and heat are a result of achemical reaction, the combining of oxygen with the carbon in the wood.
This reaction leaves behind products which have less potential energy thanthey started with. The energy, which left as light and heat, was producedwhen electrons dropped in energy levels during the reaction. The excessenergy from one atom was given off as a photon, producing light. If oneexamines a fluorescent or incandescent light bulb, one can see that all itis doing is having electricity stimulate a metallic or gaseous substrate,causing it to give off photons.
The principle is the same as it was withthe fire, only it is more controlled. Still more controlled is the laser,which puts out its photons in a single frequency. This is achieved througha carefully designed apparatus which stimulates materials in a way thatallows them to only put out light at a certain wavelength. Laser light is,therefore, of all one color. White light, or sunlight, is a broad mixtureof wavelengths.
All methods of producing light, natural and artificial,share one common feature: they rely on electrons changing energy levels toproduce the photons. As there are a variety of methods of producing light, so are there amultitude of ways it can be applied. The most obvious use of light is insupporting our food chain. Without light energy, nothing could live on ourplanet. The plants, which are at the bottom of the food chain, supplyenergy to all other organisms. We as humans are adapted to having sunlightaround us, and taking in information with our eyes.
Aside from keeping usalive, light is also employed in highly specialized applications. Laserlight is being used in surgery. The highly concentrated beam of light isfar more precise than any surgeon’s hand, and much finer than the sharpestblade. In the area of communications, light is used in fiber optic networksfor fast, crystal-clear connections. (Fiber optics allow light to travel ina finely directed path with very little distortion. ) Optical components incomputers are starting to see use.
Also, lasers are being used to produceholographic images, both for industrial and commercial markets. Holographicpictures can show an object three dimensionally, and in great detail. Finally, new ways of utilizing the sun’s energy are being developed thatwill allow light to be more efficiently converted to electricity. Thus,light indeed has a wealth of applications. It must be remembered that, like most other things around us, light issomething utilized on a daily basis, yet little understood. With continuedresearch, we may someday unravel the mysteries surrounding this uniqueforce which is constantly at work in our universe.
The applications oflight in the present are nothing compared with what could be gained if wecould understand this strange mechanism; it may someday be the key tosolving our energy problems, or unlocking the secret of the universe.
