LIGHT: A FUNDAMENTAL FORCE IN OUR WORLD
If asked what light is, one could say that it's one of the most basic
elements of our world and our universe as we perceive it. It is through
sight that we receive 90% of our information. It is through the use of
telescopes aiding the naked eye that we are aware of the heavenly bodies
around us. It is through light that the energy from the sun is transferred
to us. The sun's energy supports the food chain; plants use it to turn
water and CO2 into energy usable by other organisms. Solar energy was also
used, 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 basic
understanding 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 both
particles and waves. It follows the same rules as a wave does--it moves in
a regular fashion, in a perfect sine wave at a certain frequency. It
travels in a straight line, and is subject to refraction. All of these
characteristics are found in waves of any type, from radio frequency waves,
up to Gamma and X- rays. Light, however, also exhibits qualities
characteristic of particles such as neutrons and protons. A photon, or
quanta, is the "packet" of energy that is sent in a light wave. Like a
particle, the photon is believed to have a finite mass, and has the ability
to affect other matter. As light strikes a photovoltaic solar cell, it
knocks electrons in the silicon atoms on the surface into a higher state of
energy. When these return to their normal, or "ground" state, energy is
produced in the form of electricity. Thus, light is termed a
"wave-particle," and this property is called the "wave-particle duality of
nature." Many questions concerning what makes up light still lie
unanswered, 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 a
fire, it produces light and heat. (Heat, which is infrared radiation, is
another type of light energy.) The light and heat are a result of a
chemical reaction, the combining of oxygen with the carbon in the wood.
This reaction leaves behind products which have less potential energy than
they started with. The energy, which left as light and heat, was produced
when electrons dropped in energy levels during the reaction. The excess