As humans beings, we always have been curious about the mystery in the things that surround us, especially the daily events that can’t be explained that easily. Step by step as we expand our knowledge we learn that everything has a reason to be. It had happened that someone observes how something in the air is eventually attracted by the ground and realize that there is something that occurs every time, but what causes it? Or the situation in which a car is moving at a constant speed and stops when the driver wants to, but when we think about it in detail we realize the answer is more complex than just pressing the brakes. As those two examples, the world is full of common situations that have unusual explanations, wish makes the life of the curious exiting and more interesting. The majority of the people are conscious that the situations we study start to become an object of interest thanks to the observation of any particular aspect of something that caught the attention of our senses. Now, let’s focus on one of the senses, sight. Immediately after we open our eyes we are constantly receiving information from our surrounding, but what are the steps that are needed to be following in order to perceive the visual characteristics of an object as it is? What allows us to see the colors? What creates the colors or the rainbow itself? What allows us to see our reflection in a mirror or why the situation changes when it’s dark? All of those questions are part of our need to learn and they are all connected with one thing, the light.
But, what is the light? Using science of Physics as our tool we will try to solve many of our established unknowns. Properly speaking, the light is the radiation that spreads in form of waves in the empty space called electromagnetic wave. The color is related to the frequencies of the light in the spectrum called the visible spectrum with its wave lengths between 400nm to 750nm. More than 750nm and less than 400nm won’t be perceived by the human eye. Still, what is the light? In the beginning was well known that the light was pure and that the combination of the light with objects gives the colors, until scientific developed the prism. Through this tool scientists understood they were wrong about the white light. What we obtain from there, the white light is actually the combination of all the colors. Using the prism we can actually see the decomposition of the light in red, orange, yellow, green, blue, and violet. Another common example where it happens in nature is the rainbow. One drop of the rain works as well as a prism, spreading white light into the full spectrum. Each drop allows us to see just one color in the spectrum in our range of visibility. It is the combination of many drops reflecting one specific wave length which allows seeing the rainbow with all the colors in the spectrum.
We now know what the light is, but how is it possible that we can see a particular color from an object? To answer this question we will return to the fact that the white light is formed by mixing all the colors. What occurs when the white light hits any surface is that when the light gets in contact with the surface all the colors are absorbed except the color that represents the color of the object itself. The colors that are not absorbed bounce away from the object. This action is what our eyes capture at the moment of seeing a color. We end up seen the color that wasn’t absorbed by the object. The colors that are absorbed have an energy that it’s never destroyed is transformed into other expression of energy such as heat. Another thing that creates curiosity is the fact that the light experiences changes in its direction each time it gets in contact with any surface. If the surface is smooth the incoming light ray will bounce resulting in a reflected ray, which has the same angle to the surface as the incoming ray, like it occurs when using a mirror. On the other hand, if the light ray gets in contact with a rough surface, the ray will reflect in many different directions which will cause the reflection to get diffuse as it occurs using a paper.
In conclusion, science, in our case Physics, can explain common events that have unusual explanations letting ourselves be guided by fundamental concepts. One of our most reliable senses, the sight depends not only in the capacity of our eyes; it depends in many physical aspects related with the light, what forms it and how it moves, things that we don’t usually think that happened. We use to think that the light is everywhere until it’s dark or that we instantly see it when we open our eye, but we don’t realize that just because the events are not easily captured by our senses, it does not mean they do not exist.
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