We see things every day; from the moment we open our eyes in the morning to the second we close them to sleep at night we are seeing things. Every day you wake up, you open your eyes and you see. You see using light. Light enables you to see the shoe that was left haphazardly on the floor before you trip on it. Light keeps you from banging your toes on the corners of furniture in the dark. Light allows you to see. Not just to see but to see in color. Colors do not really exist, they are simply a reflection of a certain wave of light to your eyes. All you ever really see…is light. Some things reflect it, some absorb parts of it, some scatter it, and some allow it to pass right through, but all you see is light.
Light is one of the most fascinating and taken for granted aspects of life. But there is more to light than you think. Light is not simply a bulb that you put up so that you can see in the dark. Light is one of the more complicated and confusing things to explain. While we can mold it, control it, manipulate it, and even create it but we cannot completely understand it. Basically light is energy. It moves as both a wave and a particle. Light is the only thing that does this. Light can also move through anything. It does not require a medium to move like other waves of energy do. Light can move through a vacuum. In other words the voids of space cannot keep light from us.
Light is essential to see. Without light, you see nothing, but also without light…there is nothing to see. Without light there would be no food to eat and no air to breath. In other words…without light there would be no life. In a very broad sense life could not exist on earth without the readily available presence of light. I imagine that at least some of you are familiar with the process of photosynthesis where a plant uses chlorophyll to absorb light from the sun and in turn creates sugars which are broken down into glucose which provides nutrients or energy for the plant. What you may not know is what goes into this process. Plants contain a compound called adenosine diphosphate or ADP. ADP is essentially useless…it does nothing. When light is absorbed it initiates a series of chemical reactions that change ADP into ATP adenosine triphosphate, which is really cool. The plant is basically dead…it has no life…it can do nothing. But when light is absorbed by the plant…the plant comes to life. What is produced: ATP is food for the plant…we would call it a nutrient. This nutrient feeds not just the plant, but any animal that eats the plant. Do you see the effect of light? Light brings that which was dead to life…when light is absorbed…the organism that absorbed it has life.
You see it is not food that enables your body to function and have life, it is the nutrients that are found in that food. All of those nutrients work their way back to plants as a result of their absorption of light.
Life can be broken down into what are called trophic levels. You might think of this as the circle of life. In the first trophic level plants absorb energy from the sun and create nutrients. In the second level an animal eats that plant and gets the nutrients, one such animal would be a squirrel. In the third trophic level an animal eats an animal that ate the plant and in turn gets the nutrients, here you have a hyena. Finally in the forth tropic level you have an animal that eats the animal that ate the animal that ate the plant. A lion would fall into this grouping. All trophic levels of life depend on the energy that comes from the plant that was created by light. Without the plants production of nutrients the plant would die. Without being able to eat the plant that produced nutrients that animal would die. Essentially without light being absorbed by a plant…there would be no life. Light is necessary for life.
There is another important aspect to this process: the air we breathe. During the process of photosynthesis plants emit oxygen…which we need to breath. They only emit this oxygen when they are absorbing energy from light. No light…no oxygen…no oxygen…no life. Light is the source of all life…and it is far more complicated than you might think.
In addition to affecting the biological world light also affects our own physiological existence in two ways. Which is just a fun way of saying: it affects us. The First: UV radiation (light from the sun) produces or changes a compound in our blood into Vitamin D. Vitamin D promotes bone formation and allows the body to absorb calcium which gives strength and density to your bones. Without vitamin D your bones would be frail and easily broken. The only natural way in which Vitamin D is produced is through light. The second: Light is a melatonin inhibitor. Melatonin is a chemical secreted by your retina, G.I track, and pineal gland. Melatonin is what enables REM sleep. It makes you tired and helps you fall asleep and increases the vividness and frequency of dreams. When you come home from a long days work…it is not the days work that makes your body want to sleep…it is your bodies reaction to the change in lighting. Have you ever woken up in the morning but decided to go back to sleep, then when you did get up you were tired all day? What happens is you body absorbs light and melatonin is inhibited. But then when you go back to sleep your body receives a second dose of melatonin and it drains your energy more than if you had just gotten up.
When light fades melatonin is released and you are better able to fall asleep. Melatonin is important and can be very helpful. It is also very bad if you get too much of it. Too much melatonin will cause serious lack of energy and depression. This calming, tranquil feeling that melatonin uses to help you sleep will lower your energy and spirits if you have too much. So without light…there would be no joy…and no energy. Without energy we would all just decay away. Without light there is no life.